hello welcome to the JINA-CEE
livestream event today we're going to be
discussing the impact of LIGO/VIRGO
neutron star merger discovery on
research and nuclear science I'm Luke
Roberts at Michigan State University and
I'm going to be moderating today so our
aim is to foster discussion about new
research directions and nuclear physics
and astrophysics that have been opened
up by the multi messaging your signals
from this merger and hopefully more
mergers to come that we detecting
gravitational waves so we're going to
have a number of short talks about the
observations themselves and the
interpretations of these observations as
well as what the capabilities
experimental nuclear physics
capabilities are for measuring some of
the properties about nuclei we might
want to know for these events and then
we're going to have a panel discussion
about next steps and questions about
this event including the speakers as
well as some other panelists the panel
will address questions from the audience
so if you have questions either during
the talks or during panel discussion you
can either tweet them to us using
hashtag GW nuclear so you can see that
behind me or you can find that online or
if you don't use twitter feel free to
send them by email to gwnuclear@nscl.msu.edu
and so rather than answering
questions after each talk we'll sort of
agregate all the questions and save them
for the panel discussion so if you have
questions during talks please just tweet
them to us so today we're gonna have
five speakers we're gonna hear from
Duncan Brown at Syracuse University
who's a gravitational wave astronomer
we're gonna hear from Nancy castle wall
at the California Institute of
Technology who's a time domain
astronomer to tell us about the
electromagnetic signals that were
observed in coincidence with GW 1708 17
dan Kayson is also going to tell us
about interpreting these electromagnetic
signals so he's the theorist at UC
Berkeley Jocelyn Reed at Cal State
Fullerton is going to talk to us about
interpreting what the gravitational wave
signals mean for neutron star radio and
neutron star properties and then we're
gonna hear from Artemus crew at Michigan
State University was nuclear
experimentalist
going to tell us about next current and
next generation nuclear facilities that
can help us make measurements that can
inform these observations we're also
going to have panelists on ER hey Mian
who's at Notre Dame who's a nuclear
experimentalist ondrea's Bao swine who's
at the Heidelberg Institute for
Theoretical studies and who's a theorist
who works on modeling neutron star
mergers we're gonna have Jim Latimer a
theorist at Stony Brook University and
we'll also have Brian Metzger a theorist
at Columbia University on the panel so
our first talk today will be from Duncan
Brown about just what the gravitational
wave detection is from GW170817 are so
thanks Duncan for joining us and if you
have any questions while Duncan's talk
is going on feel free to tweet them and
we'll collect those for the end
so go ahead Duncan welcome okay thank
you Luke let me share my screen so you
should be able to see my talk okay can
you see that yep right okay so thanks
for inviting me and I'm going to give an
introduction to GW 79 17 the the neutron
star merger that was observed in
gravitational waves and across the
electromagnetic spectrum I'm just going
to talk about the gravitational wave
detection and also the briefly mentioned
the gamma-ray burst detections they
happened
within a couple of seconds of each other
and then I'll leave it a Mountie to talk
about everything else electromagnetic so
when we start with this slide which is a
diagram of advanced LIGO the laser
interferometer gravitational-wave
Observatory this is a Jewelry cycled
fabry-perot detector it's the the second
generation ground-based gravitational
wave detector I won't go into too much
detail on the way the detector works all
I'm going to say is that this is the
schematic design of the detector if you
build a detector that performs exactly
to the design that we are hoping to
see that the noise come on the right so
the graph on the right shows
gravitational wave frequency on the
x-axis and the the amplitude spectral
density of the noise and the detector on
the y-axis and this is the B predicted
total noise and the detector advanced
LIGO is basically a quantum noise
limited detector across much of the band
with the little bit taken out from the
the mirror coating noise in the middle
this is the expected sensitivity of
advanced LIGO once we watch for each
design let me say that you know that
this sensitivity we're seeing by neutron
stars to an average distance of over two
hundred megaparsecs the universe seems
to really likes gravitational
astronomers because LIGO is not yet at
this sensitivity we've already seen too
many binary black holes for me to
remember the exact number of stuff my
head is what's public and what's not and
and one by me shall star detection and
and the two things to say is that our
first binary black hole detection was
unambiguously loud and our first binary
neutron star detection which is shown on
this slide was also absolutely screaming
loud it was actually louder in network
SNR and the detectives for the binary
neutron star detection than the the GW
1509 14 Barney black hole detection was
so this is the loudest gravitational
wave signal that we've seen today this
slide shows the gravitational wave
signal seen in the in the 3 detectors so
the x-axis on this slide is time in
seconds and unlike our binary black
holes that show a fraction of a second
of merger signature you can see starting
28 seconds before the the end time of
the signal stretching all the way and I
claimed if you if you squint you look
closely in Livingstone you can see a
trace of a signal in in the in the data
this shows a time frequency spectrogram
of each of the detected data outputs so
the the y axis here is gravitationally
frequency and the color shows the the
normalized amplitude of the time
frequency decomposition of the detection
and you can see the binary neutron star
signal sweep all the way through the band of Livingston you can start to see it sweep
from around 40 Hertz or so by I in in
hanford up to a merger frequency where
it starts to disappearing the noise
around 500 Hertz now remember this is a
visual representation we actually do
both the detection and parameter
measurement using mass filtering using a
match filter likelihood and the matched
filter can see the signal that effect
the data for over a hundred seconds in the in
the defective data so this is the you
know it's so loud you can see by eye and
the detected data but the filtering in
the parameter measurement can see it for
longer than even you can see by eye
these tartaric inspector grounds
Livingstone was on most sensitive
detector Hanford was with less sensitive
and Virgo was was the least host of or
three detectors you can't actually see
the Signum a burglar detector that's
mainly because of the orientation of the
source with respect to Virgo well I know
having for the LIGO Livingstone are
almost aligned with each other up to the
curvature of the earth virgo is is in
Italy and so is misaligned with answer
limits and detectors if this thing will
be well aligned for Virgo it would have
been visible in the virgo detective data
but it was near a a dead spot of the
Virgo detectors antenna pattern the
gravitational wave detectors are not
uniformly sensitive to the whole sky and
the fact that we did see a signal in
Virgo given how strong it was in the
LIGO detectors gave us very good sky
localization in fact I think much better
than many was expecting to get for for a
few years on the the next slide this is
the the gamma ray burst signature and
the the gravitational wave signature and
so the probability of a chance temporal
and spatial coincidence of a the
gamma-ray bursts that was seen by the
Fermi gvn detectors an integral is 500th
of minus 8 so we have just from temporal
and spatial coincidence of GW 1708 17
and GRB 1708 17 a we have a 5 Sigma
Association of the the gravitational
wave merger and the gamma-ray burst that
was seen by therming integral and so we
can pretty much conclusively say that
this gamma-ray bursts
short hard gamma-ray bursts and binary
neutron star merger associated with each
other
and the pine delay between the end of
the gravitational wave signal on the
start the gamma-ray burst is 1.74
seconds which is an important number
that the damn numbers we'll talk
about later so we have very quickly an
unambiguous association between a
gamma-ray burst signature and and the
gravitational wave signature so let me
just explain a little bit how this was
discovered so this is the the discovery
scene screen that we see and we very
realized we had a significant signal on
our hands we have a suite of automated
software called GST loud that runs online
looking for binary neutral star binary
black hole mergers and at 8:47 a.m. EDT
it's submit an event that event was
flagged just in the half of detector but
had a very high significance so a false
alarm rate that means the chance of this
coming from noise was less than one in
nine thousand years for this we looked
at it and has a high signal-to-noise
ratio so just in the Hanford detector
its signal to noise ratio the match
filter signals Nora is 14 which is very
large for binary neutron star event and
you can see that we saw quickly the the
load ship mass 1.2 and total mass 2.8
strongly suggests that this is not
another loud binary black hole but is in
fact they a binary neutron star
candidate so very quickly we realized
that this was a possible binary neutron
star source and we also had with we've
plumbed into into Fermi GBM alerts and
we saw that it was a Fermi gamma-ray
burst event two seconds after the merger
so this girl is extremely excited that
we're seeing something allowed possible
binary neutron star event coincident
with a trigger but the tree was only
seen in Hanford even though Livingston
and Virgo were were operating so there
was some level of scrambling to figure
out what was going on when we took a
look at our detector data we realized
that there was actually a glitch in the
in the Livingston detector data at the
time of the signal that prevented us
from the automated software from seeing
it but we went back in with a another
piece of software that does the
reanalysis that looks for binary neutral
star signals
we rapidly reanalyze the data and this
plot shows time on the x-axis and
setting in seconds and match filter
signal noise ratio on the y-axis and you
can see those two beautiful clear peaks
there with a a nice strong Livingston
signal and a nice strong Hanford signal
this was the reanalysis has to be
mitigated the the glitch and the
Livingston detected data so after the
humans went in figured out what was
going on with Livingston it was a
fraction of a second of data was
corrupted compared to this hundred
second one binary neutron star merger
and we saw we had a coincident event in
in Hanford at Livingston you'll notice
that the Virgo signaled noise which is
shown in green doesn't peak within the
time delay window that you would expect
from a Hanford Livingston signal even
though this signal is so strong it
should have been seen in Virgo the
reason for that is as I said before it's
near the dead spot of the Virgo detector
and that gave us extremely good sky
localization so we use the software
called base start to do the to do the
sky localization the bathe the the brown
region shows you the region we would
have got star localization from half and
Linux been alone but with a constraint
we get from Virgo of the absence of
signal bear we narrowed it down to a to
a much smaller region and a small enough
region for electromagnetic follow
partners to Gus that and get it very
quickly in fact we're only limited by
the the location of telescopes and
rotation of the earth we didn't actually
miss anything electromagnetically because
of the delay of doing the data analysis
and mitigating the the glitch so 1:45
p.m. EDT we sent out an alert with with
Sky localization we we refined the event
so the sky localization out liked it as
a very significant trigger at this
luminosity distance of about 40 mega
parsecs which is very close for a very
loud signal and then stopped the e/m
partners to go on that and once you look
about that in a second let me just
briefly review the the premise of the
signal I'm just going to discuss the
individual component masses here Jocelyn
will talk about the implications of the
signal for the for the new to creation
of state this strongly
looks like like a a 1.4 1.4 solar mass
finding neutron star merger
the problem is with gravitational waves
as you may know we don't measure the
component masses very well what we
measure very precisely is the mass which
is that combination and 1 M 2 to the 3/5
M1 plus M2 to the 1 over N1 plus N2
the one fifths that we get extremely
accurately and if you plug in equal mass
ratio there that comes out as basically
one point three seven more point three
seven equal mass but when you actually
try and measure the masses without a
prior on the on the on the on the mass
ratio the plot on the last shows what
you get either for a very coarse eyes
wide open large spin this number Kies
that is the neutron star spin but if you
restrict down to more plausible neutron
star spins you get the the the base
region there and so it looks like this
is an equal mass by a neutron star about
40 mega parsecs I've given the the range
on M 1 and n 2 there the broadening of
the range on M 1 n 2 is because of the
our lack of ability to measure that the
mass ratio compared to the compared to
measuring the mass this slide shows the
the connection to the the gamma-ray
burst one thing to know here this is a
figure from the LIGO Virgo Fermi
integral gamma ray burst gravitational
wave detection paper what this shows is
the the redshift of GRBs
short GRBs and long GRBs with no
redshifts and the the luminosity of
this GRBs the blue or the short  GRBs were the known redshift and the
pink dotted line is approximately the
the sensitivity of the the GBM detection
sensitivity to the GRBs as a function
of redshift
now this GRB was was pretty faint it was
just on the edge of being able to be
discovered given that this sources at 40
mega parsecs so one thing to know is the
the gap between this green star here
which is GRB 170817A and the
rest of the population and this is all
wondering if there's a a faint
population of GRBs out there and
you trust our raters the people
previously thought that GRB
GWs might be difficult to get might be
at large distances or lot large
redshifts but it's looking like there's
actually this this nearby population
that we may get a few more of these in
the years to come
speaking of what's gonna happen in the
years to come this is the figure from
the oh one Barney trust our upper limit
paper that shows the range of
predictions for the binary neutron star
rate in per cubic gigaparsec per year and
the O1 upper limit of what we excluded
from not detecting anything in a warm as
well as the predictions for the possible
Oh 2 and O 3 ranges for future currently
to run and future runs if we superimpose
the measured rate and measuring rate
with one source is always tricky so it
has pretty large error bars but the
measured rate of binary neutron star
defections from gia from GW 1708 17 that
gives us a rate of 1540 per cubic a
gigaparsec per year and is shown in that
yellow region here and this is nice
because the the upper end of most of
these rate predictions it looks like
we're going to be seeing a fair few
these things moving forwards so let me
leave into Malthus talk with this movie
that basically shows the the
localization region from Fermi of the of
the GRB but for me an integral region
using the the data from the integral GRB
detector the overlap of those regions is
that blue area right there in a second
this is going to show the the LIGO
localization so this is LIGO and
then when you add in the Virgo detector
you get this very nice error region here
you can zoom in on this and then this is
the point where the the e/m follow-up
takes over so I will let this movie play
I will stop here and hand it over to
Nancy
thanks very much Duncan for that very
nice talk so if you have questions for
Duncan please put them up via twitter
using the hashtag GW nuclear or send an
email to us at gwnuclear@nscl.msu.edu and so as Duncan said next we're
going to hear from Nancy Cassady well at
Caltech about the electromagnetic
signals observed in 
conjunction with the gravitational waves
from GW170817 so welcome Nancy and
take it away
I'll pick up dust began the most
exciting morning in the life of many
astronomers time domain astronomers in
particular so we started the hunt of
which galaxy it really was amongst only
49 galaxies in this very very well
localized signal and the way we did that
is that we crossed matched the
information from the gravitational waves
on the localization not only distance
but also volume with galaxies catalogs
and then we prioritized our search based
on parameters of the galaxy in
particular the stellar mass because the
expectation is that the more massive the
galaxy the more likely it is to be the
home of the merger so we began searching
down this list marching down this list
with multiple telescopes at multiple
wavelengths and at least at least here
at Caltech we tend to be a little bit
more like gnostic when looking for the
first of anything so we began a
panchromatic hunt at four different
wavelengths and just march down this
galaxies list and so the so this is a
list of 49 galaxies and we began a
search indy hard x-rays soft x-rays the
UV the infrared and radio and then there
were many many more teams doing optical
and infrared searches in particular in
Chile because if you notice the RA and
Dec in the localization it was very
nicely accessible from the southern
hemisphere but it was very close to the
Sun and the first country where the sun
set after the localization was announced
was Chile so there were eight telescope
against adopting different search
strategies different galaxies gas logs
different filters the details but all
began searching in the two-hour window
after sunset to find the electromagnetic
counterpart and within minutes of sunset
the Carnegie observatories a group with
using a very tiny 40 inch telescope
announced a possible Canada's
counterpart you see this bright dot here
that wasn't there before there's a
convenient red arrow which didn't come
you know with the with the image when it
came
and they were the first to announce the
coordinates and this was fantastic
because within minutes of this
announcement and this is one of the most
majestic aspects of this discovery was
that within minutes of this announcement
there were the sections of this
electromagnetic counterpart in the
ultraviolet but a swift satellite and
the infrared in them in the optical at
least in these three big bands all
within a day after merger and what was
spectacular was that even after much of
a wait which was about nine days and the
x-rays and sixteen days in the radio
even the x-ray and radio emission was
detected from this electromagnetic
counterpart so there was light at every
wavelength and that to me is just
scientifically amazing because it gives
you information to put together a
complete Astrophysical and Astro
chemical picture of what what we were
seeing here and this was a global effort
by many many telescopes actually I think
it was total of 70 telescopes worldwide
including seven telescopes in space and
adding every continent there's even a
telescope in Antarctica that was
observing and this little movie here
that you see you can see time ticking on
the top right and as the Sun sets in the
different countries you see the optical
and infrared telescopes observing the
green dots are radio and you see that
the radio lights up even in the daytime
because radio is immune to the Sun but
this is a spectacular effort with I
think two or three thousand astronomers
involved and on the day of the
announcement there were 84 papers and
archives describing the electromagnetic
counterpart and how it relates to the
gravitational waves this discovery of
the first binary neutron star merger of
course one other advantage of having a
globally distributed team which I'm
lucky to have here is that the team
never sleeps you know the Sun never sets
on the telescope they keep observing but
the team also is is is continuously
working and there's a lot of excitement
and in this team how you just see
pictures of the real powerhouse of such
teams
the young students and postdocs looking
at the data as soon as it comes in each
one taking ownership of one of our 18
telescopes that were involved here and
I'm reducing the data as soon as it
comes and triggering the next
observation because this transient was
full of surprises
this is the first time we were seeing
something like this unfold so everything
had to be done dynamically in real time
in terms of triggering telescopes
planning and optimizing search
strategies and the young people the
students and postdocs really played a
key role here so this year now is a
compilation of the ultraviolet optical
and infrared light curve so you can see
that the ultraviolet light fades very
very quickly it's gone in just a few
days this is data from the satellite and
these main points here from the Hubble
Space Telescope you can see the optical
lasts for a few more days and about
eight week or so and the infrared the
jhk bands these are the near infrared
bands they evolve relatively slowly for
a good three weeks or so and and you can
now combine this to form a volumetric
light curve but one thing is already
clear at this point is that the
strontium was very bright and very blue
at early times and while this is
puzzling from explaining from model for
point of view this makes observers
really happy because bright and blue
means easy to easy to find and so that's
good news of course one of the
astronomically one of the most
spectacular aspects of this discovery
was the nucleosynthesis and
understanding our crosses
nucleosynthesis so as of august 16th we
knew that hydrogen and helium come from
the Big Bang the elements shown in blue
here comes from different flavors of
supernovae but until August 17th we had
no idea we fed of a lot of our
predictions but people such as Jim
Latimer decades ago theoretical
predictions that please where our
crosses nucleosynthesis and the place
where all these heavy elements shown in
yellow here are synthesized should be
merging neutron stars but for observers
you know seeing is believing and this
event was a first
opportunity to see two neutron stars
merge and it was actually quite amazing
that we could also see evidence of
artosis nucleosynthesis and and the
formation of these heavy elements so
here I show you the first spectrum that
that my group took it took a Gemini
Observatory and my super my students
would you suspect I couldn't believe it
there were these two broad bumps that
you see here in the spectrum that's the
data and green black smooth and in red
you see model predictions from Dan
heesun and Jennifer Barnes from four
years ago this is not fitting the data
this is just over plotting Dan and
Jennifer's work and these are prediction
for what our fastest nuclear synthesis
elements in a radioactive decay if you
take into account all the paths cities
correctly look like and it was really
very very surprisingly close so hope Dan
will tell you more about this and
there's a beautiful spectroscopic
sequence here I'm showing you a sequence
taken by my collaborator Lenape on with
the Very Large Telescope of the ESO
Observatory the Orkin Observatory and
you can see as time ticks you see the
spectrum evolved from something very hot
and blue to something which starts to
show bumps and Wiggles which are
probably blends of many different
elements the guesses are starting to
trickle in in the literature and Dan can
tell you which ones do believe and which
ones need a lot more work in the next
talk but you can see that there's a lot
of information at almost one-day seasons
all the way from the UV optical and
infrared of how the spectra evolves as a
function of time and the data collection
continues because even after the saga
became very close to the Sun the
cultural be detected with the Spitzer
Space Telescope and this now is probing
the reddest emission and also in the
nebula phase so has additional clues on
the nuclear synthesis and what I hope
some of this audience will be experts in
is again the the distribution the
relative abundance of these elements do
we really need all three peaks to
explain this is the amount of material
that's made here multiplied by the rate
equal to the solar abundance the paper
by Stephane Ross
which says that we just need the first
pink in the second peak maybe a little
bit of lanthanides would help but we
don't need the third peak at all to
explain the data in hand so I think all
of these open questions and I think the
many I know this is the beginning of of
trying to understand all these puzzles
but I wanted to take the last couple of
minutes just to give you a sense of an
Astrophysical picture of how we can put
together all the different data the
different wavelengths to explain what we
are seeing and there's some other form
of a misconception that you know what we
are seeing is a gamma-ray burst it was
not on axis I think everybody agrees
that it was not on axis but as duncan
showed you it was a very very weak burst
of gamma rays so it's almost misnomer to
call it the gamma-ray burst because it
was ten thousand times weaker than a
typical shorter gamma-ray burst and the
debris view and x-ray was really a very
very long and patient wait a
surprisingly long and patient wait and
it has a very surprising signature which
is at odds with the gamma-ray signature
so it whether you talk about an own axis
or slightly off axis GRB you need it to
be slightly off axis explain the gamma
rays but the video and x3 are required
to be widely off axis so the canonical
picture of an ultra relativistic jet
just doesn't work so one idea one of you
know many ideas I hope that people will
be thinking of to explain what we are
seeing here is the idea that we proposed
called the cocoon breakout and idea here
is that on the left you see the
energetic CC energy density on the right
you see the log for velocities you see
the velocity and kinematics so as the
jet launches basically the pointers of
the jet is not launching in a clean
environment the jet is launching now in
an environment where there has already
been several senses of solar mass of
material thrown out into the surrounding
medium even before the module so the jet
simply gets stuck and the structure
transfers a lot of its energy into the
surrounding circumstance force energy
gives rise to what we call a cocoon of
emission
and when the cocoon breaks out of the
material because this cocoon is only
mildly relativistic the Lorentz factor
of two to three instead of a Lorentz
factor of 100 and it's very very wide
angle it can easily explain the low
luminosity in the gamma rays it can
explain the time lag between the merger
and and a subsequent burst of gamma rays it can explain this long wait to see the
radio and x-ray emission furthermore
this cocoon because it's accelerating
all the heavy elements and all the
materials here
thus acceleration just by Doppler
effects can explain is one of the ideas
to explain the early blue emission and I
hope Dan will give you a yet another
idea to explain that only blue emission
that was somewhat of a surprise was a
little bit to uncomfortably price I
would I would say and the model works it
can explain the volumetric luminosity as
a function of time the temperature is a
function of time velocities are few
tenths of speed of light of the ejecta
that's velocity is a function of time
radius one thing that remains an open
question of season October 16th was what
is the fate of the jet did the jet get
completely choked by this cocoon or did
the jet transfer some of its energy but
escape in another direction so if you
had a friend on a different planet that
was looking at this from a different
line of sight down the barrel of the jet
maybe they would see an ordinary
gamma-ray burst the way to answer this
question is really the radio and the
x-rays because the the speed and the
width of the the jet versus the cocoon
gives a very different signature in
these extreme be fans and here's a radio
light curve as of October sixteenth
and it was consistent a very wide off
access jet as well as possibly cocoon
and stay tuned because in just a few
days you see a few more points on this
light curve which which seem to be very
consistent with with this idea of a
cocoon furthermore you can use the
network of radio telescopes around the
world to directly measure the
of the ejecta and the size of the ejecta
is obviously again just a function of
speed and here is size relative to the
solar system and just by putting a ruler
you can measure the size and distinguish
between an ultra relativistic jet on
axis of access doesn't matter and a
cocoon which is mildly relativistic and
much wider angle so I'd like to conclude
with a NASA animation of how the whole
model holds together it's a cartoon but
it's a fun one so you can see the
neutron stars coming so the tidal tails
all the material being filled out into
the surrounding medium the merger the
jet being launched the jet being sucked
the cocoon the blue emission then
quickly becoming red and then this
forward shock that's giving you the
radio and the x-rays and with that I'd
like to hand over to to Dan Kayson so he
can tell you more about what we've
learned from this dataset Thank You
Monty so if you have questions based on
Monty's talk either tweet them to us
using the hashtag #gwnuclear or by
sending email to gwnuclear@nscl.msu.edu
and so like Monty said next we're
gonna hear from Dan Kasen about
interpreting electromagnetic
observations or more interpretations so
take away down great thank you
so yeah we've gotten a great sense
already about the exciting science
that's come out of this event and I'll
tell you a little bit more about one
piece to that which is how the optic on
infrared emission I can tell us a little
bit about this question of the origin of
the heavy elements in the universe and how
they may be reformed in some significant
part in these kind of neutron star
merger events it's one of the
long-standing questions in astrophysics
actually where all the stuff in the
universe came from this plot showing
basically the distribution of elements
that we find in our own solar system and
there's a lot of stories to tell early
in the universe
big bang there was really only hydrogen
and helium and and everything
essentially heavier than that was
produced in stars and different kind of
stellar explosions massive star fusion
and in core collapse supernovae
thermonuclear white dwarf explosions
producing the iron group but all the
elements above the iron group have been
one of the big open questions for many
years and pretty sure that to make them
require some process of neutron capture
which we'll talk about in a in a little
bit more detail in some part a slow
Neutron capture in other cases a rapid
neutron capture in our process but
exactly where this our process events
happened in the universe has been one of
the big questions for many years is it
something in supernova does it involve
neutron star mergers or some other sort
of event and you can see these are very
you know above iron is a very small
fraction of the total amount of elements
in the universe but they're very
interesting fraction I mean this
includes all the precious metals like
gold and platinum radioactive isotopes
like uranium and rare earth elements and
a lot of other interesting things so you
know in the past we've been basically
relying on the fossil record of those
heavy elements to try to decipher their
origin now this new event we had a
chance to see some of that material
being made in its site in one of these
neutron star mergers and a lot of this
before that was based upon theoretical
ideas of how material might get ejected
in the neutron star merger
Montse showed a nice simulation at the
end which was too early just a cartoon
picture but you can actually calculate
the merger physics in some detail by
trying to model the relevant physics
involved and that involves a suite of
physics really hydrodynamics of these
two stars coming together some
information on the nuclear equation of
state that Jocelyn will tell us more
about a treatment of gravity general
relativity neutrino physics and nuclear
reactions which all go into the picture
and of course it's hard to put all that
into one single simulation so most of
the calculations are done using
high-performance computing but still
approximating some of the physics
involved but I'll show you one example
here this is a simulation by Stefan Roz
walk showing a calculation of two
neutron stars coming together and you
see them basically starting to merge
together into one merged object but you
also see some material getting flung out
in the merger itself so most of the mass
90% is going into that central object
which could be a massive neutron star
but it's likely to collapse into a black
hole whether it does so it depends upon
some physics that we don't fully
understand really how massive the
neutron star can be before it collapses
into a black hole and that depends upon
the equation of state and some other
physics that we hope to learn more about
but in any case you see there's you know
maybe a few percent of the material it's
just flowing out of the system maybe
another few percent or up to ten percent
is in a disc that more gradually
accretes onto the central object now and
may have something to do with the
gamma-ray bursts that Muncey talked
about so just a little more detail about
how you might get stuff flown out in a
neutron star merger which will
eventually lead to the optical infrared
light that we think that we have seen
now there's three different ways in
essence of how you can do that and you
know in the merger it sounds like you
just saw you can have material that's
flung out just dynamically this will be
flowing out at a few tenths of the speed
of light weight to 0.3 C it'll be cold
very Neutron rich maybe 10 neutrons per
every proton or more and that's because
you're basically just taking pieces of
neutron star and fleeing them out into
space but there's another way you can
fling a matter in the merger itself and
that's as this two stars collide
together there's a shock at the
interface and you can squeeze out
material from that shock into the polar
regions and that material will be hotter
as of the shock and it'll be less
neutron rich because they'll be weak
interactions neutrino interactions that
can change neutrons into protons and you
get something someone who less Neutron
rich which has a big impact on the kind
of elements that get produced from that
material and then after
the merger you know seconds afterwards
so a long longer time skill you have
this disc that's reading onto the central
object maybe powering the gamma-ray
burst but some of that material that
just can also be blown away in winds and
you can actually get a lot of material
coming out after the merger itself maybe
even more material than during the
merger itself and that will be moving a
little bit slower maybe less than a
tenth the speed of light and it'll be
hot and maybe have a range of
neutron richness so what becomes of this
stuff that you fling out in this neutron
star collision well I'll show you sort
of a cartoon picture and then show you
some more details equations calculations
and so the basic idea goes back to work
by two monomers
on panel here today that when you fling
on material from a neutron star
originally it may be quite exotic inside
the neutron star but it probably quickly
as a decompresses decomposes into free
nucleons neutrons and protons and we
expect more neutrons than protons in
this environment and then as expands and
cools the neutrons and protons will
combine into two alpha particles helium
nuclei and so you'll have some of those
with some excess neutrons left around
those alpha particles will then fuse
together into two heavier nuclei I would
call seeds so these probably go up to
maybe the iron group but not too much
beyond that before you stop being able
to fuse and then the process that goes
on from there is this process of Neutron
capture where neutrons bombard these
seeds and stick to it and grow to
heavier and heavier nuclei in that
process neutrons afterwards being a
dedicated protons and you build up
nuclei that way and so the more neutrons
you have foreseen the heavier you can
build up your elements here's a more
detailed calculation of that that
process is our process this is work with
the by Jonas Lipitor and Roberts our
moderator now here's a chart of the
nuclei so basically all the nuclei is we
think that can exist in nature and
number of protons and the number of
neutrons and the square boxes you see
there are the stable nuclei that we see
around us
so this calculation shows the flow that
I just cartooned in the last slide of
nuclei is starting from some C nuclei
shown in red there around the iron group
and then progressively as we capture
neutrons and then beta decay to protons
this flow builds up very far from the
region of stability it builds up to the
very heaviest elements where it may
fission and cycle back down but in a
process of a few seconds it builds up
into these heavy elements and then it
may take you know days weeks months for
it to decay back down to stability as
you see here so one of the key issues
that in trying to understand this flow
and how these elements are formed is the
nuclear physics of what the rates are
for different processes and that flow
with the masses are of the nuclei and
since all this happens very far from
stability from the nuclei we easily have
in the lab it's hard to know much about
that exotic region away from nuclear
stability so that's done in various
accelerator experiments and you can see
here in this plot showing the same chart
of the nuclei the colored regions
showing regions that we know some
something about but what we'd really
like to know is is the properties very
far from stability and so that's what
various experiments are working on
including the the Facility for Rare Isotope Beams being built at Michigan
State [University] is going to try to get us
information on that red region all the
way out into this very Neutron rich
region far from stability and that'll
make a huge difference in our
understanding of how those heavy
elements build up and how we can
understand and extrapolate even to
further regions away from stability so
what you get out of those calculations
in terms of the abundance of elements
produced it depends both upon those
nuclear inputs and upon the conditions
that you have in the ejected material
from the neutron star merger so at the
top it's showing a basically calculation
of the distribution of elements of
different masses each of these colored
lines
different theoretical model of what the
properties are of those very unstable
nuclei and you can see there's some
robust features in terms of the peaks in
a mass abundance distribution but
there's some significant differences in
particular at the very heavy end how
much material we make in the
distributions in between and those can
have important impacts on what we see
from the neutron star merger and it's
aftermath in this mission and then the
bottom plot showing you how important
the conditions in the ejecta are in
determining what gets made the red and
black lines are a material that we
rejected and it was very Neutron rich so
it built up into two heavy elements
basically stuff heavier than a of 130
the cyan line is material that was less
Neutron rich and it only made it up to
be MEA of 130 but has mostly producing
nuclei in the in-between regions and so
here's kind of a schematic picture
that's trying to synthesize MeV you know
hundreds of papers of work around the
world that people trying to simulate
these mergers and their nucleosynthesis
and you get a generic picture that might
look something like this where in the
equator you'd have these tidal tail
ejecta which this Neutron rich and
produces very heavy our process nuclei
well in the polls you may have this
squeezed hotter material that is less
Neutron rich and makes will be lighter
nuclei and then there may be some winds
moving more slowly coming from that
region around the merged remnant that
produces maybe a range of different
nuclei depending upon conditions there
so that's theoretical ideas but what's
amazing is now with this new event we
can actually see directly and probe that
material that got ejected and that's the
idea going back to Lee and Wyszynski and
also revived by Brian Metzger and
Roberts that the material here is
radioactive that gets ejected and we can
see that glow so originally the material
is quite compact but it expands rapidly
it's moving and you know a few tenths of
the speed of light after about a day
it's grown from you know neutron star
scales all the way up to something the
size of the solar system so you have a
very tenuous
cloud there but material and it's
highly radioactive we sort of these
unstable Neutron rich nuclei that are
beta decaying back down to stability if
you have some of the heaviest trans led
nuclei you can have significant fission
than alpha decay if there's free
neutrons you can have a neutron decay
all these processes are going on in
heating up this big radioactive cloud
which is going to be radiating it's
something like ten million times the
luminosity of the Sun just from its
radioactive glow that that brightness is
about a thousand times the brightness of
a nova in our own galaxy so that's what
coined this term villanova it's somewhat
right but it's compared to a supernova
which we see more often it's maybe ten
or a hundred times tumour so it is quite
difficult to find and the temperatures
is somewhere around five thousand Kelvin
or something not so far away from the
temperature of the Sun so it's rating
visible light and infrared light and so
from that physics you can model actually
what we think the light curves and the
spectra of these events should be here's
some calculations down with Jennifer
Barnes showing that what we see is
actually quite dependent upon what the
composition of the material is so the
red line here on the Left showing you a
light curve if the material was made out
of the heavier our process elements and
for atomic physics reasons that material
is quite opaque and we get a very long
lift maybe a week-long transient due to
the long time it takes photons to
diffuse out of this very opaque cloud of
debris whereas if you have light our
process elements you get something
that's somewhat brighter and briefer
because do pass these are significantly
lower and that plays out significantly
in terms of the colors of the spectrum
that you see if you have these heavy
elements the optical regions are
blanketed and you seamless the emission
mewn thread if you have lighter elements
you see what's the emission coming out
in the optical so the color and the
timescale of the emission that months we
talked about is sort of a direct probe
of the composition
that we're seeing in Muncie showed some
comparisons here's just a simple picture
of what we think we might be seeing in
the data that she and others took in
early times we're probably seeing mostly
maybe the squeezed polar material that's
lighter maybe two percent of the solar mass
of that that's producing mostly
short-lived blue emission that fades
away quickly and then at later epochs we
may be seeing heavier elements that give
us a redder emission that lasts for
longer in a few weeks or so and in that
way you can provide reasonable fits to
the coloring and brightness of the event
we see when can ask you know what in
more detail what do we see here
once you show that comparison of a
spectrum use another comparison of the
observed infrared spectrum to one of our
models and you can see some agreement
there when we'd like to go further and
try to extract details about what the
composition is of the material in detail
that's hard to do because the features
that you're seeing here the engines are
not from any one specific elements
they're really a blend of lines from
many many different elements but there's
still information to be teased out of
here as you change the abundances you
change the locations of these Peaks and
so we're starting a new era we're gonna
have to learn how to inspect or stop
eclis and analyze this material and pull
out details about what exactly that
we're seeing so this was a really
exciting event it was really the first
time we were in the probe and directly
measure the amount of heavy elements
produced in an event and it's really the
first time we've confidently or fairly
confidently been able to say we've seen
the production of our process elements
and you can ask if there were enough our
process elements to explain everything
that we see in the galaxy and there's
uncertainties in terms of the rates that
Duncan mentioned and in terms of the
mass is ejected but basically order you
know back the envelope calculation it
was enough material produced to explain
the bulk of the heavier
well as we hopefully see many many more
of these events to get boats
gravitational waves an electromagnetic
data will have a better sense of what's
going on and I expect that we'll see
diversity because the material that you
eject depends upon several things the
mass of the stars involved whether
they're by neutron stars or black holes
with the equation of state the Justin
will tell us about is and again there's
nuclear physics inputs so we may get a
range of different behaviors that we can
start to understand with a rain a
different sample of objects and as you
can imagine the objective material is
not quite symmetric so as we look at
these events from different viewing
angles we might expect to see different
amounts of emission depending on which
we're looking and what's incredible is
that with the gravitational wave data we
get some information about what the
orientation is of assistance we can
virtually fly around these Killa Nova
look at them from different points of
view we get information about what the
masses are as well and we can start to
put together a detailed picture so I'll
just leave with kind of this general
sense of what's going on here it's kind
of remarkable on the theory side we're
connecting
physics across all these different
scales all the way from the nuclear you
know subatomic scale to the stellar
scale mergers to the lactic scale of the
formation of elements and then we're in
a special time where we have these
amazing facilities that are probing
nature on all those scales the effort
probing what's happening on the nuclear
scale LIGO and astronomical surveys
probing the merger scale in the
production of elements so it's really
just the start of an exciting time and
it should be really interesting to see
what happens in the years to come
excellent thanks Dan
if people have questions for Dan and if
you're just joining us now you can ask
questions via twitter using the hashtag
GW nuclear or using the email address GW
nuclear MSC l msu edu so the Killa Nova
and our process production
is one sort of very exciting aspect of
this event but the other exciting aspect
for nuclear physics is also what we can
learn about neutron stars themselves
from this event so our next speaker is
going to be Jocelyn Reed at Cal State
Fullerton and she's going to tell us
about what we can learn about the
properties of neutron stars from this
gravitational wave signal so thanks for
coming Jocelyn
take it away thank you very much it's
really great to be here this morning so
let me just set up my slides and as and
as I prepare so I'll give you a picture
of what we're learning about this event
from the gravitational wave side of
things itself so mapping from the data
shown in the bright green curve here
that duncan talked about earlier back to
the properties of the source itself the
binary neutron star merger seen in the
top left so just to set the scale for
those that might have been joining
compared to something like our black
hole mergers that we've observed already
and gravitational waves this is
observation of a different scale order
of a hundred seconds visible and the
gravitational wave data band not visible
by eye per se but compatible with our
our analysis algorithms so over
thousands of cycles of of the two
neutron stars orbiting around each other
stirring up the gravitational waves and
measuring that evolution in their
frequency over time we are able to infer
the properties of the component stars
that that generated the gravitational
wave signal so this Duncan said tells us
some things about the masses and spins
of the component stars so this is just
the mass of the more massive component
and the less massive component we very
precisely measure a combination of these
masses the chert mass and then we find
that this is compatible with an equal
mass system of very typical neutron star
masses
scene in galactic observations but due
to some degeneracies in the
gravitational wave signal between the
mass ratio and the spins of the signals
we have a lot of uncertainty in the
exact values of the component masses so
we can make some Astrophysical
assumptions about the spin of the stars
this is a low spin system compared to
the binary black holes we've observed if
we restrict to quite small spins which
is indicated by the blue in this plot we
get mass ratios that tighten up closer
to the equal mass system one might
expect from looking at at neutron stars
in our own galaxy but what I really want
to talk about mostly today is using this
gravitational wave observation as a sort
of a Astrophysical scale Collider that
will tell us about the dynamics of these
two dense objects as they approach each
other and even before they collide and
that allows us to probe sort of the the
phase space of dense matter in a
different way than most of our earth
bound collisions can give us access to
so neutron stars are not sensitive to
temperature when they're isolated but
after after they've cooled from their
initial formation they're relatively
cold we expect them to be in equilibrium
so that's probing a cold dense matter
region of the parameter space until they
collide in which case that dramatic
event can increase the temperature and
start to give some hints of other other
aspects of dense matter physics but as
as Dan introduced most of what I'll be
talking about that we learned from
observing the dynamics through the
gravitational wave signal is the
properties of dense model matter in beta
equilibrium the cold equation of state
at and above nuclear density that
determines the properties of the neutron
stars so given a mass of a neutron star
this tells us the radius that
deformability of the star
and also leads to the maximum stable
mass that determines some of those final
fates of whatever merged object was
produced by this signal so to look at
the impact of matter on a gravitational
wave you can start with the
gravitational wave forms stirred up by
just two point particles things that do
not have matter scale a radius that's
that's significant more similar to what
we see for black holes and it turns out
that most of the in spiral so this
central panel here is just zooming in on
the last two seconds of that order one
hundred second signal
recorded by the gravitational wave
detectors starting around two seconds
before merger when the objects would be
roughly sort of a hundred kilometers
apart orbiting each other 100 well
orbiting each other 50 times a second
and then over the last seconds they fall
together orbit more quickly and then the
final fractions of the second you see
this more characteristic chirp pattern
as the stars collide now if I put try to
put matter in this in this scenario of
the first thing we'll notice is that
looking at sort of the top panel the
early in spiral dynamics are primarily
determined by the masses and spins and
those are going to be very hard to
modify but the final fraction of the
second will be be modified if I
introduce the differences when the
neutron stars have a finite size that
modifies their interaction so I'm going
to add in matter to the bottom panel now
and there'll be two effects so the first
thing is that at the start of that
bottom panel there's a small shift the
tidal interactions of the stars have led
to an accumulated phase shift at the
higher frequencies and then the final
stages of the merger are driven primarily by their matter affects the
Stars eventually crash together at a
frequency that's very sensitive to how
large they were that limits how far they
can fall in so what we're going to do is
use these properties of the neutron
stars to map back to the dense matter
that generated them so there's there's
sort of two features and this in spiral
effect is actually what we have so far
used to learn about neutron stars from
the August detection so as the stars
deform each other through tidal
interactions that takes energy away from
there in spiral and accelerates them
towards merger the size of this effect
is determined by a combination of the
radius the size of the stars two to the
fifth power so this is a radius
interaction that becomes very
significant when the size of the stars
approaches the size of their orbital
separation and there's also a Love
number this k2 here in this in this
formula presented which it can be
considered a reflection of how centrally
condense the stars are which will affect
how deformable a star of a given radius
is how much how much the tidal
interaction changes the gravitational
potential and so on the bottom we see
this equation of state of cold dense
matter above nuclear density with
different pressure scales as the
pressure increases the radius of the
neutron star increases and the
acceleration of the in spiral shifts the
merger to earlier times now this this
green scenario here is is quite an
extreme scenario and that's actually
going to be disfavored by our data
analysis of the neutron star merger so
just to close the picture in terms of
what I'll talk about today if we compare
the merger of compact stars which I'll
start on the top panel
these are going to be stars starting at
roughly the same separation that the top
panel is more compact stars the lower
panel as larger radius stars the larger
radius stars are already hinting at
titled information you may be able to
see in this panel and just focusing in
on their final orbits and merger will
see that the large radius stars deform
or accelerate they're in spiral they
collide while the compact stars can
still orbit and so that the merger
happens a little earlier now this these
demonstrations are also showing some
very very some variety of scenarios for
after the stars collide whether they
collapse to a black hole promptly
whether they live as some sort of hyper
massive object before a collapse it's
also possible that they could have had a
long-lived neutron star remnant that's
at least in terms of the gravitational
wave data not visible because the high
frequencies of a post-merger signal are
hidden by the detector noise although
this may with future upgrades to the
detectors no longer be true so what does
this tell us for the particular
observation so I'm showing a plot from
our discovery paper where we talk about
the component stars the smaller star and
the larger star and a measure of how
deformable each star is with a
particular assumption that the spin is
not so large and a waveform model that
we've determined is as actually recovers
reasonable parameters even though it's
quite a simple waveform model when
compared with more sophisticated
analyses so we allow the deformability
of each of these stars to vary we see
which parameter values best match the
data in concert with the variations of
the masses and spins and we see that
17:08 17 supports lower deformability
stars with a 90% limit
in this sort of diagonal line the to
deform abilities are the the the
properties recovered are correlated in
their impact on the gravitational wave
form so similar to a chirp mass you can
consider a sort of a chirp lambda that
map's along these these contours here of
how how we recover the properties of the
Stars now we can compare these two
equation of state predictions generated
by taking the recovered masses of in
spiral applying an equation of state
that maps those masses to the deform
abilities compatible with that starting
with the equal mass case where the
deform abilities are equal and sweeping
up with the mass ratio of the two
different stars and this shows that some
equations of state are over all ranges
of the masses we consider distinct from
our supported region it's also worth
noting that we can't confirm here from
the gravitational wave signal alone that
the stars are not more compact than
neutron stars might be expected to be we
have so far only upper limits on the
size of the star which increases their
deformability or their or has a less
compact star but roughly we can map
these equations of state to the radius
of their associated stars and sort of
the equal mass limit and we see that the
90% limit is roughly along an equation
of state that gives order 14 kilometer
radius for the neutron stars so we're
supporting more compact neutron stars
with this observation and some work by
the LIGO and Virgo collaborations
continues to rien a lie and reanalyze
the data of the same gravitational wave
signal with some careful systematic
estimates and linking that the
properties of
stars with equation of state assumptions
and so we think we may be able to say
more in future with with this ongoing
analysis so I'll wrap up with exciting
thoughts about where we might be going
in future with this so as Duncan
mentioned in the first talk this first
observation has hinted that neutron star
mergers are not rare that for example in
a year of observation we might get order
40 events and with advanced LIGO design
sensitivity that would lead to equation
of state constraint that here on this
left panel is sort of an injected
equation of state say for this family of
recovered events and then this blue
contour here is a 95% confidence region
on that equation of state that is
separating it from other equation of
state candidates that only have
relatively small variation in in the
overall pressure predicted by the
equation of State on the right panel is
an implication for radius constraint
implied by this combination of
gravitational wave observations alone so
we're hopefully in concert with other
equation of state implications like
those that Dan talked about where you
can sort of infer again from the
equation of state how much matter might
have been injected in its properties
through careful numerical simulation and
of course the whole other array of
neutron star observations in progress we
hope we could be entering an exciting
era of precision nuclear physics on the
Astrophysical side too
so hopefully we'll now hear from some
other folks about about how that
translates into the nuclear physics side
of things excellent Thank You Jocelyn
yeah so if you have I have a
couple of questions for Jocelyn during the
talk but if you have any more please
tweet them to us at the hashtag #gwnuclear
or email them to us at gwnuclear@nscl.msu.edu so next we're gonna
hear from Artemis Spyrou here at Michigan
State University about opportunities for
terrestrial experiments that can help us
to understand the properties of these
events in particular our process and
maybe nuclear equation of state so take
it away harness
Thanks look thanks everyone I'm really
excited to be here so my plan for the
next few minutes is to try and dive
deeper into the the details of the the
nuclear physics and try to to show a
little bit of which nuclear properties
are more important to help us interpret
this interpret better these observations
of interest or merger event so start
with the same movie that the Dan showed
before but I want to focus a little bit
on on a different aspect on the nuclear
physics properties here so it's done
mentioned the the the boxes here at the
center are where the stable isotopes are
and then there are a few lines on this
plot that correspond to what we call
shell closures or we also call them
magic numbers so for the non-experts
these magic numbers if a nucleus has a
let's say a magic neutron number it
means that it wants to stay to keep that
neutral number and it doesn't want to
sorry it doesn't want to change it to
add more neutrons to remove more
neutrons so this is a basic nuclear
physics property and it's amazing how
this connects and affects the abundances
that we see around us all over all over
the universe so let me start the the
movie here and you can as the the flow
there are process flow goes up you can
see how matter accumulates as soon as it
meets one of these magic numbers and
then heavier into this other magic
number so you see the more intense
regions where just exactly because of
the property of these magic numbers it
tend to accumulate more matter and that
then later in the decay after the the
decay happens these translates into the
the peaks that we see in the abundance
distribution so this is just an amazing
connection and one-to-one connection
between the basic nuclear physics
properties and what we see in the the
stellar observations and this is exactly
one what I want to
for the rest of the talk another thing I
wanted to point out here is that
mentioned the two components that were
observed in the new discovery and though
there was a blue component that was more
lighter with lighter elements and there
was also a red component that showed up
with heavier elements okay there yeah so
we if I put those components on this
chart of nuclei again we know where to
focus on and the exact extent of this
these circles can can be a little bit
different
but the main point as Dan mentioned as
well is that when we see these
components we don't know exactly the
contribution of the different elements
in the inter distributions so in order
to model and interpret what we see in
the observations we really need to go
deeper and understand the nuclear
physics properties that go into these
calculations so let's take a quick look
this is a cartoon version just for the
non experts to understand a little bit
of what kind of nuclear properties are
we talking about so I'm zooming into
part of the chart of nuclei and then
zooming further into let's say an art
process path where the main things that
are happening are either a neutron
capture like dan mentioned before I
wouldn't this way or you could have a
better decay that would move this way
these are the most basic competition
here between the two kinds of reactions
and so depending on which one wins the
reaction flow will will take a different
direction now of course this is a
simplest case you could also have better
delayed Neutron emission which means
that you move one nucleus over one less
less Neutron which this process and
reaches the environment more neutrons
because it emits neutrons and also ends
up in a different nucleus so when you
decay back to stability you will end up
at a different mass another important
thing here is that you could also have
gamma and reaction so the inverse of the
and gamma and this happens if the
environment is very hot so for the two
components that
has been talking about one is a hot
environment the other ones cold so for
the hot environment you would expect to
have a gamma and and gamma equilibrium
but for a cold environment this might
not be the case in which case the
neutron captures become even more
important so let's look a little bit
closer or not all these properties so
the properties I mentioned already are
listed here at the top so we need to know beta decay
properties we need to know Neutron
captures as part of all of this the
masses are very important of all these
nuclei and then I didn't talk about it
earlier but fission is very important
fusion properties neutrino interaction
rates and of course the equation of
state so we need to know all of this
let's see a little bit about what we
know already so the the chart of nuclei
as shown here has kind of again a
simplistic art process path and then the
the reddish color shows how far we can
reach or we've already reached with
current facilities so these are the
measurements of masters and half-lives
of nuclei that we can do right now or
we've done already right now and you can
see that we are touching a little bit on
the r-process path in some regions but
for the most part we're not really there
yet we're not reaching the whole art
process path yet and this line that's
kind of heated on the back here is where
the the next generation facilities are
going to reach FRIB and I'll talk more
about FRIB later I just wanted to
point out that with FRIB we will be
able to reach almost all nuclei involved
in the r-process okay so we don't have
data right now for this nuclei but maybe
we can do good enough with theoretical
calculations so let's say see if this is
the case well the short answer is no
where we really need data and to show
that I have just three examples here at
the top corner I have masses it's three
different mass models I'm not going to
go into the details but what that
picture shows you is that in the region
here where you do have data on mass is
measured masses the different models
agree with each other but
soon as you go further away from the
known data then the models just diverge
and so it's impossible to know if I
should use this model for my approaches
calculations or if I should use this
model and it's really important to do
these measurements to get experimental
data similar stories for the neutron
captures Char Dham nuclei here the color
code is again this divergence variation
between the model predictions and the
red color is a factor of a hundred so
again very quickly you can see that we
get two factors of a hundred or even
more uncertainty in these predictions
I'm very similar for the half lights as
well so it's important that we clearly
don't have a very good understanding of
these properties let's see how these
effects the the abundance calculations
now the with the neutron star merger
observation this is now great because we
don't have to run the 50 or 100
different scenarios and figure out for
each of them which nuclei are more
important or what is the impact we can
now focus on this one the neutral merger
scenario and this doesn't mean that this
is the only scenario that can contribute
but at least with this one we have very
good observations and we can constrain
much better so the two plots here show
the top one is from varying the masses
of nuclei within the theoretical
uncertainties and then the bottom one is
lowering the neutron captures again
within the theoretical those variations
and so what you can see is that the
abundance predictions coming out of
firing the masses and the neutron
captures is quite a broadband so we
don't have a very good handle of these
predictions unless we narrow those bands
down and we can only do that with
getting more experimental information so
we need more data
that's the the main message but there's
thousands of nuclei involved in this and
they in the art process and we we don't
expect to be able to measure every
single one of them so we really have to
focus on identifying the most important
ones and this is done already using
sensitivity studies this particular
sensitivity studies for Neutron capture
rates for and use for certain merger
scenario and the darker the color the
the more important that Neutron capture
is and so you can see that it's not
everything we don't need to measure
everything we can focus on particular
regions where these neutron captures
matter more and the other amazing thing
is that if you see the blue the black
line which is how the Ephrem reach that
we expect all of these important nuclei
are within every bridge so we're really
excited when we can do this measurements with FRIB okay so we we are already
very busy running experiments we're not
just sitting around waiting for FRIB
there's a lot of measurements already
happening around the world many
facilities where we're measuring
important our process properties I'll
just show you a few examples I can't
show everything but I'll just give you a
flavor of what's known what's measured
so for example here I have Argonne
National Lab at the Cariboo facility
they did a lot of work measuring masses
so we have a lot of new masses from that
from those experiments and at the rican
facility in japan they did a lot of work
measuring new half-lives now these two
quantities are quantities that we can
measure directly if I want the half-life
of the half-life of a nucleus as long as
my facility and provide that beam I can
go and measure this property directly
this is not the case for all properties
however the the most difficult one is
Neutron captures even even if I do have
the beam available at my facility I
still can't go and measure directly the
neutron capture just because I can't
make a target out of that short-lived
radioactive nucleus and I can't make a
target out of a neutron it's a pure
technical difficulty but it's a very
important one because if we just kind of
measure these reactions directly but
we're again trying to figure out
solutions to this problem so instead of
measuring this reactions directly we're
figuring out ways to get information and
get them indirectly
so there's at least two interact
techniques that especially in the last
few years they've been developed a lot
one is called the surrogate technique
and this is simply in it's shown in this
graphic here where instead of getting a
neutron captured or you're on your
nucleus a here we can use a deuteron
that I can't make a target out of and
then I should that do to run on my on my
target nucleus and now I can of sneaking
that Neutron into the nucleus and the
proton just slice away so this way I
kind of simulate a neutron capture even
though that's not exactly what I'm doing
so this is a surrogate approach another
approach that it's actually my group
here at MSU in collaboration with the
University of Oslo we are doing
measurements of just measuring basic
nuclear physics properties of the
compound on nucleus that you would
expect from a neutron capture and we use
beta decay to populate this nucleus so
again instead of measuring the neutron
capture directly if I learn enough about
the system I can go and constraint the
neutron capture and we can put pretty
strong constraints on these reactions
with both techniques so as you can see
we're already busy developing techniques
and developing equipment with current
facilities but we're all especially
excited about is with the next next
generation facility which will give us
access to exactly the right isotopes for
our process so facility for rare isotope
beams we've heard already a lot about it
through almost all talks so it's a
project that's funded by the DOE Office
of Science and it's being built here at
Michigan State University the the plan
is for the facility to be completed in
2022 although we're all hoping that it
will be ready even earlier and there's a
large community of users from all over
the world that's already engaged and
getting ready to use this facility for
experiments let me let me show you a
little bit of how I get a cartoon
version of how this facility works how
we can we can do experiments with it so
at the bottom here we start with our
stable beam that's how you start and
that gets accelerated through the
FRIB accelerator to about 200
MBP per nucleon then it hits a target
and it has a fragment where we have a
fragmentation reaction that means it
literally just breaks into pieces and
most of these pieces will be radioactive
and it's this radioactive rare isotopes
that we're looking for now we don't want
to use all the pieces all these
fragments that are coming out we only
want to use one of them the one that we
care about so we use fragment separators
to separate out the isotopes we don't
need and then focus and use the ones
that we do need and we can do
experiments using these isotopes that
are moving very fast or we can also stop
them or slow them down very much and do
experiments like mass measurements and
laser spectroscopy too with these slow
beams and finally we can also
reaccelerating to astrophysical energies
and to experiments with those beams as
well now FRIB is not just created out of
vacuum it's built on 50 years of
experience with rare isotope beams there
is already there with the current
facility the NSCLl National
Superconducting Cyclotron Lab and as you
can see here the NSCL already exists and
it feeds beams into this all of these
experimental areas and whenever it comes
online we will be able to use all the
existing equipment on day one to do
experiments and of course we're
developing new equipment as well so just
to get an idea of some of the equipment
used for our process measurements I'm
showing here just pictures and I'm not
going to explain them individually but
just to get again an idea of all the diversity of equipment we use to do
this kind of measurements to measure
masses or measured beta decay
properties or neutron captures so to
conclude we are really excited about the
theories and the gravitational wave
discovery with the neutron star merger
event because it opens new opportunities
for nuclear science so it will help us
understand all the with nuclear data new
nuclear data we'll be able to understand
better the different contributions of
elements for this blue component and the
red component we talked about already
we're already
running experiments at current
facilities but we're all really excited
to be ready to run experiments at FRIB
either with the existing equipment
that's already available we're also
building new equipment of course that
will be ready for FRIB experiments so
that's it thank you thanks very much Artemis
so if anybody has any more
questions for Artemis or any of the
other speakers you can ask those through
Twitter using our hashtag #gwnuclear or
through email which is gwnuclear@nscl.msu.edu okay so those are all the
talks and so thanks to everybody for the
very nice talks that's sort of giving us
an overview of what was observed and
maybe how to interpret some of those
observations from GW 1708 17 and the
next part of the event is really going
to be a panel discussion that's going to
involve a few other people who we
haven't heard from yet and so before we
get into answering all the questions
that we've gotten during the talks we're
going to give everyone on the panel a
few minutes to sort of give their
perspectives on this event and what it
sort of may mean for nuclear science
going forward what interesting questions
are out there those sorts of things so
the first panelist that we're going to
hear from is Jim Latimer at SUNY Stony
Brook and so among other things Jim is
one of the originators of the idea that
our process nuclear might be synthesized
and material ejected from these mergers
so welcome Jim
okay thank you it's a pleasure to be
here this event has really been very
exciting for me as as you've mentioned
my thesis advisor who's David Schramm
and he had proposed originally this idea
showing a great deal of prescient I
think in this suggestion if I can just
flash off the picture here so as I said
Dave had proposed this idea that we
investigate neutron star neutron star
mergers with the idea to ask to a
looking for the origin of the RF process
and we did some simple calculations but
we used black holes instead of neutron
stars
well we merged black holes with neutron
stars because we thought it was a
simpler problem but we found essentially
the idea that matter would be ejected
and that it would it would probably form
our process nuclei but for many many
years of course this idea was put in the
background compared to the idea that the
real source of the art process was with
supernovae and it's only been in recent
years that the picture has turned around
so this event has really been fantastic
in in showing that this original idea
might might in fact be correct the other
interest I have in this in this event is
the its its impact on determining the
neutron star equation of state and I
think from this there are two aspects
one is determining neutron star radii
and the other is the is determining new
limits on the neutron star maximum mass
and as Jocelyn has mentioned and and
according to the analysis that I've been
working on I think the upper limit to
the neutron star radius is is more or
less around 13 and a half kilometers
from the data that we have and in
addition if one assumes that a black
hole was synthesis was made in this
event which most models showing large
amounts of mass ejection are usually
accompanied by black hole formation also
the appearance the gamma reverse
suggests that a black hole formed fairly
quickly from those from that assumption
you can determine that the upper limit
to the neutron star maximum mass is
around in the range of 2.4 to 2.5 solar
masses which is much better number than
we've had before and there are several
papers also suggested Andrea's Bao swine
is on one of them suggesting that we can
also set lower limits to the maximum
mass brian Metzger is another person
who's been interested in this I set a
lower limit to the maximum mass in the
range of 2.1 to 2.2 solar masses and
that's above the current lower limit
that we have presently so in all this
this event has been very exciting
there's a great deal of impact for
nuclear physics even from the single
event I think we're seeing some major
limits being made and if Jocelyn's right
and we get dozens of events per year
we're really going to be much better off
from determining about the nuclear
equation of state so thank you excellent
thanks Jim so the the next panelist that
I'd like to introduce is Ani opera
he-man from the University of Notre Dame
who's a nuclear experimentalist who's
worked on measuring properties of nuclei
in and near the r-process path so
welcome and we definitely also like to
hear your perspective so thank you Luke
like everyone else in this panel I'm
very excited with this multi messenger
observation particularly excited about
the electromagnetic spectrum of spectra
that's associated with the gravitational
wave measurements as a nuclear physicist
I have been or I should say my research
focus recently had been on measuring
nuclei and measuring nuclear properties
and using the observed abundances of the
heavy elements to try and distinguish
between Astrophysical models for the
site that might be responsible for the
production of the heavy elements now
that we have a definite site perhaps not
the only one but a definite site with
the merger and the Associated signatures
I feel that now we will that gives us a
little more impetus to our measurements
of these very Neutron rich exotic nuclei
particularly because they will give us a
glimpse into what's happening inside the
merger
my theory colleagues here at Notre Dame
have done some work in reverse
engineering nuclear models along with
what is known and they were actually
able to tease out differences between
different neutron star merger
trajectories so I was very excited to
hear from Jocelyn about
the variations or surprises that they
got with this observation and I think it
might just be possible that we can use
the nuclear physics or the properties of
these nuclei to basically tease out the
details of what's happening inside so
that's a very exciting prospect for me
and my collaborators so we've been
measuring some of the very Neutron rich
nuclei at the Canadian penning trap
facility at Argonne and in fact some of
these have been the most Neutron rich
measurements that we can get our hands
on and of course we're also planning on
using FRIB in the near future to
continue some of these measurements it's
exciting that the neutron rich nuclei or
the production of these very exotic
things are very important for nuclear
physics for itself but it might also
here provide some hints a real glimpse
into what's happening inside the merger
so thank you thanks Lana welcome
so our next panelist is andreas Mouse
wine at the Heidelberg Institute for
Theoretical studies and he's worked a
lot on modeling neutron star mergers and
so he's going to also give us some
perspectives about what this means and
what the way for it is so welcome Andy
sorry i muted you so I think what I would like to
point out is that I find it really
amazing how much we already learned from
this one single event I mean how much we
learn for instance about the r-process
from the electromagnetic counterpart but
also what we in particular learned about
the nuclear equation of state that we
can really have already some constraints
on the nuclear equation of state of
course some of these constraints are
maybe let's say a little bit more
tentative others are more quantitative
and more robust and of course it's a
task for the future to somehow order all
these different types of constraints and
to arrive at a consistent picture
of what we actually really know about
the nuclear equation of state but I
think overall we can conclude that we
are really approaching a point where we
get a much much better idea of what is
the actual possible range of the nuclear
equation of state of course most of
these constraints and conclusions in one
way or the other rely on numerical
modeling and it's also clear that to
some extent these models still need to
improve and that there is still a lot of
work to do to solidify the models and
the numbers and we should keep in mind
that in particular when we speak about
the ejecta and the r-process we still
deal with a number of uncertainties from
the hyper dynamical models but overall I
think it's it's reassuring that the
overall picture that the ballpark of of
numbers more or less agree with each
other although they still some work to
do and this brings me to to my
visualised for the nuclear physics
community of to let's say future
research opportunity at least from my
perspective as as a model of mergers I
think what we really need is to get more
equation of state model so I mean in
particular models which contains
temperature dependence and the
composition dependence and my point is
that I think they are actually only a
few models which are compatible with all
constraints that we have at the moment
in particular with these new constraints
from these recent detections I think
they have a much better idea from the
Astrophysical point of view what are the
stellar properties of neutron stars but
we also have some constraints from
nuclear physics for instance about the
symmetry energy and compressibility and
so on and I think it would be really
helpful if we had a larger set of models
which are compatible with all these
constraints and I think what we need are
systematic variations of the equation of
state models to work out systemic
dependencies because we need these
systemic dependencies to interpret
future observations because we should
expect that they actually obtained in
the near future a lot of more a lot of
more observation than we will get much
much more data and and we want to
interpret these data we really rely on
a systematic approach here and so I think this is my wish to do to the nuclear physics
community that we get more equations of
state which are compatible with what we
already know about nuclear physics and
about neutron stars I think this is what
I wanted to say thank you excellent
thanks Andres are in our our final
panelist today is Brian Metzger who's a
theorist at Columbia and he's worked a
lot on predicting the properties of the
ejecta of these events and what sort of
signals you might see from them so I we
also like to hear your perspectives and
welcome Thanks you hear me okay great
yeah I I just want to echo what the
other panelists have said this has been
an exciting few months working on this
event seeing the implications being
played out some successes some mysteries
I think by and large you know it's
mostly I mean it's it's it's been a
combination of successes but also
realizing sort of you know in the future
what we're going to need to turn these
into more precise probes of the nuclear
physics so for instance I think the fact
that there was this r-process nuclei a
few percent of the sun's mass produced
is very robust and I think the fact that
you know theorists were able to make
these predictions for the radioactive
heating and the kilonova emission and
then to have it seen just really puts a
lot more confidence in that discovery I
so I think this really illustrates you
know the power and importance of theory
of bringing together you know
astrophysics and nuclear physics and so
this is you know really at the interface
of what we need to be continuing to do
as Dan discussed you know the color is
amazing thing is that the colors of the
kilonova which are related to atomic
physics you know whether their emission
is blue or red is imprinting key
information about the nuclear
composition in the sense of you know
whether or not we get past the second
r-process peak whether we have matter
that it's you know free or rich in
lanthanide and actinide elements and so
that's i think the really exciting thing
is that when we see you know something
that's that's blue becoming red or
something that's that's purple or
whatever you want to say in between
how we see this from different angles we
really sort of you know taking an x-ray
in some ways of this of this merger
really learning a lot of the details um
you know but I think it is you know
important that you know for our ability
to take a simulation of the merger what
is produced and to translate it into
what we see there is this crucial step
where the nuclear physics comes in
particularly you know some of the
nuclear properties near these these
close shells which are really
determining how far the nuclear flow
goes and on what timescale and so I
think there's definitely a key role for
facilities like F rib to really you know
improve our ability to make this mapping
I don't know if this was mentioned
earlier but you know I think I'm pretty
convinced that the dominant source of
you know the ejecta within these mergers
came from the accretion disk that formed
around the black hole afterwards a very
large part of the matter that's at least
my opinion so it's very humbling to
think that you know the the platinum and
my wedding band was within a few short
shield radii if a black hole and could
as well just been sucked in as well as
ejected into space so as Jim discussed
I think the other beyond the r-process
side of things I'm very excited about
the implications for the equation of
state I think Andy's exactly right who
would have thought we'd have you know
from the single event all of these
different constraints coming in in terms
of the upper limits on the radius from
the title deformability the the lower
limits on the radius from the fact that
when these two neutron stars merged the
object didn't immediately collapse into
a black hole we're pretty sure of that
so you know that tells us neutron stars
can't be too compact you know it's even
possible if the you know equation of
state can support a very massive neutron
star that when these two things merged
the object wouldn't want to collapse
into a black hole it would produce some
very rapidly spinning highly magnetized
neutron star and we don't see any
evidence for that in the data and so
this can begin to constrain the the
maximum mass of the neutron star quite
tightly so I think a lot of these
constraints you'll see from astrophysics
there's you know especially these things
that are multi messenger where we're
combining gravitational waves which
measure the total mass of the binary
and then we see something
electromagnetically which tells us about
the remnant they come with systematic
uncertainties a lot of astrophysics
does but that's you know but that's why
it's exciting we're gonna have more of
these because we can test some of the
ideas we can say if this is the right
explanation then you know then why
should happen next when we see a merger
from a different angle or if we see a
merger with a higher mass it should do
this and so I think we're going to sort
of learn as we go along whether these
assumptions we're making are correct and
and it will be fascinating to me if some
of the constraints were getting from
from these events disagree with those
that we infer from laboratory
experiments for instance like you know
Neutron skin thickness of lead or
something if that gives a radius which
doesn't agree with what we're inferring
from gravitational waves then you know
what does that imply about the equation
of state you know are we seeing some
evidence for not saying this would in
particular but are we seeing evidence
for you know exotic phase transitions
that happen in the centres these objects
before or after they emerge so I think
that's the main you know takeaway I want
to say is that you know it's it's gonna
be very exciting as we go ahead to see
many of these events but but see slight
differences between them and how you
know how qualitatively different the
signals are as we vary that the
properties of the neutron stars going in
will be very fascinating so I'll finish
there excellent thanks Brian thanks
everybody
okay so during the talks and everything
we've gotten quite a number of questions
both from Twitter and via email and I
think via YouTube I failed to mention
that but people are watching this on
youtube I think you can ask questions
there as well so the first question we
got comes from Stan Woosley in Santa
Cruz so this is kind of an interesting
question that people have maybe haven't
touched on so much before but is is
whether or not merging neutron stars
really can make up all of the r-process
that we see in our galaxy so Stan asks
we see that merging neutron stars make
elements attributed the art process
possibly in sufficient amounts to
explain what we see in the Sun but what
can we say about the synthesis of
different components just like s process
the r-process has to be built up from
a distribution of exposures in his words
is there a need for room for
from other sources in the r-process so
something like supernovae to be
responsible for maybe the light r-process say less than a of 100 I don't
know maybe either Brian do you have well
I mean I can say just in terms of this
event we I think we're seeing evidence
for different Neutron exposures you know
we're seeing some evidence for a very
lanthanide free matter which clearly
didn't have enough neutrons to get much
you know past the second peak and an
evidence for a smaller fraction that
likely did and so you know I guess
that's a distinct question from whether
the very lightest star process elements
come from mergers unfortunate aspect of
the kiln of it is it does tell us you
know sort of this dichotomy lanthanides
or no lay of the Knights but I think we
need you know to do additional work to
to really tease out you know the detail
quantities of different you know
isotopes I think that's you know still a
little bit still a little ways off but
you know my opinion is there you know
currently there is still room I think
for the lighter our process elements but
definitely in this event we're seeing a
wide likely a wide range of neutron
exposures and probably a very wide mass
distribution being synthesized but
feathers should come in as well
yeah I I could say that I'm the from the
amount of mass ejected if it's really
one twentieth of a solar mass and most
of that goes into our process elements
and given the estimates that LIGO his
LIGO collaboration is made about the
rates even though there's a factor of 10
uncertainty in that rate the product of
those two numbers gives more than enough
our process matter if the Sun is a
typical you know has typical our process
abundances
but maybe it's a little bit too soon to
exclude any other contribution I mean I
think there's some debate going on
exactly how many what the mass fraction
of the lanthanides were in this event
and exactly how neutron-rich it was so a
yeah I think it's I agree I think we in
principle it seems like we have enough
you know at face value but it would be
good to see a few more events and and
and this isn't what we see doesn't
really tell us anything about the
lighter nuclei yeah so another question
that we have from Mikael in Scotland in
this is maybe best a question from Mansi
is do you have any information about
high-energy photons produced during this
merger say 100 MeV to 1GeV to 10GeV why
what is the highest photon energy we
succeeded in detecting associated with
GW170817 sunset was seen sorry can
you hear me yeah I just I just unmuted
you sorry ok so the hardest photons that
were seen were by the Fermi and integral
satellites so these were the gamma ray
photons and the new star satellite still
hasn't detected anything so they're not
hard x-rays but suddenly gamma-ray
photon flux was detected
okay and what was what were the hardest
gamma rays detected you know it's
probably around and I mean I'm guessing
a few hundred kV or something I don't
think there were too many MeV photons
but you know we're not talking GeV or
hundreds of GB okay we also got some
questions a number of questions from
Indiana so I see where is this question
so one thing I think a lot of people a
lot of people have asked about and Chuck
Horowitz a person in particular was
asked about this is that there's this
delay between the gravitational way or
the gravitational waves and
electromagnetic signals so how should we
think about this 1.7 second
delay between the merger and the
gamma-ray bursts so what could be
responsible for this time delay what
sets what might set the delay timescale
what are ideas that are out there for
this can I could I answer this okay I
mean I think I think broadly speaking
there's sort of four possibilities maybe
interest increasing interest or excited
or probably also decreasing likelihood
but I don't put him in that order I
think you know one possibility is that
there was a delay between the merger and
when the gamma-ray bursts jet was
produced so this could because this
could be because it took 1.7 seconds
roughly for the black hole to form and
make it jet it could be that a black
hole formed but it took a long time for
the magnetic field or whatever's
powering the jet to be produced it could
be that there was a jet produced but if
there was a giant cloud of material
which probably man see discussed that
the jet had to escape from and it took a
significant amount of time to escape it
could be that the emission sight was
very far away from the from the merger
so that the time it took for the light
to get from that point to us was was you
know there's this additional time delay
to get to us from when the gravitational
waves did so that would be like a light
you know time travel effect local to the
source and then the final one I guess
would be that there's some exotic
physics that's causing gravitational
waves to travel you know faster or yeah
faster than then electromagnetic light
so anyways but in terms of which is the
most plausible I think it's still up for
debate but I've been increasingly
hearing it the case that a lot of people
believe you you do need the jet to be
delayed somewhat from when the merger
happened so what we fascinating is if
that if that was telling us that it took
a second for the neutron star to
collapse into a black hole that's sort
of an unnatural timescale we think that
what causes the collapses is the removal
of differential rotation from the
merged object which
what's supporting it centrifugally
against gravity
in most simulations I've seen suggests
that should happen quickly within
milliseconds they're tens of
milliseconds not you know thousands of
milliseconds so I think it's
still an open question but a very good
one actually anyone else have any
thoughts on what this the implications of
this delay might be how about you Luke
I don't have any idea I essentially I agree with you right that this delay is way too
long to be explained by you know a
lifetime I mean maybe you could have
some proto neutron star living for
that period of time that's probably
probably too long a question another
question that's actually pretty closely
related maybe to this delay timescale if
it has something to do with interaction
with material around it is also for Mansi I'll take you off mute this time
ahead of time and so Milton Murray's at
UIUC asked if the observe low luminosity
short gamma-ray burst is due to a
circumbinary cocoon rather than an
off-axis relativistic jet is the total
electromagnetic luminosity emitted from
binary neutron star merger comparable to
a typical short gr B is it do you have a
sense of that
so if you look at the volumetric
luminosity I turn the paper that's
actually only a couple times and the 41
of the second so you know own axis
shorter gamma-ray bursts you see the
afterglow component which is much much
more luminous for a much shorter time in
this case the bolometric luminosity
evolves on on several dates a few weeks
time scales and and it's overall it's
lower than than what you would expect if
you had this not relativistic jet that
we were based on looking down the barrel
of the jet and seeing an afterglow
component so so it's somewhat under
luminous from what you'd expect from a
regular short gamma-ray burst okay
interesting and he had a second
a second part of this but do you think
you more or less answered this which is
the luminosity observed when integrated
over all am wavelengths I think that you
answered that or is there how much of
this energy might be converted into
kinetic energy in the outflow is that a
significant energy loss I think that's
the case for kilonova right is that
right and in fact I mean the the kinetic
at kinematics are very interesting
because the kinematics here could
suggest that some of the ejecta is
moving so fast that the assumption that
you use newtonian velocities and all of
these kilonova simulations may not be
quite right and so you might might need
to actually take into account
relativistic effects of these velocities
and that can again explain this bright
blue early emission that we see if
material is in fact accelerated to fit
against the speed of light
Thanks so we also got a number of
questions about the title deformability
of these neutron stars related Jocelyn's
talk and so like Jocelyn can help answer
some of these and I'm sure I'm sure Jim
and other people will also have have
some thoughts so Fertoya at Indiana University I
just wanted to know if Jocelyn can
elaborate more on the sudden change in
the lambda 1 lambda to 90% confidence
contour plot in the upper top corner
does this have any implications neutron
star mass as a radii and and also Chuck
Horowitz who's also at Indiana also
asked about how much is the lambda
equals zero deformability disfavored by
data is it a disfavored at all or just
that you have this upper limit yeah oh
really sure what the top corner yeah so
I just have the question that he asked
so it just says that there's a large
lambda one in a small lambda 2 section
in the upper top corner
so is that so I mean so one of the
things we see is with the wide range in
in mass ratios the deform abilities can
skew to have a very compact more massive
star in a very deformable low mass star
that would be compatible with the masses
although not so much with our recovered
tidal deform abilities we we do so you
can see in the distribution that the the
most favored values are a little pulled
away from the lambda equals zero lambda
equals zero sort of binary black hole
equivalent corner although that is more
sensitive to wave form systematics that
are still under exploration so you know
it's not it's not a distinction from the
binary black hole case that that we can
make at say the 50% level even at this
point there's some hope with some of the
ongoing reanalysis with improved wave
form models we might be able to say more
but it may just be that you know with
more compact neutron stars they're more
challenging to distinguish precisely
from black holes and so especially with
the current sensitivity of the detector
has increased noise fluctuations at the
high frequency where the merger happens
so for this signal that that may remain
masked by by the noise one thing one
thing is a couple of people mentioned
earlier this very worth saying
explicitly is the the error on the wave
forms is a big source of errors for us
right now but measuring these nuclear
effects you know the the vacuum wave
forms can be calculated it's very very
precisely but obviously when you throw
in the nuclear physics into binary
neutron star mergers things get much
less accurate and to the level of the
the effects we're trying to measure
right now or of the order of errors and
the numerical simulations and so a lot
of work is also going to be needed we
can improve with the models we have
better models than we want the ones we
used in the paper but they're still not
perfect so it needs to be a lot of work
on improving that you
the models of the Bayou chose colleges
so so for this question about the the
large lambda 1 small lambda 2 in in sort
of the upper corners of the plot right
where I guess you have the largest mass
ratios maybe or those that what you're
showing there is not really constrained
by any equation state model right it's
just coming purely from which you get
from the Inspiral data is that is that
right right so that the yes so we do see
really the constraint we make on the
title deformabilities is not so much
on the component title deformabilities but on some combination of
them and so there's a sort of a
degeneracy in the gravitational wave
signal between say an equal mass system
with some moderate title deformability
on each star and a more unequal mass
system where one of the stars as as the
star gets more massive it becomes
much less to formable typically the
radius may decrease but the the mass
also has an effect on this and
conversely a low mass star has a much
larger title deformability in terms of
how how it feeds into the gravitational
wave signal signal so we can't really
tell with this signal whether we had
sort of two moderate stars or one compact
and one large star but even those those
large mass ratios would be consistent
with you know predicted nuclear
equations of state or is that oh so I
mean yeah so at some at some point you
know if you've put in assumptions about
the equation of state generating the
stars those come in with maximum mass
assumptions and those right now that's
not in our analysis we allow the masses
and the titles deformabilities to
vary entirely independently freely over
the range but you know to to fully kind
of make a consistent picture of what
we're saying about a neutron star
equation of state describing both
stars that to do that properly requires
you know the the the equation of state
assumed has implications on the allowed
masses and that can become a little more
complicated in the analysis if I could
comment where I think that quote-unquote
realistic equations of state don't
predict much of a radius variation for
stars in the range between 1.2 and 1.6
or 1.5 where these two stars are likely
to be so in that sense the tidal deform
abilities will depend mostly on the
masses rather than on the specific radii
the radii will be set generically by the
equation of state and won't vary by more
than a few tenths of a kilometer for
stars in that mass range so I think to
infer that that that the information is
such that the that two different vastly
different lambdas implying two vastly
different radii stars is is simply not a
realistic extrapolation yeah that's
that's a good point the the lambda
parameter it depends on the combination
of the mass the radius and the and the
love number so that that combination is
not necessarily suggesting for example
that you know the radius difference is
proportional to the lambda or the title
deformability difference okay excellent
thank you
so another question that we had going
back a little bit to kilanova stuff
and maybe either Dan or Mansi you want
to answer this one I think
Mansi was a person who said this is
that someone had asked why is it a
surprise that the electromagnetic signal
is the optical electromagnetic signal
was bright and blue so what was the what
was the surprise there well I could say
I wouldn't say it was a total surprise
that it was that was blue at early times
I mean that was part of the theoretical
picture that we had prior to it that you
would likely based on simulations have
these different components of ejecta
some some parts that
or less neutron-rich and made little
pasady blue optical emission and others
that made longer-lasting red emission
from heavier elements so I think that to
the component picture was was there and
there were models done that showed you
know some blue emission that was you
know maybe a factor of a few dimmer than
what was being so but you know whether
you had that blue emission or not
depended upon certain conditions in the
in the merger whether you whether you
really could produce those element
species which depended upon details that
we didn't know so it could have been
that there was no blue emission but
there could have been some significant
amount and the amount we saw was
actually at the very high end of what we
had expected and so we were lucky in
that regard and the mass is inferred of
that blue component of you know few
hundreds of a solar mass are you know
there on the high end a factor of a
couple compared to simulations which
typically get up to a percent or so so I
think within that uncertainties that we
have it's it's consistent but but you
know we were lucky to be on the high end
of that that blue component rather than
the absence of it because it would have
been a lot harder to find optical and I
just like to add that the first
ultraviolet observation was 14 hours
after merger and it was seventeenth bank
and you know while the work models had
predicted some blue emission most of the
the models are predicted by permission
was it in on the few hour time scale so
I'm not half a day more than half a day
later and the luminosity was just so
high that you know I think you can
always crank up some parameters and mass
and velocity and no past and lower the
opacity to try to to make this work but
it does require pushing to you know
uncomfortably a little bit higher than
than what existed in predictions and I
think we should be open to different
ideas and what the what the
only by the emissions and I think one of
the biggest open questions and future
events is what does that blue emission
during the first 12 hours does it just
fall like a rock or is there a finite
rise and then a decline and that can
distinguish between the various ideas
out there on what could give such pride
to a mission for a sustained period of
time thanks yeah so we're the maybe
maybe a related question I get a
question I sort of had that relates to a
question that someone asked is so Sam
Austin here at Michigan State University
is just acting asking how many kilonova have been observed for instance
one obvious case is maybe GRB 1306 o3b
the afterglow there so so would you have
expected this if the blue component
there look the same as it looked in GW
1708 17 would you expect it to have
observe that in this maybe this other
instance of the kilonova that we have
Bryan looks like you might have
some thoughts I'm sure of Nancy does too 
so everyone can fight Bryan just a second well okay
I mean I think Nancy can address
better whether or not we would have seen
these in previous surveys my
understanding is it's hard because even
though they're bright they're they're
rare and they're fast evolving and we
until recently haven't had many surveys
that could see these but but I'll let
her answer that I do want to push back a
little bit I will say that you know I
think our even back in our 2010 models
you know fit to this event we can
actually get something very similar to
the blue omission that was observed now
of course we were assuming things like
very high thermal is a ssin efficiencies
but I would say that that you know the
idea that these bluer models were in
places I would I would say not entirely
correct
but I would also say pushing what she
also said about the early you know
emission on a few hours I agree that
scale is you know if we can get on the
next one this one happened over the
Indian Ocean so everyone had to wait for
11 hours for you know to rotate so
people could observe in Chile we have one
over North America that we can view with
Palomar mansi can view we may be able to
get on very early and that would be very
exciting because there were probing the
very outer layers of this material
whether you know one thing that can
happen is if
the matter expands very fast you can
actually get a freeze out of the r-process which leaves a bunch of free
neutrons in the outer layers and those
neutrons have a fairly long half-life
compared to the typical r-process
nuclei so they dump in a lot of energy
on a time scale of a few hours and
that's actually would be really
interesting to probe because it actually
would be sensitive I think to the
conditions in the ejecta and some of the
nuclear properties near the waiting
points which control whether the r-process might freeze out and but it
could also be that this cocoon emission
contributes there so if we see it you
know this hot shocked material is the
jet breaks out of the material out of
the ejecta the so I think I think yeah
that for those first few hours there's a
lot of key information and it would be
great if we could get on earlier that's
all and if I may add about the short
hard gamma-ray bursts that previously
have means you have kilonova
components there are five such creams
out there and if you assume that GW170817 is now the new truth function and
what a nexus emission was you know these
five previous claims were sort of
fraught with one data point being an
excess of what you expect from an
afterglow and potentially coming from a
kilonova and if it's just over plot
what that one data point based claim was
then GRB160821b and GOB050709
fall exactly on top of the
light curves of GW170817 GRB130603b
look the one that you mentioned the
most famous as far as media goes on this
is actually a little bit higher but half
magnitude higher than iam 1717 so it
still requires pushing the jetta masses
even higher to explain in this context
and the two others don't land and are
not consistent with this thanks that's a
great answer
we've just just doing something on the
on the timing given that people mention
this there's in principle no reason why
why LIGO/Virgo can get
alerts out in a few minutes this was a
both lucky and unlucky
that we have this this type of known
class of glitch landing on top of it
that took some manual processing we
actually already had software that
automatically removes those glitches
from from the analysis but we turned it
off in the low latency search for
something loud a short loud signal so we
already have tools in place to take care
of that so we should be able to get
these out in inorder minutes and future
and in O 3 thanks so well while we're
still talking about the kilonova stuff
we'll switch it over a little bit to
some questions people had about nuclear
physics input for the models and things
of that nature
but one last question I think it's
important to answer this I think is that
so someone that asked what what elements
were actually directly identified in the
spectra they thought that some
particular heavy elements were created
and we're seeing and is there any
evidence that other heavy elements were
created there so I think you know
mentioning that maybe we don't you know
see direct signatures of any particular
element might be useful to say and what
signatures we have so Dan or dance
felony of the person to talk about this
yeah it's hard to say because as I
mentioned the you know you see some
features to the infrared spectrum the
optical is basically featureless and
it's large because there's a lot of
lines involved and they all get blended
out and some features that are kind of
composite features now as once you guys
showed you know some of the models that
we had done kind of fit the locations of
those Peaks fairly well and the dominant
element that was producing those Peaks
was was neodymium which is one of the
well first of all it's a it has an
atomic structure since it's a lanthanide
that's quite complex so it naturally has
a very important effect on the opacities
emission and I love the lanthanides it's
one that's made in large abundance we
think in r-process so that may be one
of the key players in shaping that
spectral behavior but it's hard to say
that these early days I mean we don't
great atomic data in line lists for all
the many elements across the periodic
table that can contribute and and they
contribute in a non-trivial way as they
blend together so we we showed as a
proof of principle as we vary the
abundances in the objective we changed
the amount of neodymium by some factor
increased the amount of some other
element like cerium
it changed the locations of peaks in the
spectra and so I think over time as we
understand the the nuclear physics and
eating better and we understand the
atomic physics of the lines better we
can we can dig into that and in say in
some more detailed way what elements are
contributing but at this point there's
some hints of neodymium playing a role
with with some uncertainty and I think
other other attempts at line
identification are not very reliable
thanks Ted so now there are actually a
bunch of questions about sort of what
sort of nuclear physics input might be
sort of the most important things to put
it especially the simulations and you
know how we interpret these events so
maybe andreas is a person to answer this
one you already touched on it a little
bit but maybe it'll open more detail
it's just just what what nuclear physics
input is needed for neutron star merger
simulations and in maybe what's the most
important input what should we what
should the nuclear physics community be
going after to really constrain what's
happening in the central engine of these
things better I I think the I mean the
dynamics of the merger and the
gravitational wave signal and the
dynamics of the mass ejection of course
all determined by the equation of states
or the equation of state is the is the
is the key tool to all these observables
and so I think the the most important
property of the equation of state
determining the dynamics is probably the
pressure as a function of the of the
density so essentially you could also
translate it into the radius of of
neutron star and so this relates
essentially to the slope of the symmetry
energy if you want to hear some nuclear
physics parameter that is the most
relevant maybe for the equation of state
or for the properties of the equation of
state so I think this is what it's
probably the most important that is
determining the the the overall dynamics
and so and so which which nuclear
physics input is likely to be the most
important is it like you mentioned
measuring the symmetry energy the
density dependence of symmetry energy or
is it something you know as a low
density nuclear equation of state that
matters or what's happening a very high
density near the neutron star core III
think measuring the slope of the
symmetry energy would be extremely
helpful and everything else that you
could measure above saturation density
would be of course also very helpful if
this is possible but you know fixing the
pressure at a given density would be
already very very helpful to which
extent the low density part really
effects for instance the gravitational
wave signal is probably questionable
because you know the the bulk Mass
Effect's the gravitational wave signal
and it also affects the overall dynamics
and therefore the mass ejection so I
think what is going on at at higher
densities is the most relevant here for
further gravitational waves politic
gravitational wave signals but also for
the mass ejection because the mass
ejection is somehow triggered by the
dynamics of the of the total system its
composition you're gonna have to go
through low density material to
eventually to get out so I mean so
getting getting stronger constraints on
the the equation of state is one aspect
we also I mean this so you know I think
we'd also like to think about you know
what what sort of measurements are the
next things that we can do to constrain
that you know I know that we didn't talk
too much about like heavy ion collisions
and those sorts of experimental
measurements but I don't know
we must want a comment just a little bit
on what the sort of the prospects are
for you know getting some constraints on
the nuclear equation of state from
trusts real laboratories yes look if I
could just say something
I appreciate Andres's point about the
equation of state that that's kind of an
overall effect but if you look for an
r-process with the individual nuclear
properties like masses Neutron capture
rates beta decay rates and beta delayed
Neutron emission probabilities out of
those we have shown in lots of
sensitivity studies that the masses play
the biggest role they have sort of the
biggest impact on what is produced and
Dan case and also showed some plots with
different mass models depending on where
which of the r-process Peaks get
populated depending on what limits are
used so in a way nuclear masses are the
most important thing right away they
have a bigger effect if I could comment
go ahead Jim so I think that we're saying the
same thing I think that nuclear mass is
extrapolated to Neutron very Neutron
rich nuclei depends very sensitively on
the density dependence of the symmetry
energy and that's precisely what
controls the radii and the tidal deform
abilities of neutron stars which are the
most immediate things that are measured
from these gravity wave events and I
should also mention that there are
upcoming Astrophysical studies that can
also bear on this but you know we're
focused more here on nuclear studies and
so the the next generation of the prex
experiment for example could be very
very influential here as well in getting
enough a systematic free if we could
determination of the neutron skin
thickness which is very closely
correlated to both these properties
neutron star radii and the symmetry
energy density dependence thanks to and
maybe if I can add as well that the in
terms of measure
for the equation of state I'm not an
expert but I know already people are
doing experiments where they're trying
to use symmetric matters so equal
numbers of protons and neutrons and then
use nuclei they're both very asymmetric
very Neutron rich and then two
comparisons to heavy iron collisions and
do comparisons and so then with the the
next generation facilities and with
FRIB because we can go even more
neutron rich we can probe even larger
asymmetry now that'll hopefully get that
some constraint on symmetry energy had
adding around saturation density right
is another question that relates to sort
of some nuclear physics uncertainties
and Dan touched on this a little bit in
his talk but this this also comes from
Chuck Chuck is asking many questions
today as usual so it's how does how do
nuclear physics uncertainties impact
heating in our heating in these Killa
Nova and the ejecta masses and then
maybe a follow-on to that you know what
could we go out and measure that would
help better constrain what our heating
efficiencies in the Killa Nova ejecta
and things like that so I'm sure that
many people on the panel who might have
something to say about this so whoever
wants to go first can jump in I could
say that that's one of the key
uncertainties because the different
nuclear mass models you know for the for
the same initial conditions will produce
different abundances of elements and
different than radioactive heating rates
and the differences can be factors of
several four or five and the later times
in particular in orders of magnitude or
such and so that directly goes into our
estimates of how much mass is ejected we
need to know quite well with the what
the nuclear heating rates are and one
handle we may have on it is is
observationally to probe it is to look
at the late time observations of kilonova because it's there where you
tend to see the biggest differences
between the nuclear mass models and the
heating rate models that would predict
heavier translated elements that produce
more
alpha k thermalize more effectively at
late times and produce a brighter kilonova so there's some interplay there between learning more
about the nuclear physics and comparing
it to a long baseline kilonova
observations thanks Dan
ani you had a comment you're off meeting
now sorry I was just going to I was just
going to ask Dan actually specifically
what the heating is resulting from
directly which nuclear property
contributes the most besides the entire
mass of the ejecta is it what is what
nuclear property determines that you
what's the nuclear decay pathways that
are controlling this is it just a decay
yeah I mean primarily it's it's it's
beta decay of these Neutron rich nuclei
back to stability so those are producing
gamma rays and fast electrons the gamma
rays will after a few days or so they
typically can escape the ejecta and say
they're no longer efficiently heating
but the the electrons the betas will be
trapped longer and will be able to heat
more efficiently at longer timescales
and then for the heavier nuclei they can
also undergo alpha decay or maybe
spontaneous fission at late times and
that those those products the alpha
decay products will probably thermalize
more efficiently and so that's one of
the distinctions between different mass
models is you know how much alpha decay
you get from your particular nuclear
model at late time once the beta start
escaping effectively yeah some of the
work that we did showed that it's not so
much dependent on which nuclear masses
you use but the astrophysics
trajectories for a murderer versus a
core collapse supernova
different enough that they emphasize
different nuclear different beta decay
rates so I think that if we're able to
measure those beta decay rates to high
precision we'll be able to say something
about that the heating aspect - yeah
that would be fantastic to better
understand that heating as you go to
later times things are decaying
back down to stability so they're not as
far away from stability originally was
the path itself will set what isotopes
they're the beginning to decay tap yeah
if I can ask a question to go for so
that's it does it matter how the energy
gets distributed between the gamma rays
and the electrons and the neutrinos in
this process yeah very much so the neutrinos are just
gonna escape immediately the gamma rays
may be trapped for the first day or a
couple days but then they escape and
then the electrons are more effectively
thermalized so you know how bright the
kilonova is is is a function of how
much energy is coming out in those
different channels how much function how
much energy gets thermalized and so if
we change those if we figure out that
those are different than our kind of
default assumptions now that changes how
our estimate of what the kill in the
list how bright it should be and what
the mass involved is which is just that
you know when we have very Neutron rich
matter which boots up to the heaviest
elements and we maybe get fission
cycling all these things weekly ten even
without fidget cycling we tend to get a
radioactive decay you know in terms of
which is which is you know some kind of
peril or it's usually a statistical
combination of many nuclei but if we
have less Neutron rich matter like in
this event where we see that there's
some matter that didn't produce such a
wide distribution of nuclei
what you find and Luke and comment as
well is the heating is sometimes
dominated by actually a few a few nuclei
or you see you you see more bumps and
Wiggles and so in that case I think the
higher if you go to higher ye less
neutron which matter I'm guessing the
heating rates that we infer become more
sensitive to some of the individual
decay times of these nuclei and I don't
know if this would be possible but if we
at some point saw something that looked
like an exponential decay and the light
curve of some nucleus you know being
able to match that half-life to
something we measured in the laboratory
would be good because it's a bit ways
off I think but you know it's something
to think about so maybe Luke wants to
say something more no I think you said
most of it I'm just that just the
moderator not supposed to comment to much okay so I think I think we
are probably pretty close to wrapping
it up one last question that was that
was pretty interesting that we got for
the sort of nuclear experimentalist and
this sort of feeds back on what we were
just talking about now what are the
implications of this event for you I
mean what sort of different measurements
are you thinking of going after that you
were maybe previously not thinking of
going after but you know do you think
this opens up sort of new directions
that you want to go into I already
messed I guess you can start yeah sure
so I I mentioned earlier that before
there would be sensitivity studies on
all different varieties of Astrophysical
scenarios and so then each of them would
predict different nuclei being important
and then from our point of view we would
basically have to measure everything so
it's important that now we know which
nuclei we should be targeting the other
thing is that since this is a colder
very Neutron rich scenario we know that
it goes much further from from the
stable isotopes it's maybe even all the
way close to the drip line to the
neutron drip line so we know that we
really have to reach to those most
neutron rich isotopes and that's what
where we're getting with FRIB which is
which is great and then the last one
that I kind of briefly mentioned in the
talk is that if we're not in a new n
gamma gamma in equilibrium that means
now that the neutron captures matter
which was not so much the case if you
are in the Caribbean thanks
so I I think we'll sort of maybe maybe
wrap up here because we're getting quite
quite close to three and so sort of is
just a final thing I think everyone on
the panel we just want I just want to
hear for everyone on the panel sort of
what's the most exciting opportunity
going forward from GW 1708 17 so I just
just give us sort of a brief answer what
you think is maybe the most you know the
most interesting new research direction
maybe the a most interesting puzzle
that's been left behind or what's sort
of going forward so maybe we can start
with Duncan on this I think I think the
most exciting thing here is is the fact
that we are going to be detecting a lot
of binary neutron stars moving forwards
and we're just going to get more and
more of them as like a riches design
sensitivity being we were this signal
that have been more favorably oriented
would actually be undetectable by initial
LIGO which is which is somewhat
remarkable and there seems to be this
gap between the GRBs that
have redshifts and GRB170817 there are
fainter GRBs that have always been
assigned to being a large redshift but
maps are actually much closer than
previously been thought and so we might
actually be seeing quite a few of these
these joint observations much more
quickly which will provide a lot more
data in the years coming forwards I
think that's for me that's not server
that's on the most exciting things go
forwards excellent thanks Monty what are
you too many things given that the
future seems to be quite literally
bright and loud so one of the things I'm
very curious about is what a neutrons a
black hole merger would look like so the
Duncan you guys have some work to do to
find that one soon and of course I mean
this question of you know there's so
many models earlier data would be even
better in the first few hours the cocoon
models really correct and you know I
mean I think larger samples would put
tell us the sound so under this is just
the beginning it's really exciting
excellent thanks
Brian you're on mute
yeah I mean I think for me you know one
of the exciting things that I sort of
realize you know is you know there's
this interesting coincidence in this
event between the delay until the
gamma-ray burst and which is a few
seconds and actually the time it takes
for the r-process to complete and so
now that we're starting to talk about
jets breaking out of giant cocoons one
of the things I'm seriously thinking
about is is is the r-process we used
to think of it just sort of this
ejection of material in a few
milliseconds it expands into space the
r-process happens in a way that's sort
of independent from what's going on at
the central engine I'm now beginning to
think well maybe maybe it's not so so
simple maybe there's interplay between
these different components maybe the
matter is a shock heated again as it's
going out and this can produce a more
complex thermodynamic history for the
r-process material that that's
produces so to me that's the fascinating
thing is this sort of we're getting this
evidence as Mansi said that from the
second possibility that that you know
there may be interplay more complicated
thermodynamics going on than we
originally thought so excellent thank
you Brian
so Jocelyn what are what are your
thoughts on what's maybe most exciting
going forward yeah so I mean of course
the prospect that this is going to be a
common occurrence in a few years is
really delightful but I think you know I
think one one thing that that I think is
fascinating right now is just trying to
best figure out how we can feed in all
the information we have about the
properties of neutron stars we see the
numerical simulations the best guesses
for how it's possible that the neutron
star equation of state might behave and
see if if we can do a better job even of
analyzing this first neutron star merger
going forward I think the story's not
over yet for understanding this one
signal so I'm really looking forward to
creative ideas for
how to best interpret what the data is
telling us cool great uh Jim what are
your final thoughts here yeah I course
was so excited by this event that I
could hardly imagine what might happen
if we see a neutron star black hole
merger and I I think my feeling is that
the predictive power that computational
astrophysics has been able to achieve
has just been fantastic and really
justifies moving forward in this
direction and and so I anticipate that
these next observations are going to
help us constrain things even further
others it's remarkable how single event
has really changed change things so
thanks uh Dan what's your sort of final
thoughts here
yeah lots to be excited about I think in
particular we have this you know after
years I was trying to tease out where
our process was by looking at its trace
abundances and stars and you're right so
we have now this pure sample of our
process right at its production site and
we can we can try to analyze that and
was one thing that was surprising about
this event the killin opah was that it
was not all that surprising in its
behavior it the you know the first order
kind of matched the the predictions of
what we thought it might look like but
but who knows is the diversity events
and we get more kind of mergers will
they behave so well or well they throw
some surprises at us in any case there's
a program going forward to try to see
what range of behaviors we get and try
to probe the heavy element production in
more detail excellent thanks Dan ah Andy
what are your final thoughts here so I
think I care my excitement with them
that I would really like to see many
more neutron star mergers and to
understand the diversity of these events
and and really to compare different
events to see how much they differ and
what
tells us actually I think this this
would be something very exciting and
then to join different constraints on
Mars ejection and the equation of state
and another prospect that I find very
exciting is that I mean this was a
relatively closed event and as we
approach design sensitivity we might
have the chance to detect all the
post-merger gravitational wave emission
which could tell us something about the
fate of this merger realm and if it
collapse directly or whether produced a
hyper mass of neutron star or maybe even a
supermassive even so this could tell us
a lot about the dynamics going on in
this data and these are very exciting
for the future they definitely super
excited so arduous what are your sort of
what do you think the most exciting
opportunities going forward from this
are well I'm really excited to to use
now nuclear physics current data that we
have already but also future data with
FRIB to try and interpret the
observation it's been better and and I'm
learning all the time even now with with
a discussion about heat that there's
even more nuclear physics that we need
to be looking at so I'm really excited
to go and attack these problems like
some things and then the last word here
yes I think this observation has made it
even more important to eat that we go
out and measure the most neutron rich
nuclei because we've already at least
identified a set of nuclei that would be
more important for neutron star mergers
than for other types of r-process
scenarios so for me it would be really
exciting if we could measure those and
then be able to duplicate the light
curves that so many people are observing
and if it's true that we're gonna see
about 40 a year I think there there's a
lot of excitement but the merger nuclei
that neutron rich nuclei are a lot more
Neutron rich than some of the other
things we've set our eyes on so the
challenge is open and
it's really exciting for us to go there
awesome thank you and thank thank you to
everybody both the speakers and bullit
and all of our panel all
the director of JINAwho also organized most of
this and made this event happen and I
also want to thank everybody who sent in
questions via Twitter or email sorry
that we didn't get to get to all the
questions that came up there are a lot
of good questions and if people want to
answer other people's questions on
Twitter that would be great so hopefully
everyone enjoyed this event and thanks
for what tuning in and watching
