When you think about astronomy, virtually
everything you've ever heard, everything
you know, is astronomy that's been
learned with a telescope. All of us have
grown up in a world that sees the
universe through the eyes of Hubble, but
there's a lot about the stories that you
can't just learn from the light. And the
thing that's so exciting about this
event, is that it's something we've
always known,
we've always predicted, that if you had
light and gravity together, the two
pieces of information could tell you
something more. LIGO had its first
gravitational wave detection two years
ago and that was, of course, the beginning
of a new field, the field of
gravitational wave astronomy.
LIGO's detections before have all been of
black holes, and so we've been waiting
for this event. The news of this
detection first came out on the morning
of August 17th. First there were several
emails sent around to members of the
LIGO and VIRGO Scientific Collaborations
saying that an interesting alert had
been picked up that may or may not have
been a gravitational wave source. The
signal was so loud, internally we knew
there was nothing it could be, besides
what we thought we were sending the
alert for. So we had the gravitational
wave signal and then within a couple
minutes we got another alert that came
in from one of the satellites that had
recorded a signal in gamma rays which
are very high-energy late about two
seconds after the signal. That moment was
the moment that I realized that maybe
this is actually the source that we've
been all waiting for.
What we were seeing in the signal was
the spiral dance, and eventual death, of a
pair of neutron stars. A neutron star is
a collapsed skeleton of a star when the
star explodes and dies it compresses
down to something about the size of a
city and the whole star, more or less, is
composed of ultra dense neutrons. It's
like a giant atomic nucleus the size of
a city. And these two neutron stars
spiraled in towards each other and
actually collided and what we detected,
we detected how these neutron stars
actually rippled the fabric of space
itself. It's just like having two cars
they did crush so this very same thing
also produces light. And this jet is a
source of radiation across the spectrum,
so you go from gamma rays all the way to
radio, so gamma rays, x-rays, UV obstacle
infrared, millimeter and radio,
everything. Because we have this e/m
follow-up, we have a picture of the
galaxy that it came from, you can see the
little pillar nova, you can see how far
from the center of the galaxy that it is,
and based off of what we know about
these type of galaxies, you can kind of
make a model of this galaxy. And that's
the amazing thing with this source. For
the first time, we saw the final
collision of two neutron stars. And for
the first time, we saw this multi-messenger message of combined
gravitational waves and electromagnetic
waves. So right now the thing that we're
worried about is well what did they
become, what happens to two neutron stars
when they combine, did they make one new
gigantic super neutron star, or do they
become a black hole? We don't know. So
this is the beginning of a very exciting
time and this event that we saw actually
highlights also the importance of making
it better. But that's why we do astronomy,
we keep looking because we're going to
pile more and more onto the pile of
things that we've seen, and it will
eventually illuminate that question.
This is of course an amazing feeling to
have solved one long-standing mystery, to
have opened up a new field of multi-messenger astronomy. One might say 'you're
done, okay let's go home!' But in reality
this is just the beginning for us.
Just like when people were first
building telescopes and looking up and
there was amazing things to see that
surprised them, we are now in an era
where we have a new sort of telescope,
and we can look at an entirely new
channel of information. It's one of the
most monumental feats in modern
astrophysics and decades from now, maybe
even centuries from now, people will look
back at this event and say, 'this is where
it started.' It's an exciting time to be
involved with this because we're just
seeing the tip of the iceberg of what
might be possible. Who knows what awaits
us as we discover more of these neutron
star mergers.
 
