Gravitational waves resulting from crashing
neutron stars have rocked our universe once again.
And while you may not have felt it,
LIGO sure did.
And these gravitational waves are the ripples
from a collision of the most massive neutron
star pair we have ever witnessed.
As you may know, this isn't LIGO's first rodeo
with gravitational waves.
They’re famous for the first ever detection
of gravitational waves back in 2015, which
were the result of a black hole merger.
Then LIGO detected their first ever gravitational
waves from a neutron star merger in 2017.
And this latest neutron star collision, observed
in 2019, was given the catchy name...GW190425.
Just as a quick refresher, LIGO is the Laser
Interferometer Gravitational-Wave Observatory.
It detects these tiny disturbances in the
fabric of space-time, like ripples on the
surface of a pond.
They travel through the universe at the speed
of light, and typically only distort physical
space here on Earth by about the width of
an atom’s nucleus.
And even though gravitational waves are practically
infinitesimal by the time they reach us here
on Earth, the strongest ones we can measure
with our instruments are caused by gigantic
cosmic events: like collisions of black holes or
neutron stars.
The 2019 event was actually detected on only one of the two U.S. LIGO sites—the one in Louisiana—
because the detector in Washington
was offline.
This is LIGO’s first single-detector event,
which is impressive, but it also means researchers
weren’t able to narrow down the merger’s
location as much as they might have been able
to with two detectors online.
Though as of right now, the merged neutron stars
could exist anywhere in an area that makes
up about 20% of the sky, not exactly a small
window.
The team deduced from the data that the combined
mass of the two neutron stars was about 3.4
times greater than the mass of our Sun, making
it the most massive neutron star merger we’ve
ever observed.
And it’s different from the 2017 event,
too, because it wasn’t accompanied by any
kind of electromagnetic radiation that we
could detect—it was missing what some scientists
call a ‘flash of light’.
And perhaps most intriguingly, it appears
to have created an object with “unusually
high mass”.
Higher mass than we’ve ever seen before
from a neutron star merger, and higher than
we expected.
With this second observation of neutron stars
colliding, scientists are gathering clues
about how these cosmic events affect our universe.
A neutron star is a super-dense remnant of
a star after it erupts into a supernova.
They’re basically laboratories of really extreme physics.
They tell us a lot about space and how it
evolves over time, so to witness and measure
a collision of two of them can yield some
really rich insights.
Like LIGO’s observation of this in 2017 was the first ever, yes, so very exciting
But it also yielded data confirming the hypothesis
that neutron stars crashing into each other
are a source of heavy elements, producing
stuff like gold and platinum.
They’re basically heavy element factories.
And we still don’t know a lot about what
happens to neutron stars after they merge
together—so scientists were hoping this
latest detection would drop some hints.
All of the data from this 2019 event—the
massive object left behind in the merger’s
wake, plus the lack of electromagnetic radiation—leads
some scientists to believe that these two
neutron stars may have become a black hole
after they merged.
Maybe.
But it could also just be that we weren’t
looking in the right place at the right time
and we missed the flash of light.
So astrophysicists are going to keep probing
this data to see if they can gain any more
insights, and hopefully LIGO will capture
many more events like this in the future to
tell us even more about the crazy cosmic collisions
that both create and disturb the very fabric
of our universe.
In order to do this, LIGO does has some serious upgrades planned, so check out this video here
to learn all about that.
And make sure you subscribe to Seeker for
all things space-time.
If you have another cosmic event you want
to see us cover, let us know down in the comments
below and as always, thanks so much for watching.
I’ll see you next time.
