The Theory of Relativity, published in 1905 by Albert Einstein, postulated the existence of gravitational waves—oscillations of the space-time fabric—and more than a century later, we have irrefutable evidence of it. Now, a new study has managed to find clear indications of relativistic precession in the orbits of two colliding black holes.
The science and other stuff to know
Since gravitational waves were first detected in 2015, this
has become a fertile field for modern astrophysics, allowing experts to spot
phenomena they were previously blind to.
The merger of black holes is undoubtedly one of the most
colossal and violent events that can be conceived. The apocalyptic dance that
the two bodies perform as they approach their inexorable destiny, and the
fusion itself, involves so much energy that the fabric of space-time is shaken
as if it were a sheet.
Thanks to detectors called interferometers, we can track
these events from Earth and find out what event gave rise to these waves and
what region of the universe they come from. The GW200129 signal was detected in
2020 and comes from the deadly gravitational dance of two massive black holes.
Now, a team of researchers from Cardiff University observed
a strange twisting motion in the orbits of two colliding black holes, a
phenomenon predicted by Einstein, a press release states.
Their study, which has been published in Nature, deduced
that, before merging, these black holes rotated, presenting what is known as
relativistic precession: the tendency of an orbit to be perturbed and change
cyclically. A top, for example, is a clear example: it begins to rotate on its
vertical axis —not rotational— and eventually, the axis twists and begins to
rotate. This happens with the orbits of all systems where the gravity of one
body affects the other, and tends to be a negligible effect.
But the case of GW200129 is exceptional due to the speed of
precession of the system; it is 10 billion times stronger than the fastest
precession measured up to its detection—75 years.
So what?
In addition to continuing to provide evidence in favor of
Relativity—one of the most complete physical theories and with the greatest
predictive power—, this detection speaks of the ability that the gravitational
wave field has developed to detect phenomena that are increasingly weaker at
energy levels.
The refinement of data analysis techniques and the
collaborations between the LIGO, Virgo, and KAGRA interferometers are making it
possible to obtain more precise measurements.
What’s next?
The network of interferometers extended between the United
States (LIGO), Europe (Virgo), and KASGRA (Japan) is currently out of service
as they are carrying out maintenance on the delicate design of the experiment.
They will retake data in 2023 and track new events of this type and, hopefully,
many other unknown ones.
“So far most black holes we’ve found with gravitational
waves have been spinning fairly slowly,” said co-author Charlie Hoy, in a press
release. “The larger black hole in this binary, which was about 40 times more
massive than the Sun, was spinning almost as fast as physically possible. Our
current models of how binaries form suggest this one was extremely rare, maybe
a one in a thousand event. Or it could be a sign that our models need to change.”
The researchers hope to continue detecting phenomena of this
type. After all, the first detection of something always gives us the wrong
impression that what we have found is unique. Still, it is enough to refine our
measurements and instruments to realize that it is just one more specimen among
hundreds of thousands of others.
Reference:Nature
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