Numerical simulation of two black holes emitting gravitational waves. Black holes have large and almost identical masses, with only 3% being larger than one. The simulated gravitational wave signal is consistent with the observation made on May 21, 2019 (GW 190521) by LIGO and Virgo Gravity Wave Detectors. Credit: Credit: n. Fisher, H. Pfeiffer, a. Bunanno (Max Planck Institute for Gravitational Physics), Simulating Extreme Spacetime (SXS) Collaboration
A binary Black hole The merger has produced potential Gravitational waves The equivalent of eight suns.
For all its vast emptiness, the universe is buzzing with activity in the form of gravitational waves. Produced by extreme astrophysical phenomena, these rethinking move forward and shake the fabric of space-time like the clang of a cosmic brick.
Now researchers have found a signal from what could be in the largest black hole merger observed in gravitational waves. The merger product is the first apparent discovery of an “intermediate-mass” black hole that contains 100 to 1000 times the mass of the Sun.
On May 21, 2019, they discovered a signal labeled the National Science Foundation’s laser interferometer gravity-wave observatory (GW190521).LIGO), A pair of identical, 4-kilometer-long interferometers in the United States; And the Vir kilometer long detector Virgo in Italy.
The signal, similar to about four short wiggles, is very short in duration, lasting less than a tenth of a second. From what researchers might say, GW 190521 was created by a source about 5 gigaparsec away, while the universe was half its age, making it one of the most distant gravitational-wave sources ever.
Based on a powerful suite of advanced computational and modeling tools, what constitutes this signal, scientists believe that GW190521 was created by a binary black hole merger with possibly unusual properties.
Nowadays almost every confirmed gravity-wave signal has been made by a binary merger, between two black holes or two neutron stars. This newest merger yet appears to be quite large, involving two inspiring black holes, about 85 to 66 times and the mass of the Sun.
: This artist’s idea illustrates a hierarchical plan to merge black holes. Ligo and Virgo recently observed a black hole merger with a final mass 142 times that of the Sun, the largest of its kind seen in today’s gravitational waves. Credit: LIGO / Caltech / MIT / R Hurt (IPAC)
The LIGO-Virgo team also measured the spin of each black hole and discovered that the black holes were always orbiting each other, so they rotated about their own axes, at an angle aligned with their own orbital axis. The black holes spun incorrectly, causing their orbits to tremble, or become “precessive,” as the two Goliaths turned toward each other.
The new signal probably represents that the two black holes merged. The merger created a much larger black hole, about 142 solar births, and the equivalent of about 8 solar masses spread across the universe in the form of gravitational waves, releasing an abundance of radiation.
“It doesn’t look like much of a church,” said Nelson Kristens, a researcher at the National Center for Scientific Research (CNRS) in France, who compared it to the first probe signal of gravitational waves. 2015. “This is something that ‘bangs’, and it’s the biggest signal that LIGO and Virgo have seen.”
The LIGO Scientific Collaboration (LSC) and the International Team of Virgin Collaborating Scientists reported their findings in two papers published today. One, appears inside Physical Review Letters, Search details and others Astrophysical Journal Letters, Discusses the physical properties and astrophysical effects of the signal.
Pedro Maronetti, program director of the National Science’s Gravity Physics program, says: Says Pedro Maronetti, program director of the National Science’s Gravity Physics Foundation. “This is extremely important because it demonstrates the tool’s ability to detect signals from completely unexpected astrophysical events. LIGO shows that it can also make unexpected observations. “
In the mass distance
The two inspiring black holes, as well as the uniquely large masses of the final black holes, raise many questions regarding their composition.
All of the black holes observed so far fall into one of two categories: stellar mass black holes, which measure from a few solar births to ten solar masses and form when large stars die; Or a supermassive black hole, like the one in the middle Milk Ganga The galaxy, which is in the thousands to billions of times our sun.
However, the final 142-solar-mass black hole produced by the GW190521 merger lies within the intermediate mass between stellar-mass and supermassive black holes – the first of its kind to be discovered.
The two preschool black holes that produced the final black hole also look unique in their size. They are so vast that scientists suspect that one or both of them may not have formed from a collapsing star, as most stellar-mass black holes do.
According to the physics of the evolution of stars, the external pressure of photons and gases in the core of the star pushes inward against the pressure of gravity, so that the star is as stable as the sun. After fusing the nucleus as hard as iron in the center of a large star, it will no longer be able to generate enough pressure to support the outer layers. When this external pressure is less than gravity, the star collapses under its own weight, in an explosion called a core-collapse ledge supernova, which could leave behind a black hole.
This process could explain why stars as large as 130 solar masses can produce black holes that are 65 solar masses. But for heavy stars, the phenomenon known as “pair instability” is thought to have begun. When the photons in the core become extremely powerful, they can morph into an electron and antelectron pair. This pair produces less pressure than a photon, which causes the star to become unstable against gravitational collapse, and the resulting explosion is so strong that it leaves nothing behind. Stars larger than 200 solar masses will eventually fall directly into the black hole of at least 120 solar masses. A collapsed star, then, should not be able to generate a black hole between about 65 and 120 solar masses – a series known as the “pair instability mass gap”.
But now, 85 heavier than the 85 black holes that produced the GW190521 signal, 85 solar masses, the first ever discovered within the mass distance of the pair’s instability.
“The fact that we’re seeing black holes in this mass interval, a lot of astrophysicists will scratch their heads and try to figure out how these black holes were created,” says Christensen, director of the Artemis Laboratory. Nice observatory in France.
One possibility, which the researchers considered in their second paper, is a hierarchical merger, in which two pre-existing black holes formed themselves, migrating together and merging into two smaller black holes before finally merging.
“This event opens up more questions than it provides answers,” says Weil Weinstein, a LIGO member and professor of physics at Caltech. “From a research and physics point of view, it’s a very exciting thing.”
“Something unexpected”
There are many questions regarding GW190521.
As LIGOs and virgin detectors hear gravitational waves passing through the earth, automatic detection combs through incoming data for interesting signals. These discoveries can use two different methods: algorithms that select specific wave samples in the data that can be generated by compact binary systems; And find the more common “explosion” that uniquely finds anything.
LIGO member Salvatore Vital, assistant professor of physics at MIT, In contrast to compact binary detection with “passing comb through data, which will catch objects at a certain distance”, the “catch all” approach compares to explosion detection being more.
In the case of GW190521, it was an explosion detection that chose the signal a little more clearly, opening up a very small chance that gravitational waves originated from anything other than a binary merger.
“The belt is too short to say we’ve found something new,” says Weinstein. “So we usually apply Ocadam razor: a simpler solution is better, which in this case is a binary black hole.”
But what if something new produces these gravitational waves? That is the uncertain future, and in their paper the scientists briefly consider other sources in the universe that may have produced the signal they discovered. For instance, gravitational waves were probably coming out of the galaxy’s broken stars. This sign may also be of cosmic strings generated after inflating in the early moments of the universe – although none of these foreign possibilities match the data and the binary merger.
“Ever since we first turned on LIGO, what we have confidently observed is a collision of black holes or neutron stars,” says Weinstein, “this is a phenomenon where our analysis allows the possibility that this phenomenon did not occur.” This phenomenon is consistently consistent with large-scale binary black hole mergers, and optional disclosures are ignored, pushing the boundaries of our faith, and potentially making it even more exciting, because we all hope for something new, unexpected. What we have already learned can be challenging. This event is likely to do just that. “
To learn more about this research read the quickest ‘bang’ signals the largest source of gravity-wave.
Reference:
R. “GW190521: Binary Black Hole Merger with Total Mass 150 M⊙” by Abbott et al. (LIGO Scientific Collaboration and Virgo Collaboration), 2 September 2020, Physical Review Letters.
DOI: 10.1103 / fizrivate.125.101102
R. Abbott, TD Abbott, s. Abraham, f. Esarnis, k. Ck Clay, c. “Properties and Astrophysical Implications of 150 Solar Mass Binary Black Hole Merger GW 190521” by Adams, RX Officer, VB Adya, C. Efeldt. M. Agathos September 2, 2020, Astrophysical Journal Letters.
DOI: 10.3847 / 2041-8213 / ABA 493
The research was commissioned in the U.S. Funded by the National Science Foundation.
