The universe finds gravitational-wave predators with strange black holes. Science

Less than 5 years ago, physicists shook the scientific world when they first saw the ephemeral waves of space and time as gravitational waves when black holes penetrated each other two billion light-years away. Since then, scientists have found a scad of similar events, mostly reported chronologically. Today, however, researchers with a global network of gravitational wave detectors announced the first ever large-scale statistical analysis of their data, totaling 50 events. Posted online in four papers, the analysis shows that black holes – formerly left behind by ultra-gravitational fields when large stars break up – are more common and unfamiliar than expected. They also shed light on mysteries such as how such black holes connect before merging.

Carl Rodriguez, an astrophysicist at Carnegie Mellon University who was not involved in the work, says the new study, posted on the physics printprint server archive, is “very important.” “With an individual event, you can do a lot more than astrophysics models. But with catalogs you can not only begin to tie the theory, you can begin to understand the landscape. “Selma de Mink, an astrophysicist at Harvard University, says she and her colleagues are waiting to do their own analysis of the data. There will certainly be a flurry of papers rushing to take the first shot at the data.”

These observations are made by three large L-shaped optical instruments called interferometers that can measure the infinite stretch of space by a gravitational wave. Two of those detectors are from the Laser Interferometer Gravity-Wave Observatory (LIGO), a pair of detectors with 4-kilometer-long arms in Louisiana and Washington state, which first detected gravitational waves in 2015. The third detector is an interferometer near Pizza, Italy, which has a 3 km long weapon and joined the hunt for gravitational waves in 2017.

LIGO and Virgo have already discovered 11 events, including a merger of neutron stars, which will shed light on how the universe will create heavier elements. Now the team has cut a possible black hole and neutron star merger from the first part of its third observation race from April to September 2019, 37 additional black hole mergers, a possible neutron star merger.

An analysis of all 50 events shows that when it comes to black holes, “diversity is surprisingly large,” says gravitational wave astronomer Frank Ohm of the Max Planck Institute for Gravitational Physics. From the details of such signs as the merger chip, scientists can calculate the mass of the colliding black hole. They expected to find a “mass distance” between about 45 and 135 solar masses – the result of particle physics processes that would scatter stars in a certain mass range before they could fill black holes.

However, Ligo and Virgo have now discovered a merger involving a black hole in the gap, with a mass of about 85 solar masses. The Minek, which models the evolution of black-hole pairs from binary star systems, says it would be challenging for interlocutors to calculate. He says that the mass gap in the mass spectrum “is such a clear prediction of models that it is difficult to believe that there is no facility”.

Similarly, scientists expected another restricted series below 5 solar births, which peacefully orbit normal stars based on previous observations of normal black holes. But at least one hole in the catalog appears to be falling below that limit. “How can you describe the boundaries of this population?” Ohm asks. “It’s not such a clear picture anymore,” he says.

Their new ability to take black hole censuses has also enabled researchers to examine whether black holes in a merged pair move in the same direction as each other’s orbits – a potential key to how the pair came together in the first place. If the spin aligns with the orbital axis, black holes can form from a pair of stars that are born together, receive a naturally matched spin, and remain mates after the fall. If the spins point in different directions, the black hole will probably be formed first and then paired later. Which creation channel dominates is the subject of intense debate.

In particular, if a black hole spins in the opposite sense of orbit, the pair merges into more black holes that have already formed. Maya Fishbach, an astrophysicist and LIGO member at Western University, says it’s hard to say for sure if it’s happening with a single signal warbler. However, primarily by analyzing events, scientists have provided evidence that at least some of the mergers involved reverse spin. The result suggests that black-hole pairs are formed in more than one way, Fishbach says. “Looks like a lot of things can go on there.”

Rodriguez notes that the overall rate of black hole mergers that LIGOs and Virgos see seems to be roughly the same as predicted in their model in which pre-formed black holes find each other and join a cluster of old stars called globular clusters. He says, “I shouldn’t break my own horn – but I’m going to go completely,” he says. But he notes that the data, just a quarter of the merger, are also consistent with the method of producing Rodriguez notes.

Fishbach says researchers have also been able to investigate how the number of black hole mergers can change over cosmic time. This rate is expected to be higher in the early universe, while the speed of star formation was also higher. But previous data has allowed that rate to be 100,000 times higher than it is now. Fishbach says that now, scientists have seen far-reaching events that could be called merger rates 8 billion years ago.

Scientists at Ligo and Virgo take advantage of their scientific sensibility for their detectors’ increasing sensitivity, which has enabled them to detect obscure and more distant events. Now they are still eager to make their list. As more events unfold, they explore the relationship between spin alignment and black hole people which can help reveal whether the merger has produced the heaviest self. (If two black hole spins are not aligned, then they cannot be formed from a separate pair of stars, and theoretically a broken star does not need to explain how such a massive black hole can be produced.) “We answered many questions. We didn’t even know we had it, “says Fishbach,” but we’ve raised more. This is the beginning of science. ”