In 2019, the LIGO/VIRGO collaboration captured a gravitational wave signal from a black hole merger that turned out to be one of the most record-breaking. Dubbed “GW190521”, it was the most massive and farthest of all and produced the most energetic signal yet detected and appeared in the data as a “pop” rather than the usual “chirp”.
Also, the new black hole resulting from the merger was about 150 times heavier than our sun, making GW190521 the first direct observation of an intermediate-mass black hole. Even stranger, the two black holes that merged were confined to an elliptical (not circular) orbit, and their spin axes were much more inclined than normal for those orbits.
Physicists love nothing more than to be confronted with an intriguing puzzle that does not immediately seem to fit in well-established theory, and GW190521 gave them just that. New theoretical simulations suggest that all of these strange aspects can be explained by the presence of a single black hole in the binary system’s last dance to create a “chaotic dance”. new paper Published in Nature magazine.
as we are Previously mentionedOn May 21, 2019, the collaboration’s detectors picked up the telltale telltale signal of a black hole binary merger: four short pulses lasting less than a tenth of a second. The shorter the signal, the greater the mass of the merging black holes – in this case, 85 and 66 solar masses, respectively. The black holes merged into a new, larger black hole of about 142 solar masses, releasing the equivalent of 8 solar masses, hence the strong signal picked up by the detectors.
What made this event so unusual is that the measurement of 142 solar masses lies in the middle of the so-called “mass gap” of black holes. Most of these objects belong to two groups: stellar mass black holes (ranging from a few solar masses to tens of solar masses) and supermassive black holes such as those at the center of our galaxy, the Milky Way (ranging from hundreds of thousands to billions of solar masses). The former is the result of massive stars dying in a collapsing supernova, while the process of formation of the latter remains a mystery.
The fact that one of the ancestors of black holes weighed 85 solar masses is also very unusual, and contradicts current models of stellar evolution. The types of stars that produce black holes between 65 and 135 solar masses will not become supernovae, and therefore will not end up as black holes. On the contrary, these stars will become unstable and lose a significant part of their mass. Only then will they turn into a supernova, but the result will be a black hole of less than 65 solar masses.
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