https://phys.org/news/2020-10-black-hole-chirps-scientists-clues.html The black hole always chirps twice: Scientists find clues to decipher the shape of black holes by ARC Centre of Excellence for Gravitational Wave Discovery Please Register or Log in to view the hidden image! Black hole cusp. Credit: ARC Centre of Excellence for Gravitational Wave Discovery A team of gravitational wave researchers led by the ARC Center of Excellence for Gravitational Wave Discovery (OzGrav) report that when two black holes collide and merge, the remnant black hole "chirps" not once, but multiple times, emitting gravitational waves—intense ripples in the fabric space and time—that reveal information about its shape. Their study has been published in Communications Physics. Black holes are among the most fascinating objects in the universe. At their surface, known as the event horizon, gravity is so strong that not even light can escape. Usually, black holes are silent objects that swallow anything that falls too closely to them; however, when two black holes collide and merge, they produce one of the most catastrophic events in universe: In a fraction of a second, a highly deformed black hole forms and releases tremendous amounts of energy as it settles to its final state. This phenomenon gives astronomers a unique chance to observe rapidly changing black holes and explore gravity in its most extreme form. Although colliding black holes do not produce light, astronomers can observe the detected gravitational waves they create—ripples in the fabric of space and time. Scientists speculate that, after a collision, the behavior of the remnant black hole is key to understanding gravity and should be encoded in the emitted gravitational waves. In the article published in Communications Physics, the scientists, led by OzGrav alumnus Prof. Juan Calderón Bustillo, reports how gravitational waves encode the shape of merging black holes as they settle into their final form. more at link.................
