Scientists are looking for clues to understand the shape of black holes

A team of gravitational wave researchers led by the ARC Center Excel for Excellence for Gravitational Wave Discovery (Ozgrav) reported that when two black holes collide and merge, the residual black hole is not once, but often intense gravitational waves. doing. The space and time of the fabric – which reveals information about its shape. His study has been published in Communications Physics.

Black holes are one of the most interesting things in the universe. On their surface, known as the horizon of phenomenon, gravity is so strong that even light cannot escape. In general, black holes are silent objects that swallow anything that comes close to them; However, when two black holes collide and merge, they create the most destructive event in the universe: in a fraction of a second, a very distorted black hole forms and releases tremendous energy as it settles in its final state. This phenomenon gives astronomers a unique opportunity to observe rapidly changing black holes and to explore gravity in its most extreme form.

Although light does not produce collisions with black holes, astronomers can detect gravitational waves created by them – ripples in the fabric of space and time. Scientists speculate that, after a collision, the behavior of a residual black hole is key to understanding gravity and should be encoded in the emitted gravitational waves.

In the article published in Communications Physics, Ozgrav Alumni Scientists led by Juan Calderon Bustillo report on how gravitational waves encode the merging shapes of black holes as they settle into their final form.

Christopher Evans, a graduate student and co-author of the Georgia Institute of Technology (US), says, “We simulated a black-hole collision using supercomputers and then compared the rapidly changing shape of the remnant black hole to that of gravitational waves. Discovered that these signals are much richer and more complex than previously thought, allowing us to learn more about the massively changing shape of the final black hole. ”

Gravitational waves hitting a black hole are simple signals known as “chips”. As the two black holes approach each other, they emit an increasing frequency and amplitude signal indicating the speed and radius of orbit. Pro. Calderon Bustillo says, “The pitch and amplitude of the signal increase as the two black holes reach faster and faster. After the collision, the final remnant black hole emits the signal with a constant pitch and decaying amplitude, like sound. This theory is consistent with all gravitational-wave observations so far when studying collisions from the top.

However, studies have found that something completely different if a collision is observed from the “equator” of the final black hole. “When we observed the black holes from their equator, we found a more complex signal coming out with a pitch that went up and down a few times before the final black hole died.” “In other words, black holes actually chip in many times.”

The team found that this is related to the shape of the final black hole, which acts like a kind of gravity-wave lighthouse: “When the two original parent black holes are of different sizes, the final black hole initially looks like a chest, bustillo. It turns out that a black hole emits more intense gravitational waves through its most curved spheres, which surround its sacred area. This is because the residual black hole also spins and is indicated to all observers on its part and back, producing many chips. ”

Prof. Pablo Laguna, a former president of the School of Physics at Georgia Tech and now a professor at the University of Texas at Texas at Austin, co-author. While the relationship between gravitational waves and the behavior of the final black hole has been a long one, Pablo Laguna said. Presumably, our study provides the first clear example of this type of relationship. ”