Black holes are the most amazing things in the universe. On their surface, known as the “event horizon”, gravity is so strong that even light cannot escape from them. In general, black holes are quiet, quiet creatures that swallow anything approaching them; However, when two black holes collide and merge together, they create the most destructive events in the universe: in a fraction of a second, a very distorted Black hole It releases tremendous energy when it is born and stabilizes in its final form. 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 and observe. Gravitational waves – ripples in the fabric of space and time – it bounces them. 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.
Artist’s depiction of part of a black hole. Credit: C. Evans; Jesse Bustillo
In the article published in Communications Physics (Nature), a former student of Ozgrav Pro. A team of scientists led by Juan Calderનn Bustillo – now at the Galician Institute for High Energy Physics (Santiago de Compostela, Spain) – La Caxa Jr. Leader – Marie Curie Fellow – how to shape gravitational waves Settles in their final form.
Christopher Evans, a graduate student and co-author of the Georgia Institute of Technology (USA), says: “We simulated black-hole collisions using supercomputers and then compared the rapidly changing shape of the remaining black holes with gravitational waves. We found that these signs are much richer and more complex than we normally would consider, allowing us to learn more about the massive changing shape of the final black hole. “
First, the two black holes orbit each other, gradually approaching, during the inspirational phase. The other two black holes merge, creating a distorted black hole. In the end, the black hole reaches its final form. B: The frequency of gravitational-wave signals is observed from the top of the collision (on the left side) and as a function of time at its equator (rest) from different positions. The first signal shows a typical “churching” signal, in which the frequency increases as a function of time. The other three show that after the collision (at t = 0) the frequency decreases and increases again, producing another “chip”. Credit: c. Evans, j. Calderon Bustillo
Gravitational waves hitting a black hole are very 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. According to Calderon Bustillo, “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, like the sound of a bell, emits a signal with a constant pitch and decreasing amplitude. When studying, this theory is consistent with all gravity-wave observations so far.
However, the study found that the collision from the “equator” of the final black hole is completely different if observed. “When we looked at the black holes from their equator, we found that the final black hole, going up and down a few times before a pitch dies, emits a more complex signal.” “In other words, black holes actually chip in many times.”
Details of the shape of a black hole burned after a black hole collision, with a ‘chestnut shape’. Gravity-wave emission (in yellow) regions of the cluster near its group. These black hole spins signal to all observers around it. Credit: c. Evans, j. Calderon Bustillo
The team discovered that this is related to the shape of the final black hole, which acts like a kind of gravitational-wave lighthouse: Is, shade on one side and wide on one side, smooth on the other. “It turns out that a black hole emits more intense gravitational waves through its most curved spheres, which surround it. This is because the remaining black hole also spins and its part and back repeatedly point to all observers, producing multiple chips. “
Co-author Pro. Pablo Laguna, a former president of the School of Physics at Georgia Tech and now a professor at the University of Texas at Austin, points out that “the relationship between gravitational waves and the behavior of the final black hole has long been speculated. , Our study provides the first clear example of this type of relationship. “
Ref: 8 October October 2020, Communications Physics.
DOI: 10.1038 / s42005-020-00446-7
