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#Science

Black hole binary entangled by gravity progressing towards deadly merge

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Scientists have long been looking evidence of black hole binaries as they are thought to be a common occurrence across this vast universe, but haven’t managed to find conclusive evidence until now.

That changed with a new paper published in journal Nature where the authors have provided compelling confirmation of existence of black hole binary entangled in gravity and slowly progressing towards a merger that will prove catastrophic for the surrounding galaxies and stars.

The confirmation of the black hole binary was provided by researchers using data from NASA’s Hubble space telescope and Galaxy Evolution Explorer (GALEX). The binary called PG 1302-102 was first identified using ground-based telescopes earlier this year and according to authors of the latest study, the two black holes are the tightest orbiting pair detected so far.

Study authors say that the separation between the two black holes entangled in gravity is about the same size or probably a little more than the diameter of our solar system and are expected to collide and merge triggering a titanic blast with the power of 100 million supernovae in less than a million years.

Researchers have long advocated presence of such black hole binaries, which they say is a common occurrence, but only a handful have been confirmed so far. PG 1302-102 is one of such binaries and was first discovered and reported by a team of researchers at the California Institute of Technology in Pasadena after they spotted and scrutinized an unusual light signal coming from the center of a galaxy.

Researchers said at the time, based on their observations using the Catalina Real-Time Transient Survey, that the varying signal is most probably generated by the motion of two black holes orbiting each other over a period of five years. While the black holes themselves don’t give off light, the material surrounding them does.

The latest study provides confirmation of the black hole binary using based on evidence obtained on ultraviolet data from GALEX and Hubble. Researchers dug up data from the last 20 years and using this archived data they were able to track the binary black hole system’s changing light patterns.

This simulation helps explain an odd light signal thought to be coming from a close-knit pair of merging black holes, PG 1302-102, located 3.5 billion light-years away. Credits: Columbia University

This simulation helps explain an odd light signal thought to be coming from a close-knit pair of merging black holes, PG 1302-102, located 3.5 billion light-years away.
Credits: Columbia University

“We were lucky to have GALEX data to look through,” said co-author David Schiminovich of Columbia University in New York. “We went back into the GALEX archives and found that the object just happened to have been observed six times.”

Researchers say that the ultraviolet light observations proved critical for the confirmation of the black hole binary and allowed them to test a prediction of how the black holes generate a cyclical light pattern.

Researcher predicted that one of the black holes was giving away more light because it was gobbling up matter faster than the other and as more material is sucked in, the more heating up of the matter around the black hole takes place and that’s what ends up emitting energetic light.

As this black hole orbits around its partner every five years, its light changes and appears to brighten as it heads toward us, researchers added.

“It’s as if a 60-Watt light bulb suddenly appears to be 100 Watts,” explained Daniel D’Orazio, lead author of the study from Columbia University. “As the black hole light speeds away from us, it appears as a dimmer 20-Watt bulb.”

Blue shifting effect is one of the reasons for the changes in light in which light is squeezed to shorter wavelengths as it travels toward us in the same way that a police car’s siren squeals at higher frequencies as it heads toward you. Another reason has to do with the enormous speed of the black hole.

According to authors of the study, the brighter black hole of the two is really fast – about 7 per cent of speed of light – and because of the speed, light becomes boosted and brighter.

“We are strengthening our ideas of what’s going on in this system and starting to understand it better,” said Zoltán Haiman, a co-author from Columbia University who conceived the project.

The results will also help researchers understand how to find even closer-knit merging black holes in the future, what some consider the holy grail of physics and the search for gravitational waves. In the final moments before the ultimate union of two black holes, when they are tightly spinning around each other like ice skaters in a “death spiral,” they are predicted to send out ripples in space and time. These so-called gravitational waves, whose existence follows from Albert Einstein’s gravity theory published 100 years ago, hold clues about the fabric of our universe.

The findings are also a doorway to understanding other merging black holes across the universe, a widespread population that is only now beginning to yield its secrets.