Astronomers may have spotted light from colliding black holes

This artist's concept shows a supermassive black hole surrounded by a disk of gas. Embedded in this disk are two smaller black holes that may have merged together to form a new black hole

Black hole merger in deep space suggests universe’s darkest beings can create light

Dr. Laura Nuttall, a gravitational wave expert from the University's Institute of Cosmology and Gravitation, said: "The reason these findings are so exciting is because we've never detected an object with a mass that is firmly inside the theoretical mass gap between neutron stars and black holes before". This might bring about more insights in to the study of blackholes.

These disks also help draw black holes together, and the reaction of the gas and dust under the huge pressure of a black hole merger help to create a "kick" of light, according to the research published in the journal Physical Review Letters.

However, it's an ironic twist of fate that when two black holes merge in a cataclysmic event, they can also produce a flare of light as powerful as a trillion suns. This was followed by the detection of electromagnetic radiation in the form of flares right near the same spot of the gravitational wave.

The scientists provide evidence that the black hole may have collided with another, producing an unexpected flare in space. Prior to the discovery, black holes were thought to merge in stellar graveyards, where there is little gas or dust that can heat up and glow.

If nothing can escape the gravity of black holes, how did they emit this intense flare of light? However, theorists have come up with ideas about how a black hole merger could produce a light signal by causing nearby material to radiate. Accretion disks are ubiquitous phenomena in astrophysics where it involves gamma ray bursts. "But in a supermassive black hole's disk, the flowing gas converts the mosh pit of the swarm to a classical minuet, organizing the black holes so they can pair up", she says.

The co-author of the study, Barry McKernan said, "It is the reaction of gas to this speeding bullet that creates a bright flare visible with telescopes". So far, such light counterparts to gravitational-wave signals have been seen only once, in an event called GW170817. "We conclude that the flare is likely the result of a black hole merger, but we can not completely rule out other possibilities".

The LIGO/Virgo collaboration is yet to confirm what type of colossal cosmic event occurred but that, if it was as the researchers suspect, the merged black hole's mass would now sit at around 150 solar masses, which would be the largest ever recorded. Scientists compared the two events and found out that they came from the same region of the sky. ZTF observed the flare slowly fade over the period of a month. The event (called S190521g) was first identified by the National Science Foundation's (NSF) Laser Interferometer Gravitational-wave Observatory (LIGO) and the European Virgo detector on May 21, 2019. The research team believed that it was in such a location that the pair of black holes merged, an act that disturbed the surrounding space dust and debris and caused the flare as a result. However, the researchers say they were able to largely rule out other possible causes for the observed flare, including a supernova or a tidal disruption event, which occurs when a black hole essentially eats a star. Using the Catalina Real-Time Transient Survey, led by Caltech, they were able to assess the behavior of the black hole over the past 15 years, and found that its activity was relatively normal until May of 2019, when it suddenly intensified. "Supermassive black holes like this one have flares all the time", co-author Mansi Kasliwal, an astronomer at Caltech, said in the statement.

"There's a lot we can learn about these two merging black holes and the environment they were in based on this signal that they sort of inadvertently created".

"This detection is extremely exciting", said Daniel Stern, coauthor of the new study and an astrophysicist at NASA's Jet Propulsion Laboratory in Southern California, which is a division of Caltech. Through its almost 40 centers, institutes, and initiatives, including its Advanced Science Research Center (ASRC), The Graduate Center influences public policy and discourse and shapes innovation.

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