Black Hole Birth or Neutron Star Formation Captured by Telescopes, Astronomers Believe

James Marshall
January 13, 2019

Eventually the scientific community began to call him "Cow". The stellar collapse was about 10 to 100 times brighter than a typical supernova, and it reached that peak quite quickly. "The Cow" is located in a relatively nearby galaxy - only 200 million light years away from our own Milky Way galaxy in the direction of the constellation Hercules.

The June 16 detection came from Hawaii's ATLAS telescope, which surveys the night sky for supernovas and other powerful, short-lived phenomena.

But the team still isn't sure exactly what The Cow is. This gave rise to assumptions that astronomers had witnessed the birth of a black hole. "It would have been hard to see this in a normal stellar explosion".

Scientists presented their observations of The Cow this week at the 233rd meeting of the American Astronomical Society in Seattle.

Scientists might have witnessed the formation of a black hole for the first time.

A Black Hole Shredding a Compact Star?

After it was first spotted, The Cow captured immediate global interest and left astronomers scratching their heads. The tail of the gas stream is flung out of the system, but the leading edge swings back around the black hole, collides with itself and creates an elliptical cloud of material. After ATLAS spotted the object, Margutti's team quickly conducted follow-up observations using multiple observatories to analyze The Cow in different wavelengths.

It was surely something that scientists had never seen before, and they wanted to solve the mystery quickly.

A Northwestern University-led global team is getting closer to understanding the mysteriously bright object that burst in the northern sky this summer. They also calculated that the black hole's mass ranges from 100,000 to 1 million times the Sun's, nearly as large as the central black hole of its host galaxy.

Our team used high-energy X-ray data to show that the Cow has characteristics similar to a compact body like a black hole or neutron star consuming material. Meanwhile, others say the explosion may have been caused by a pre-existing black hole ripping apart a white dwarf star.

The new study viewed the object with X-rays, hard X-rays which are 10 times more powerful than normal X-rays, radio waves and gamma rays.

By "compact", Margutti refers to a dense body such as a neutron star or even a black hole. The Cow could represent the birth of one of these stellar remnants. Lead paper author Raffaella Margutti says that based on X-ray and UV emissions, The Cow may have been caused by a black hole as it swallowed up a white dwarf star.

She added that the radio data suggests that the unique Cow explosion was being continuously energized by either a black hole or a magnetar at its core. "We thought it must be a supernova", Margutti said.

The team studied data from several observatories, including NASA's NuSTAR, the European Space Agency's XMM-Newton and INTEGRAL satellites, and the National Science Foundation's Very Large Array, a USA radio-based observatory.

Margutti is an assistant professor of physics and astronomy in Northwestern's Weinberg College of Arts and Sciences and a member of CIERA (Center for Interdisciplinary Exploration and Research in Astrophysics), an endowed research center at Northwestern focused on advancing astrophysics studies with an emphasis on interdisciplinary connections.

"Two hundred million light-years is close for us", said Margutti. Study coauthor Brian Grefenstette, an instrument scientist at Caltech, explained that "if we're seeing the birth of a compact object in real time, this could be the start of a new chapter in our understanding of stellar evolution". "But, as we're seeing with the Cow, that doesn't mean the solution will be simple", he concluded. NuSTAR was developed in partnership with the Danish Technical University and the Italian Space Agency (ASI).

Other reports by Click Lancashire

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