Last June, an incredibly bright supernova known as “The Cow” ripped across the sky, hovering above the Earth for a number of weeks. While The Cow provided significant excitement for astronomers, who learned it traveled 200 million light-years, new research suggests that it was the birth of a black hole or neutron star, a first in the history of mankind.
After looking at several images, hard X-rays and microwaves of the object officially known as AT2018cow, researchers determined that their telescopes captured the exact moment a star collapse and a black hole was formed. The bright glow was caused by the debris swirling around its event horizon, astonishing the researchers.
“We think that ‘The Cow’ is the formation of an accreting black hole or neutron star,” said Northwestern’s Raffaella Margutti, who led the research, in a statement. “We know from theory that black holes and neutron stars form when a star dies, but we’ve never seen them right after they are born. Never.”
The team used observational facilities at the W.M. Keck Observatory in Hawaii and the MMT Observatory in Arizona, as well as remote access to the SoAR telescope in Chile to look at the object’s makeup. They found that it was composed of hydrogen and helium.
The relatively clean makeup helped astronomers, Margutti added.
“A ‘lightbulb’ was sitting deep inside the ejecta of the explosion,” Margutti said. “It would have been hard to see this in a normal stellar explosion. But The Cow had very little ejecta mass, which allowed us to view the central engine’s radiation directly.”
The findings were presented at the American Astronomical Society on Thursday and the research will eventually be published in the Astrophysical Journal.
The Cow disappeared as quickly as it appeared. It lost most of its energy in 16 days, despite being an unusually bright anomaly – 10 to 100 times brighter than a typical supernova.
“In a universe where some phenomena last for millions and billions of years, two weeks amounts to the blink of an eye,” the statement said.
“We knew right away that this source went from inactive to peak luminosity within just a few days,” Margutti added. “That was enough to get everybody excited because it was so unusual and, by astronomical standards, it was very close by.”
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