In the nearby Whirlpool galaxy and its companion galaxy, M51b, two supermassive black holes heat up and devour surrounding material. These two monsters should be the most luminous X-ray sources in sight, but a new study using observations from NASA’s NuSTAR (Nuclear Spectroscopic Telescope Array) mission shows that a much smaller object is competing with the two behemoths.
“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!” said Raffaella Margutti, assistant professor of physics and astronomy at Northwestern University about the mysterious bright object that has baffled astronomers dubbed ‘The Cow’. “A ‘lightbulb’ was sitting deep inside the ejecta of the explosion. 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.”
“It was 11 o’clock on a Sunday night, and I said to myself, ‘I better tell everybody about this,” says Stephen Smartt, an astrophysicist at Queen’s University Belfast and lead scientist for the Hawaii-based ATLAS survey, which first observed the object that has rocked astronomy since its discovery in June, 2018. “I’ve never seen anything like this before in the local universe. It popped up out of nowhere.”
