A flash of light in the night sky was a star falling prey to a black hole, Axios reported. Half the star was consumed by the black hole and the other half was ejected away from it, one astronomer said. The Great Courses’ Mind-Blowing Science course has more.
According to Axios, a rarity of astronomy has been detected from a great distance. “Scientists have spotted a bright flash of light emitted by a star as it was destroyed by a black hole 215 million light-years away,” the article said. “Black holes are some of the most extreme and difficult to study objects in the universe, and these types of rare events could help researchers piece together more about their nature.
“A new study detailing the death of the star […] explains that the star went through an event called ‘spaghettification’ where it was ripped apart when it came too close to a supermassive black hole.”
Dr. Priyamvada Natarajan, Professor of Astronomy in the Department of Physics at Yale University, wrote an article for Scientific American about early supermassive black holes. The Great Courses partnered with Scientific American to bring some of their finest articles to life with our new course Mind-Blowing Science and adapted Dr. Natarajan’s article, “The First Monster Black Holes,” for one of our lectures. Here’s what we discovered.
The Quasar Conundrum
According to Dr. Natarajan, the oldest galaxies appeared in space about 400 million years after the birth of the universe. Around this same time, quasars were also born.
“Quasars are extremely bright objects powered by gas falling onto supermassive black holes,” she said. “They are some of the most luminous things in the universe, visible out to the farthest reaches of space. The most distant quasars are also the most ancient, and the oldest among them pose a mystery.”
That mystery is that in order for quasars to be visible from such distances, they would have to be fueled by black holes a billion times the mass of the sun, and yet black holes that size would have to be formed over the course of about a billion years—not the 400 million years after the birth of the universe to which many quasars date. In other words, the earliest quasars somehow appeared at least 600 million years before they should have, even from the earliest black holes—also known as seed black holes.
“To solve this quandary, a decade ago, some colleagues and I proposed a way that seed black holes massive enough to explain the first quasars could have formed without the birth and death of stars,” Dr. Natarajan said. “Instead these black hole seeds would have formed directly from gas—we call them direct-collapse black holes (DCBHs). In the right environments, direct-collapse black holes could have been born at 104 or 105 solar masses within a few hundred million years after the Big Bang.
“With this head start, they could have easily grown to 109 or 1010 solar masses, thereby producing the ancient quasars that have puzzled astronomers for two decades.”
More Evidence Needed
Dr. Natarajan’s theory about direct-collapse black holes remains a theory for the time being. NASA’s James Webb Space Telescope, originally slated to launch in 2019, has been pushed back to 2021—but when it launches it will help scientists prove or disprove the existence of DCBHs. But how?
“To find out, we must search for observational evidence,” she said. “These objects would appear as bright, miniature quasars shining through the early universe. They should be detectable during a special phase when the seed merges with the parent galaxy—and this process should be common, given that DCBHs probably form in satellites orbiting larger galaxies.”
She said that this makes the perfect environment for a black hole seed to feed on plenty of gases, ensuring that the black hole grows at a rapid rate. It should, briefly, even turn the black hole itself into a special kind of quasar that would “outshine all the stars in the galaxy.”
For more of Dr. Natarajan’s article on the earliest black holes, as well as visual aids, check out The Great Courses’ Mind-Blowing Galaxies.