Supermassive black hole discovery shatters records
Black holes massive enough to power quasars, some of the brightest objects in the universe, have been discovered for the first time in the "nearby" galaxy.
One of the supermassive black holes is 9.7 billion times larger than our sun, and the other is at least as massive, if not more massive, Canadian and U.S. scientists report in a study published online in the journal Nature on Monday.
That blows away the previous record mass for a supermassive black hole, 6.3 billion times the mass of the sun, which had been held by a black hole in a galaxy called Messier 87.
The black holes' colossal mass came as a surprise to the researchers themselves, as they were significantly higher than predicted based on the characteristics of the galaxies surrounding them. The researchers suggested that could mean the growth of the largest galaxies and their black holes may follow a different process than other galaxies.
Black holes are believed to be found at the centre of all galaxies, including our own Milky Way, and larger galaxies tend to have more massive black holes.
300 million light years away
The new black holes are located more than 300 million light years away in two giant elliptical galaxies called NGC 3842, located in the direction of the constellation Leo, and NGC 4889, in the direction of the constellation Coma Berenices.
"We believe that 10-billion solar mass black holes like these are the ultimate power sources for the distant quasars observed in the early universe, one to three billion years after the Big Bang," said study co-author James Graham, director of the Dunlap Institute for Astronomy and Astrophysics at the University of Toronto.
Quasars are extremely bright, star-like objects that can be seen by looking at the very distant reaches of the universe.
Because of the time it takes light to travel such long distances, the light that we see from distant objects left them and spent millions or billions of years travelling before reaching us. That means we see them as they were millions or billions of years ago.
Astrophysicists have long thought that quasars are powered by supermassive black holes. Based on the brightness of the quasars, they have estimated those black holes to have masses more than 10 billion times the mass of the sun. Up until now, comparable black holes had never been measured in the "nearby" universe.
New black holes 'may be the missing link'
The two new black holes, located relatively close to Earth, are similar in mass to young quasars, and "may be the missing link between quasars and the [smaller] supermassive black holes we see today," said Chung-Pei Ma, an astronomy professor at the University of California, Berkeley, who also co-authored the paper.
While the black holes are no longer associated with quasars, they are massive enough that they may have powered very bright quasars billions of years ago.
The researchers figured out the mass of the two newly discovered black holes by measuring the speed of stars orbiting their galaxies, using the Gemini, MacDonald and Keck Observatories — three Earth-based telescopes.
That provided information about the strength of the black holes' gravitational fields, which are in turn proportional to their masses.
"That's a very reliable way of measuring mass," said Graham in an interview. He noted there is a lot more uncertainty in the estimates of the masses of quasar-powering black holes in the distant universe.