NASA Astronomers Zero In on the Number of Hidden Supermassive Black Holes

There are probably more supermassive black holes lurking in the universe than we can see, according to a team of scientists who have just established a new estimate for the number of giants hidden from view.

The discovery could help scientists understand how supermassive black holes get so big — billions of times the mass of our Sun — and clarify the crucial role black holes play in galactic evolution.

Black holes have such intense gravitational fields that not even light can escape their proximity behind a certain point – the black hole’s event horizon. But beyond the event horizon, the surrounding environment of the black hole is extremely bright, as it is crowded with a pancake of superheated gas and dust known as an accretion disk.

That material sometimes blocks the light that astronomical observers would otherwise see. The team found that about 35% of the supermassive black holes they studied are obscured by the surrounding gas and dust. This discovery indicates that the number of hidden black holes is greater than previously thought, as previous research indicated that about 15% of supermassive black holes were so obscured. The team’s research was published last month in The Astrophysical Journal.

The team reached their conclusions based on data from NASA’s Infrared Astronomical Satellite (IRAS) and the Nuclear Spectroscopic Telescope Observatory’s (NuSTAR) X-ray observatory. IRAS picks up infrared light (as its name suggests), and infrared emissions from black hole accretion disks reveal whether it is directly at the satellite, or whether its edge is pointed towards the instrument. After identifying a group of hundreds of initial targets with IRAS, the research team used NuSTAR to confirm the edge-on—that is, obscured—black holes based on their X-ray emissions.

“If we didn’t have black holes, galaxies would be much bigger,” said study co-author Poshak Gandhi, an astrophysicist at the University of Southampton at NASA’s Jet Propulsion Laboratory. liberation. “So, if we don’t have a supermassive black hole in our Milky Way galaxy, there could be many more stars in the sky. It’s just an example of how black holes can influence the evolution of a galaxy.”

Furthermore, the influence of black holes can extend far beyond the galaxies in which they reside. Last year, a team of astrophysicists identified the the largest jets of black holes known– streams of particles emerging from the object at almost the speed of light. The jets are called Porphyrion, after a giant from Greek mythology, and are at least 140 times longer than the Milky Way galaxy is wide.

Black holes are crucial drivers of galactic evolution, but even these extremely massive objects can evade human detection. Recent research has shown how these hidden black holes stay out of sight – and indicate that there are even more of the cosmic juggernauts than we know.