Astronomers have discovered a record number of hidden black holes, with about 35% of supermassive black holes in the universe obscured by gas and dust, according to a new study published in The Astrophysical Journal. This is significantly more than previously thought, with previous studies suggesting only about 15% were obscured.
The research, led by scientists at the University of Southampton, utilized data from NASA's NuSTAR (Nuclear Spectroscopic Telescope Array) and IRAS (Infrared Astronomical Satellite) missions. IRAS, launched in 1983, detected infrared radiation emitted from the accretion disks surrounding black holes, revealing their presence even when they are hidden from view in visible light.
The study focused on a sample of hundreds of supermassive black holes, confirming the presence of previously undetected black holes by analyzing their X-ray emissions. NuSTAR, with its high-energy X-ray vision, was able to penetrate the obscuring gas and dust, allowing scientists to directly observe the X-rays emitted by the black holes.
Poshak Gandhi, an astrophysicist at the University of Southampton and lead author of the study, commented on the significance of the discovery: "Black holes are fundamental to the evolution of galaxies, but they are often hidden from view. This study shows that there are many more hidden black holes than we previously thought, which has significant implications for our understanding of the universe."