Seeing Double: Scientists Find Elusive Giant Black Hole Pairs
Astronomers have identified a bumper crop of dual supermassive black holes in the centers of galaxies. This discovery could help astronomers better understand how giant black holes grow and how they may produce the strongest gravitational wave signals in the Universe.
The new evidence reveals five pairs of supermassive black holes, each containing millions of times the mass of the Sun. These black hole couples formed when two galaxies collided and merged with each other, forcing their supermassive black holes close together….
The original journal article can be found here (Buried AGN in Advanced Mergers: Mid-infrared Color Selection as a Dual AGN Finder, S. Satyapal 2017, The Astrophysical Journal, 848, 126)
The Search for Seeds of Black Holes
How do you grow a supermassive black hole that is a million to a billion times the mass of our sun? Astronomers do not know the answer, but a new study using data from NASA’s Wide-field Infrared Survey Explorer, or WISE, has turned up what might be the cosmic seeds from which a black hole will sprout. The results are helping scientists piece together the evolution of supermassive black holes — powerful objects that dominate the hearts of all galaxies….
The original journal article can be found here [Discovery of a Population of Bulgeless Galaxies with Extremely Red Mid-IR Colors: Obscured AGN Activity in the Low-mass Regime? Satyapal, S. et al. 2014 ApJ 784 113].
NGC 4178: Revealing a Mini- Supermassive Black Hole
One of the lowest mass supermassive black holes ever observed in the middle of a galaxy has been identified, thanks to NASA’s Chandra X-ray Observatory and several other observatories. The host galaxy is of a type not expected to harbor supermassive black holes, suggesting that this black hole, while related to its supermassive cousins, may have a different origin….
The original journal article can be found here [A Multi-wavelength Analysis of NGC 4178: A Bulgeless Galaxy with an Active Galactic Nucleus. Secrest, N. et al. 2013 ApJ
Even Thin Galaxies Can Grow Fat Black Holes
NASA’s Spitzer Space Telescope has detected plump black holes where least expected: skinny galaxies. Like people, galaxies come in different shapes and sizes. There are thin spirals both with and without central bulges of stars, and more rotund ellipticals that are themselves like giant bulges. Scientists have long held that all galaxies except the slender, bulgeless spirals harbor supermassive black holes at their cores. Furthermore, bulges were thought to be required for black holes to grow.
The new Spitzer observations throw this theory into question. The infrared telescope surveyed 32 flat and bulgeless galaxies and detected monstrous black holes lurking in the bellies of seven of them. The results imply that galaxy bulges are not necessary for black hole growth; instead, a mysterious invisible substance in galaxies called dark matter could play a role.