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 777 139].
Black Hole Missing Link Found?
As far as we know, every galaxy that has a central bulge of old stars harbors a monster in its core: a supermassive black hole with anywhere from a million to 20 billion times the mass of the Sun. However, younger, bulge-less galaxies don’t have them. So, astronomers are scouting these for smaller, still-growing black holes — the missing links between the little black holes that form from collapsing stars and the monsters in galaxy cores.
See more at: Sky and Telescope.
The original journal article can be found here [A Chandra View of NGC 3621: A Bulgeless Galaxy Hosting an AGN in Its Early Phase? Gliozzi, M. et al. 2009 ApJ 700 1759].
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.
Student Helps Map Out the Sky with New Galaxy Discovery
“Not many undergraduate students can say that they’ve observed data on the world’s largest radio telescope. Even fewer can say that they themselves discovered a brand-new galaxy. Mason junior Lisa Horne has both those accomplishments under her belt…” Continue reading here.