Amy Reines (NRAO)

Probing the Early Evolution of Massive Black Holes with Dwarf Starburst Galaxies

Supermassive black holes are now thought to inhabit essentially all modern massive galaxies with bulges, yet the birth and early evolution of the first high-redshift seed black holes is poorly constrained. Reines et al. (2011) have recently identified a million-solar mass black hole in the vigorously star-forming, bulgeless dwarf galaxy Henize 2-10. This discovery offers the first opportunity to study a growing black hole in a nearby galaxy much like those in the earlier universe, and opens up an entirely new class of host galaxies in which to search for local analogues of primordial black hole growth. Moreover, this finding has important implications for our understanding of the co-evolution of galaxies and their central black holes. In particular, the lack of a discernible bulge in Henize 2-10 indicates that black hole growth can precede the build-up of galaxy spheroids, which has been a subject of debate in the community. It is clearly important to search for other examples of massive black holes in dwarf starburst galaxies to begin to characterize them as a population, and improve the current understanding of the early stages of supermassive black hole growth.