Milos Milosavljevic (UT Austin)

Growing Massive Black Holes at Cosmic Dawn

Massive black holes inhabit the centers of all but the smallest of galaxies. Billion solar mass black holes were present when the universe was at a tenth of its present age. How did such extreme objects emerge on the cosmic stage? Attempting to trace their evolution to the beginnings quickly leads to formidable theoretical challenges. Black holes produced in the standard stellar core collapse face particular obstacles to becoming massive. A head start in the prompt formation of a black hole already more massive than any star would have interesting theoretical and observational implications. I will discuss the radiatively-efficient and radiatively-inefficient avenues for the subsequent growth, and for the latter, I will attempt to gain insight from the empirically rich physics of the cosmic gamma-ray burst sources. Ultimately, however, a growing black hole competes with star formation in the host galaxy. It is thus worthwhile to study the structure and formation of dwarf galaxy nuclei. In the nearby universe they do not seem to contain massive black holes, but in the early universe dwarf galaxy nuclei should have been sites of massive black hole formation.