Secular Growth of Galaxies and Supermassive Black Holes

Brooke Simmons (University of Oxford)

We have recently identified and analyzed a population of galaxies which have grown to large sizes (M* ~ 10^10 Msun) despite calm formation histories free of both significant mergers and violent non-merger processes, evidenced by their lack of classical bulges and extremely small (or non-existent) pseudobulges. Yet each galaxy in the sample also has a growing supermassive black hole, and our analysis strongly suggests the black holes have grown substantially, to typical black hole masses for bulge-dominated and elliptical galaxies of these stellar masses. Interestingly, the galaxies and black holes appear to obey the same black hole-galaxy mass relation as that empirically determined based on galaxies with histories including major mergers. This implies that the co-evolution of black holes and galaxies may proceed independently of the details of the dynamical evolution of the host galaxy. This talk will discuss these results in the context of a more general study indicating bulgeless galaxies are not as rare as previously thought, indicating that secular growth plays a significant role in the evolution of most galaxies.

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