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M. Milosavljevic (Rutgers University)
The evolution of central density profiles of galaxies and cold dark matter (CDM) halos is studied in the hierarchical merging scenario of structure formation. We have carried out large scale N-body simulations of successive mergers of both types of objects in the presence of massive black holes. We study the effects of each generation of mergers on the concentration of matter in the inner kiloparsec. Successive mergers have been found to induce cumulative damage on cusps composed of stars and/or CDM particles. To quantify the suppression of steep density cusps we define the notion of mass deficit that can be used to compare simulations with the observation. The stellar mass deficits of early type galaxies are found to be a few times larger than the masses of their central black holes over two decades in black hole mass. This can be interpreted as evidence for the formation of galaxy nuclei by hierarchical merging of protogalactic fragments. We calculate the damage incurred by the CDM cusps during hierarchical merging and provide upper limits on the densities of galaxy-size dark matter halos.
The author(s) of this abstract have provided an email address for comments about the abstract: milos@physics.rutgers.edu