Merger Histories of Galaxy Halos and Implications for Disk Survival

Understand

We study the merger histories of galaxy dark matter halos using a high resolution LCDM N-body simulation.

• Our merger trees follow ~17,000 halos with masses M_0 = (10^11--10^13) Msun at z=0 and track accretion events involving objects as small as m = 10^10 Msun.
• We find that mass assembly is remarkably self-similar in m/M_0, and dominated by mergers that are ~10% of the final halo mass.
• While very large mergers, m > 0.4 M_0, are quite rare, sizeable accretion events, m ~ 0.1 M_0, are common.