Institute of Astronomy

The Merger Times of High Redshift Dark Matter Halos

SpeakerTalk DateTalk Series
Thomas McCavana (Sydney)25 August 2010Institute of Astronomy Seminars

Abstract

Dynamical friction is thought to have a significant influence on the merger times for Dark Matter Halos(DMHs) and galaxies alike. Approximations of DMH merger times are often used in semi-analytical methods to estimate important quantities such as gas abundances, AGN activation rates as well as black hole binary formation and merger rates. Recent works have sought to tighten approximations of DMH merger times through both numerical and analytical approaches. In our work we use a high resolution (mass resolution of 705,000 solar masses) cosmological n-body simulation to measure the merger times for DMH mergers between redshifts z=10 to z=1. We follow the satellite haloes particles checking for bound subsets in subsequent snapshots. We find mergers that begin at high redshifts finish faster then those starting at low redshifts. Halo potentials at high redshifts are to some extent dynamic, constantly growing and changing via accretion, mergers and tidal interactions.

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