Modelling the dynamical friction timescale of sinking satellite

Abstract

When a satellite galaxy falls into a massive dark matter halo, it suffers the dynamical friction force which drag it into the halo center and finally it merger with the central galaxy. The time interval between entry and merger is called as the dynamical friction timescale (T_df). Many studies have been dedicated to derive T_df using analytical models or N-body simulations. These studies have obtained qualitative agreements on how T_df depends on the orbit parameters, and mass ratio between satellite and host halo. However, there are still disagreements on the accurate form of T_df . In this paper, we present a semi-analytical model to predict T_df and we focus on interpreting the discrepancies among different studies. We find that the treatment of mass loss from satellite by tidal stripping dominates the behavior of T_df . We also identify other model parameters which affect the predicted T_df.

13 pages, 7 figures, accepted for publication in Research in Astronomy and Astrophysics (RAA)

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• Lopsided Satellite Distributions around Isolated Host Galaxies in a LCDM Universe
• Chandrasekhar's Dynamical Friction and non-extensive statistics
• Extracting Galaxy Merger Timescales II: A new fitting formula
• The Distribution of Satellite Galaxies in the TNG100 Simulation