The Lives of High Redshift Mergers

TL;DR

This paper compares merger timescales from idealized models and cosmological simulations, finding that cosmological models offer more accurate and versatile estimates for high-redshift dark matter mergers.

Contribution

It provides a detailed analysis of merger timescales in cosmological simulations, emphasizing the importance of cosmologically motivated formulas over idealized ones.

Findings

Jiang et al. (2008) formula fits cosmological merger data well

Cosmological merger-timescales are more robust for modeling

High-redshift mergers can be effectively characterized

Abstract

We present a comparative study of recent works on merger-timescales with dynamical friction and find a strong contrast between idealized/isolated mergers (Boylan-Kolchin et al. 2008) and mergers from a cosmological volume (Jiang et al. 2008). Our study measures the duration of mergers in a cosmological N-body simulation of dark matter, with emphasis on higher redshifts (z < 10) and a lower mass range. In our analysis we consider and compare two merger definitions; tidal disruption and coalescence. We find that the merger-time formula proposed by Jiang et al. (2008) describes our results well and conclude that cosmologically motivated merger-time formulae provide a more versatile and statistically robust approximation for practical applications such as semi-analytic/hybrid models.