A calibration of the relation between the abundance of close galaxy pairs and the rate of galaxy mergers

Understand

Estimates of galaxy merger rates based on counts of close pairs typically assume that most of the observed systems will merge within a few hundred Myr (for projected pair separations <25 kpc/h).

• Here we investigate these assumptions using virtual galaxy catalogues derived from the Millennium Simulation, a very large N-body simulation of structure formation in the concordance LCDM cosmology.
• These catalogues have been shown to be at least roughly consistent with a wide range of properties of the observed galaxy population at both low and high redshift.
• Here we show that they also predict close pair abundances at low redshift which agree with those observed.