On merger bias and the clustering of quasars

Abstract

We use the large catalogues of haloes available for the Millennium Simulation to test whether recently merged haloes exhibit stronger large-scale clustering than other haloes of the same mass. This effect could help us to understand the very strong clustering of quasars at high redshift. However, we find no statistically significant excess bias for recently merged haloes over the redshift range 2 ≤ z ≤ 5, with the most massive haloes showing an excess of at most ~5 per cent.We also consider galaxies extracted from a semi-analytic model built on the Millennium Simulation. At fixed stellar mass, we find an excess bias of 20-30 per cent for recently merged objects, decreasing with increasing st..