The scale-dependence of halo assembly bias

The two-point clustering of dark matter haloes is influenced by halo properties besides mass, a phenomenon referred to as halo assembly bias. Using the depth of the gravitational potential well, V-max, as our secondary halo property, in this paper, we present the first study of the scale-dependence of assembly bias. In the large-scale linear regime, r a parts per thousand yen 10 h(-1) Mpc, our findings are in keeping with previous results. In particular, at the low-mass end (< M-coll a parts per thousand 10(12.5) M-aS (TM) h(-1)), haloes with high V-max show stronger large-scale clustering relative to haloes with low V-max of the same mass; this trend weakens and reverses for M-vir a parts per thousand(3) M-coll. In the non-linear regime, assembly bias in low-mass haloes exhibits a pronounced scale-dependent 'bump' at 500 kpc h(-1)-5 Mpc h(-1). This feature weakens and eventually vanishes for haloes of higher mass. We show that this scale-dependent signature can primarily be attributed to a special subpopulation of ejected haloes, defined as present-day host haloes that were previously members of a higher mass halo at some point in their past history. A corollary of our results is that galaxy clustering on scales of r similar to 1-2 Mpc h(-1) can be impacted by up to similar to 15 per cent by the choice of the halo property used in the halo model, even for stellar mass-limited samples.