The Fate of Dwarf Galaxies in Clusters and the Origin of Intracluster Stars. Ii. Cosmological Simulations

Abstract

We combine a N-body simulation algorithm with a subgrid treatment of galaxy formation, mergers, and tidal destruction, and an observed conditional luminosity function Φ(L|M ), to study the origin and evolution of galactic and extragalactic light inside a cosmological volume of size (100 Mpc) 3 , in a concordance ΛCDM model. This algorithm simulates the growth of large-scale structures and the formation of clusters, the evolution of the galaxy population in clusters, the destruction of galaxies by mergers and tides, and the evolution of the intracluster light. We find that destruction of galaxies by mergers dominates over destruction by tides by about an order of magnitude at all redshifts. However, tidal destruction is sufficient to produce intracluster light fractions f ICL that are sufficiently high to match observations. Our simulation produces 18 massive clusters (M cl > 10 14 M ⊙ ) with values of f ICL ranging from 1% to 58% at z = 0. There is a weak trend of f ICL to increase with cluster mass. The bulk of the intracluster light (∼ 60%) is provided by intermediate galaxies of total masses 10 11 M ⊙ − 10 12 M ⊙ and stellar masses 6× 10 8 M ⊙ − 3× 10 10 M ⊙ that were tidally destroyed by even more massive galaxies. The contribution of low-mass galaxies to the intracluster light is small and the contribution of dwarf galaxies is negligible, even though, by numbers, most galaxies that are tidally destroyed are dwarfs. Tracking clusters back in time, we find that their values of f ICL tend to increase over time, but can experience sudden changes that are sometimes non-monotonic. These changes occur during major mergers involving clusters of comparable masses but very different intracluster luminosities. Most of the tidal destruction events take place in the central regions of clusters. As a result, the intracluster light is more centrally concentrated than the galactic light. Our results support tidal destruction of intermediate-mass galaxies as a plausible scenario for the origin of the intracluster light.

The Fate of Gas-rich Satellites in Clusters

“…On the other hand, Murante et al (2007) suggested that the merging events prior to the formation of the cluster are the main contributor to the ICL. Through a set of cosmological simulations, Martel et al (2012) concluded that destruction of galaxies by mergers dominates over the tidal stripping by about an order of magnitude at all redshifts. In these simulations, the bulk of the ICL was made by intermediate size satellites with halo mass in the range of 10 11 − 10 12 M .…”

Probing Dark Matter Subhalos in Galaxy Clusters Using Highly Magnified Stars

“…The projected surface density of intracluster stars near critical curves, typically ∼ 50 kpc from the cluster center, usually contributes a lensing convergence κ 10 −3 -10 −2 (Zwicky 1951;Lin & Mohr 2004;Zibetti et al 2005). These stars may have been tidally stripped from cluster galaxies throughout the assembly history of the brightest central galaxy (BCG), or have formed in situ within tidally ejected intracluster clouds (Martel et al 2012;Contini et al 2014;Cooper et al 2015). Despite these low values of κ , a similar line of reasoning as that in Eqs.…”

The environmental dependence of the stellar mass function atz~ 1

“…van Dokkum et al 1999), and that the intra-cluster light builds up over time, probably by disruptions of relatively low mass galaxies (Martel et al 2012). Also we know that BCGs have to grow in stellar mass over time (e.g.…”