Velocity and spatial biases in cold dark matter subhalo distributions

By J. Diemand, B. Moore, Joachim Stadel. 2004

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We present a statistical study of substructure within a sample ofCDM clusters and galaxies simulated with up to 25 million particles. With thousands of subhalos per object we can accurately measure their spatial clustering and velocity distribution functions and compare these with observational data. The substructure properties of galactic halos closely resembles those of galaxy clusters with a small scatter in the mass and circular velocity functions. The velocity distribution function is non-Maxwellian and flat topped with a negative kurtosis of about -0.7. Within the virial radius the velocity bias b = σsub/σDM � 1.12±0.04, increasing to b > 1.3 within the halo centers. Slow subhalos are much less common, due to physical disruption by gravitational tides early in the merging history. This leads to a spatially anti-biased subhalo distribution that is well fitted by a cored isothermal. Observations of cluster galaxies do not show such biases which we interpret as a limitation of pure dark matter simulations - we estimate that we are missing half of the halo population which has been destroyed by physical overmerging. High resolution hydrodynamical simulations are required to study these issues further. If CDM is correct then the cluster galaxies must survive the tidal field, perhaps due to baryonic inflow during elliptical galaxy formation. Spirals can never exist near the cluster centers and the elliptical galaxies there will have little remaining dark matter. This implies that the morphology-density relation is set before the cluster forms, rather than a subsequent transformation of disks to S0's by virtue of the cluster environment.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/151e94dcd5e80d95f928b5a00a6df12f926d17ae

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Citations in the corpus

Substructures in hydrodynamical cluster simulations (2008, background): “…matter (DM) only simulations, a consistent picture of the population of subhalos within galaxy clusters has now emerged (e.g., Moore et al. 1999; Ghigna et al. 2000; Springel et al. 2001; Stoehr et al. 2002, 2003; Diemand et al. 2004; Gao et al. 2004; De Lucia et al. 2004; Kravtsov et al. 2004).”
What determines satellite galaxy disruption (2009, methodology): “However, this method leads to satellite subhalos with significantly less concentrated radial distributions than seen for satellite galaxies around the Milky Way (Kravtsov et al. 2004) or galaxy clusters (Diemand et al. 2004).”
MEASURING THE ULTIMATE HALO MASS OF GALAXY CLUSTERS: REDSHIFTS AND MASS PROFILES FROM THE HECTOSPEC CLUSTER SURVEY (HeCS) (2012, background): “Indeed, simulations suggest that little or no velocity bias exists on linear and mildly non-linear scales (Kauffmann et al. 1999a,b; Diemand et al. 2004; Faltenbacher et al. 2005).”
The Physics of Galaxy Clustering. I. A Model for Subhalo Populations (2004, background): “Recently, Gao et al. (2004a) reported the measurement of a deviation from the self-similar scaling of subhalo populations in simulated halos (Diemand et al. 2004, hinted at this but did not have a large enough host halo sample to make a significant detection) while van den Bosch et al. (2004b)…”
The relation between velocity dispersion and mass in simulated clusters of galaxies: dependence on the tracer and the baryonic physics (2013, background): “The other process is tidal disruption, caused by the integral of tidal interactions leading to mass losses (e.g. Diemand et al. 2004).”
CIRS: Cluster Infall Regions in the Sloan Digital Sky Survey. I. Infall Patterns and Mass Profiles (2006, background): “%) or no velocity bias exists on linear and mildly non-linear scales (Kauffmann et al. 1999a,b; Diemand et al. 2004; Faltenbacher et al. 2005).”
THE UNORTHODOX ORBITS OF SUBSTRUCTURE HALOS (2008, result): “This is in agreement with the earlier results of Gao et al (2004) and Diemand et al (2004), but indicates that the apparent mass-independence of the subhalo spatial distribution is not the result of efficient mixing within the main halo, but rather a somewhat fortuitous result of the cancellation…”
Thin, thick and dark discs in ΛCDM (2008, background): “We find α = 3 gives a better formal fit in agreement with Diemand et al. 2004.)”
Globular clusters, satellite galaxies and stellar haloes from early dark matter peaks (2005, background): “…halo and those who lie near the centre at z = 0 move faster (both in the tangential and radial directions) than the dark matter particles, that is, these inner subhaloes have large orbital energies and spend most of their time further away from the centre (Figs 4–6, see also Diemand et al. 2004).”
The Phoenix Project: the dark side of rich galaxy clusters (2012, background): “…the highest-resolution galaxy cluster simulations published to date have at most of order af w million particles within the virial radius (e.g. Jing & Suto2000; Springel et al. 2001a; Diemand et al. 2004a; Reed et al. 2005), roughly one thousand times fewer than the best resolved Aquar- ius halo.”
Hundreds of Milky Way Satellites? Luminosity Bias in the Satellite Luminosity Function (2008, background): “Previous studies have pointed to discrepancies between simulations and observations of other galaxies’ satellite distributions (e.g., Diemand et al. 2004; Chen et al. 2006).”
Modeling Luminosity-dependent Galaxy Clustering through Cosmic Time (2005, background): “…approach is that subhalos selected using the present-day mass or circular velocity tend to have radial distributions within their larger distinct halos that are shallower than those exhibited by observed galaxies (Gao et al. 2004; Diemand et al. 2004; Nagai & Kravtsov 2005; Macció et al. 2005).”
Semianalytical Model of Galaxy Formation with High-Resolution N-Body Simulations (2004, background): “…parameters are very similar to those adopted in many high-resolution resimulations of individual cluster halos (Moore et al. 1999; Jing & Suto 2000; Fukushige & Makino 2001, 2003; Power et al. 2003; Diemand et al. 2004), we have achieved a resolution that can resolve subhalos within massive halos.”