Concentrations of Dark Halos from Their Assembly Histories

By Risa Wechsler, James S. Bullock, Joel R. Primack, Andrey V. Kravtsov, A. Dekel. 2001

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We study the relation between the density profiles of dark matter halos and their mass assembly histories using a statistical sample of halos in a high-resolution N-body simulation of the ΛCDM cosmology. For each halo at z = 0, we identify its merger history tree and determine concentration parameters cvir for all progenitors, thus providing a structural merger tree for each halo. We fit the mass accretion histories by a universal function with one parameter, the formation epoch ac, defined when the log mass accretion rate d log M/d log a falls below a critical value S. We find that late-forming galaxies tend to be less concentrated, such that cvir "observed" at any epoch ao is strongly correlated with ac via cvir = c1ao/ac. Scatter about this relation is mostly due to measurement errors in cvir and ac, implying that the actual spread in cvir for halos of a given mass can be mostly attributed to scatter in ac. We demonstrate that this relation can also be used to predict the mass and redshift dependence of cvir and the scatter about the median cvir(M, z) using accretion histories derived from the extended Press-Schechter (EPS) formalism, after adjusting for a constant offset between the formation times as predicted by EPS and as measured in the simulations; this new ingredient can thus be easily incorporated into semianalytic models of galaxy formation. The correlation found between halo concentration and mass accretion rate suggests a physical interpretation: for high mass infall rates, the central density is related to the background density; when the mass infall rate slows, the central density stays approximately constant, and the halo concentration just grows as Rvir. Because of the direct connection between halo concentration and velocity rotation curves and because of probable connections between halo mass assembly history and star formation history, the tight correlation between these properties provides an essential new ingredient for galaxy formation modeling.

Subfields: Astronomy and Astrophysics, Global and Planetary Change, Instrumentation

View Paper: https://www.semanticscholar.org/paper/013464f012cc77fedc44e6bbbaa729ff08ca5a5e

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Citations in the corpus

EVOLUTION OF THE GALAXY–DARK MATTER CONNECTION AND THE ASSEMBLY OF GALAXIES IN DARK MATTER HALOS (2011, background): “In general, more massive halos assemble later than smaller ones, which reflects the hierarchical nature of structure formation in the CDM model (e.g., van den Bosch 2002; Wechsler et al. 2002).”
Mass accretion rates and histories of dark matter haloes (2009, background): “For the 1-parameter exponential form (e.g. Wechsler et al. 2002) M(z) = M0e −αz, (1) the parameter α is simply related to zf by zf = ln(2) α .”
Self-Interacting Dark Matter from a Non-Abelian Hidden Sector (2014, background): “[34] R.”
A UNIVERSAL MODEL FOR HALO CONCENTRATIONS (2014, methodology): “As shown in previous studies, the mass dependence of the concentration of halos is a consequence of their MAH (Wechsler et al. 2002; Zhao et al. 2003b, 2009; Ludlow et al. 2013), which, in turn, is determined by the parameters of the background cosmological model.”
NGC 3741: the dark halo profile from the most extended rotation curve (2006, background): “The recent third year WMAP (Wilkinson Microwave Anisotropy Probe) results (Spergel et al. 2006) suggest, however, that the concentration parameters predicted by Bullock et al. (2001) and Wechsler et al. (2002) should be lower, in particular due to the lower σ 8.”
Luminosity function and radial distribution of Milky Way satellites in a ΛCDM Universe (2009, methodology): “We use the two criteria suggested in Wechsler et al. (2002) for halo 1 at one output time to be labeled a “progenitor” of halo 2 at the subsequent output time.”
The Stellar Mass Tully-Fisher Relation to z = 1.2 from AEGIS (2006, background): “In addition, neither the halo σs−Ms relation, nor Ms or σs individually, is predicted to evolve to within ∼ 10% from z = 1.2 to now (Diemand et al. 2007; see Wechsler et al. 2002 for evolution in terms of virial quantities).”
The Physics of Galaxy Clustering. I. A Model for Subhalo Populations (2004, background): “The concentrations of dark matter halos observed in simulations are tightly correlated with their mass accretion histories (Wechsler et al. 2002, hereafter W02; Zhao et al. 2003).”
Dwarf galaxies in voids: suppressing star formation with photoheating (2005, background): “Wechsler et al. (2002) and van den Bosch (2002) showed that the average dark matter mass accretion histories can be approximated by MMAH(z) = Mtot(z = 0) e −αz, (23) which works especially well for halos with an early formation time.”
The First Cosmic Structures and Their Effects (2004, background): “On the other hand, recent simulations which accurately follow the mass accretion histories of dark matter halos (Wechsler et al. 2002; Zhao, Jing & Boerner 2003), find an early phase of fast accretion, during which the inner structure of halos is mainly built, followed by a late phase of gentle…”
Formation and Evolution of Galaxy Dark Matter Halos and Their Substructure (2007, methodology): “Many of the existing definitions are based on the evolution of M200 or Mvir (e.g. Wechsler et al. 2002; Zhao et al. 2003; Gao et al. 2005).”
Statistics of Physical Properties of Dark Matter Clusters (2005, background): “It is also thought that the dispersion in concentrations is related to the dispersion of halo formation epochs (Wechsler et al. 2002).”
Toy models for galaxy formation versus simulations (2013, background): “(9) This functional form was indeed found to be a good fit to the halo growth in earlier cosmological N -body simulations of lower resolution (Wechsler et al. 2002; Neistein & Dekel 2008b).”
Galacticus: A Semi-Analytic Model of Galaxy Formation (2010, methodology): “s smooth accretion and branches are truncated once they fall below this mass. Smooth Accretion: This method builds a branchless merger tree with a smooth accretion history using the ﬁtting formula of Wechsler et al. (2002). The tree is deﬁned by a ﬁnal mass at a speciﬁed redshift and is continued ba”
The radial velocity dispersion profile of the Galactic halo : constraining the density profile of the dark halo of the Milky Way (2005, background): “The concentration c has been found to correlate with the virial mass of the halo (Navarro, Frenk & White 1997; Bullock et al. 2001; Wechsler et al. 2002).”
The Dark Side of the Halo Occupation Distribution (2003, methodology): “This simulation was also used to study halo concentrations (Bullock et al. 2001b), the specific angular momentum distribution (Bullock et al. 2001a), and the accretion history of halos (Wechsler et al. 2002).”
Generating dark matter halo merger trees (2007, background): “That the EPS theory gives predictions that evolve more rapidly with redshift than is found in N-body simulations has been noted previously (e.g van den Bosch 2002; Wechsler et al. 2002; Lin et al. 2003).”