Halo Substructure and the Power Spectrum

By A. Zentner, James S. Bullock. 2002

361 citations recorded by the source corpus.

We present a semianalytic model to investigate the merger history, destruction rate, and survival probability of substructure in hierarchically formed dark matter halos and use it to study the substructure content of halos as a function of input primordial power spectrum. For a standard cold dark matter "concordance" cosmology (ΛCDM; n = 1, σ8 = 0.95) we successfully reproduce the subhalo velocity function and radial distribution profile seen in N-body simulations and determine that the rate of merging and disruption peaks ~10-12 Gyr in the past for Milky Way-like halos, while surviving substructures are typically accreted within the last ~0-8 Gyr. We explore power spectra with normalizations and spectral "tilts" spanning the ranges σ8 ≃ 1-0.65 and n ≃ 1-0.8, and include a "running-index" model with dn/d ln k = -0.03 similar to the best-fit model discussed in the first-year Wilkinson Microwave Anisotropy Probe (WMAP) report. We investigate spectra with truncated small-scale power, including a broken-scale inflation model and three warm dark matter cases with mW = 0.75-3.0 keV. We find that the mass fraction in substructure is relatively insensitive to the tilt and overall normalization of the primordial power spectrum. All of the CDM-type models yield projected substructure mass fractions that are consistent with, but on the low side, of published estimates from strong lens systems: f9 = 0.4%-1.5% (64th percentile) for subhalos smaller than 109 M☉ within projected cylinders of radius r < 10 kpc. Truncated models produce significantly smaller fractions, f9 = 0.02%-0.2% for mW ≃ 1 keV, and are disfavored by lensing estimates. This suggests that lensing and similar probes can provide a robust test of the CDM paradigm and a powerful constraint on broken-scale inflation/warm particle masses, including masses larger than the ~1 keV upper limits of previous studies. We compare our predicted subhalo velocity functions with the dwarf satellite population of the Milky Way. Assuming that dwarfs have isotropic velocity dispersions, we find that the standard n = 1 model overpredicts the number of Milky Way satellites at Vmax ≲ 35 km s-1, as expected. Models with less small-scale power do better because subhalos are less concentrated and the mapping between observed velocity dispersion and halo Vmax is significantly altered. The running-index model, or a fixed tilt with σ8 ~ 0.75, can account for the local dwarfs without the need for differential feedback (for Vmax ≳ 20 km s-1); however, these comparisons depend sensitively on the assumption of isotropic velocities in satellite galaxies.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/f15d160b214623603e326759a1cd1ba7ff9cffc9

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Citations in the corpus

The Great disk of Milky Way satellites and cosmological sub-structures (2004, background): “The theoretical sub-structure distribution of MW-type hosts must therefore be essentially isotropic (Ghigna et al. 1998; Zentner & Bullock 2003; Diemand et al. 2004; Kravtsov et al. 2004; Aubert et al. 2004).”
Λ Cold Dark Matter, Stellar Feedback, and the Galactic Halo Abundance Pattern (2005, background): “For Milky-Way size halos in the standardΛCDM model, the accretion rate of dwarf-galaxy halos peaks∼ 10 Gyr in the past, and slows down considerably at a look-back time of∼ 8 Gyr, although there is scatter from halo to halo (Zentner & Bullock 2003).”
BARYONS MATTER: WHY LUMINOUS SATELLITE GALAXIES HAVE REDUCED CENTRAL MASSES (2012, background): “The infall times are listed in Table 1, and in all cases the infall redshift is at z < 3 (see also Zentner & Bullock 2003; Geen et al. 2012).”
The Most Dark-Matter-dominated Galaxies: Predicted Gamma-Ray Signals from the Faintest Milky Way Dwarfs (2007, result): “This is a similar result to those obtained in semianalytic models of many realizations of the subhalo population (Zentner & Bullock 2003; van den Bosch et al. 2005).”
Characterizing the Cluster Lens Population (2005, background): “In addition, Zentner & Bullock (2003) found that the degree of substructure in dark matter halos anti-correlates with concentration, and we have seen that more centrally concentrated clusters tend to dominate the lensing cross section.”
Sweating the small stuff: simulating dwarf galaxies, ultra-faint dwarf galaxies, and their own tiny satellites (2015, background): “If ΛCDM is correct, then all dark matter halos hosting galaxies – from those hosting dwarfs to those hosting giant clusters – should be filled with substructure (Moore et al. 1999; Klypin et al. 1999; Zentner & Bullock 2003).”
Too big to fail in the Local Group (2014, background): “Sample Afit A+68 per cent A−68 per cent Isolated 0.747 1.09 0.521 Paired 0.704 1.00 0.499 Combined 0.725 1.06 0.511 offset in σ 8 (Zentner & Bullock 2003; Polisensky & Ricotti 2014).”
THE KILOPARSEC-SCALE KINEMATICS OF HIGH-REDSHIFT STAR-FORMING GALAXIES (2009, background): “Such lumps can disrupt the preferred kinematic axis of disk galaxies in the local universe (e.g., Benson et al. 2004), and their effects would likely be stronger at higher redshifts when dark matter haloes were merging more rapidly (e.g., Zentner & Bullock 2003; Fakhouri & Ma 2008).”
The Dependence of Halo Clustering on Halo Formation History, Concentration, and Occupation (2005, background): “…halos that accrete their subhalos first have more time for those subhalos to be destroyed or to merge with the central object due to dynamical friction (e.g., Kravtsov &Klypin 1999; Taffoni et al. 2003; Zentner & Bullock 2003; Zentner et al. 2005; van den Bosch et al. 2005; Taylor & Babul 2005).”
CHEMICAL EVOLUTION IN HIERARCHICAL MODELS OF COSMIC STRUCTURE. II. THE FORMATION OF THE MILKY WAY STELLAR HALO AND THE DISTRIBUTION OF THE OLDEST STARS (2009, background): “Basics Dark-matter only simulation of cosmic structure is by now a mature technique that has generated many useful insights into the dynamical assembly of the Galaxy’s dark-matter halo (Helmi et al. 2003) and its satellites (Zentner & Bullock 2003; Kravtsov et al. 2004).”
Luminosity function and radial distribution of Milky Way satellites in a ΛCDM Universe (2009, methodology): “…central galaxy of the larger halo as “satellites”. c© 0000 RAS, MNRAS 000, 000–000 when their stripped mass drops below the mass contained within a fixed fraction of the halo’s original NFW (Navarro, Frenk and White 1997) scale radius rs (following Zentner & Bullock 2003 and Taylor & Babul 2004).”
GLOBULAR CLUSTERS IN THE OUTER GALACTIC HALO: NEW HUBBLE SPACE TELESCOPE/ADVANCED CAMERA FOR SURVEYS IMAGING OF SIX GLOBULAR CLUSTERS AND THE GALACTIC GLOBULAR CLUSTER AGE–METALLICITY RELATION (2011, methodology): “…akin to the fragmentation and accretion scenario advocated by Searle & Zinn (1978, see also Navarro et al. 1997) and featured in models of galaxy formation based on the cold dark matter paradigm with a cosmological constant (e.g., Zentner & Bullock 2003; Robertson et al. 2005; Font et al. 2006).”
Redefining the Missing Satellites Problem (2007, background): “…on the collapse time and orbital evolution of each system, the precise Vmax-rmax relation is sen- sitive to cosmology (e.g. σ8) and the formation history of the host halo itself (e.g. Zentner & Bullock 2003; Power 2003; Kazantzidis et al. 2004; Bullock & Johnston 2005; Bullock & Johnston 2006).”
The Time Delays of Gravitational Lens HE 0435–1223: An Early-Type Galaxy with a Rising Rotation Curve (2005, background): “%) exists in clumps, which are sometimes referred to as CDM satellites or substructures (e.g., Kauffmann et al. 1993; Moore et al. 1999; Klypin et al. 1999; Bode et al. 2001; Zentner & Bullock 2003).”
Tests for Substructure in Gravitational Lenses (2003, background): “…that the incidence of anomalous flux ratios in gravitational lenses was consistent with the expected mass fraction of satellites found in cold dark matter (CDM) halo simulations (e.g., Kauffmann et al. 1993; Moore et al. 1999; Klypin et al. 1999; Bode et al. 2001; Zentner & Bullock 2003).”