Environmental effect on the subhalo abundance -- a solution to the missing dwarf problem

Abstract

Recent high-resolution simulations of the formation of dark-matter halos have shown that the distribution of subhalos is scale-free, in the sense that if scaled by the velocity dispersion of the parent halo, the velocity distribution function of galaxy-sized and cluster-sized halos are identical. For cluster-sized halos, simulation results agreed well with observations. Simulations, however, predicted far too many subhalos for galaxy-sized halos. Our galaxy has several tens of known dwarf galaxies. On the other hands, simulated dark-matter halos contain thousands of subhalos. We have performed simulation of a single large volume and measured the abundance of subhalos in all massive halos. We found that the variation of the subhalo abundance is very large, and those with largest number of subhalos correspond to simulated halos in previous studies. The subhalo abundance depends strongly on the local density of the background. Halos in high-density regions contain large number of subhalos. Our galaxy is in the low-density region. For our simulated halos in low-density regions, the number of subhalos is within a factor of three to that of our galaxy. We argue that the ``missing dwarf problem'' is not a real problem but caused by the biased selection of the initial conditions in previous studies, which were not appropriate for field galaxies.

8 pages, 5 figures, higher resolution run added, accepted by PASJ

Cited by in corpus (14)

• The Aquarius Project: the subhalos of galactic halos
• The Substructure Hierarchy in Dark Matter Haloes
• Internal properties and environments of dark matter halos
• Disentangling galaxy environment and host halo mass
• The Cosmogrid Simulation: Statistical Properties of Small Dark Matter Halos
• Milky Way mass constraints from the Galactic satellite gap
• Phantom-GRAPE: numerical software library to accelerate collisionless $N$-body simulation with SIMD instruction set on x86 architecture
• Gravitational lensing as a probe of cold dark matter subhalos
• The infall of dwarf satellite galaxies are influenced by their host's massive accretions
• Variation of the subhalo abundance in dark matter halos
• The Effects of Halo-to-Halo Variation on Substructure Lensing
• Dark matter halo occupation: environment and clustering
• Observational Constraints on the Modified Gravity Model (MOG) Proposed by Moffat: Using the Magellanic System
• Subhalo abundance and satellite spatial distribution in Milky Way-Andromeda-like paired haloes