Properties of dark matter haloes as a function of local environment density

Christoph T. Lee, Joel R. Primack, Peter Behroozi, Aldo Rodríguez-Puebla, Doug Hellinger, Avishai Dekel

Research output: Contribution to journalArticlepeer-review

36 Scopus citations

Abstract

We study how properties of discrete dark matter haloes depend on halo environment, characterized by the mass density around the haloes on scales from 0.5 to 16 h−1 Mpc. We find that low-mass haloes (those less massive than the characteristic mass MC of haloes collapsing at a given epoch) in high-density environments have lower accretion rates, lower spins, higher concentrations and rounder shapes than haloes in median density environments. Haloes in median- and low-density environments have similar accretion rates and concentrations, but haloes in low-density environments have lower spins and are more elongated. Haloes of a given mass in high-density regions accrete material earlier than haloes of the same mass in lower density regions. All but the most massive haloes in high-density regions are losing mass (i.e. being stripped) at low redshifts, which causes artificially lowered NFW scale radii and increased concentrations. Tidal effects are also responsible for the decreasing spins of low-mass haloes in high-density regions at low redshifts z < 1, by preferentially removing higher angular momentum material from haloes. Haloes in low-density regions have lower than average spins because they lack nearby haloes whose tidal fields can spin them up. We also show that the simulation density distribution is well fit by an extreme value distribution, and that the density distribution becomes broader with cosmic time.

Original languageEnglish (US)
Pages (from-to)3834-3858
Number of pages25
JournalMonthly Notices of the Royal Astronomical Society
Volume466
Issue number4
DOIs
StatePublished - May 1 2017
Externally publishedYes

Keywords

  • Dark matter
  • Galaxies: haloes
  • Large-scale structure of Universe
  • Methods: numerical

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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