Bibcode
DOI
Prada, Francisco; Klypin, Anatoly A.; Simonneau, Eduardo; Betancort-Rijo, J. E.; Patiri, Santiago; Gottlöber, Stefan; Sanchez-Conde, Miguel A.
Bibliographical reference
The Astrophysical Journal, Volume 645, Issue 2, pp. 1001-1011.
Advertised on:
7
2006
Journal
Citations
137
Refereed citations
125
Description
We study the density profiles of collapsed galaxy-size dark matter halos
with masses 1011 to 5×1012 Msolar
focusing mostly on the halo outer regions from the formal virial radius
Rvir up to 5Rvir-7Rvir. We find that
isolated halos in this mass range extend well beyond Rvir
exhibiting all properties of virialized objects up to
2Rvir-3Rvir: relatively smooth density profiles
and no systematic infall velocities. The dark matter halos in this mass
range do not grow as one naively may expect through a steady accretion
of satellites; i.e., on average there is no mass infall. This is
strikingly different from more massive halos, which have large infall
velocities outside the virial radius. We provide an accurate fit for the
density profile of these isolated galaxy-size halos. For a wide range
0.01Rvir-2Rvir of radii the halo density profiles
are fitted with the approximation
ρ=ρsexp[-2n(x1/n-1)+<ρm>,
where x≡r/rs, <ρm> is the mean
matter density of the universe, and the index n is in the range n=6-7.5.
These profiles do not show a sudden change of behavior beyond the virial
radius. For larger radii we combine the statistics of the initial
fluctuations with the spherical collapse model to obtain predictions for
the mean and most probable density profiles for halos of several masses.
The model gives excellent results beyond 2-3 formal virial radii for the
most probable profile and qualitatively correct predictions for the mean
profile.