Dark Matter Halos

A.Klypin Dark Matter Halos

GADET Springel, SDM White PKDGRAV - GASOLINE Quinn, Steidel, Wadsley, Governato, Moore ART Kravtsov, Klypin, N.Gnedin, Gottlober ENZO Bryan, Norman Major codes: • N-body • Hydro • Cooling/Heating/SF • Metal enrichment • Radiative transfer • Multistepping/Multiple masses

Non-linear evolution: from Zeldovich approximation to DM halos

Local Group:z=0 7

Mass function of distinct halos Warren etal 2005: 13 sims each with 1G particles • It started long ago: 32 years to be precise • Now we live through 5th generation of this.

Halo Mass Function depends on environment • Sheth&Tormen 2002 • GottlÖber etal 2003

Clustering: DM halos and L • Conroy, Wechsler, Kravtsov (2005): N-body only • Get all halos from high-res simulation • Use maximum circular velocity (NOT mass) • For subhalos use Vmax before they became subhalos • Every halo (or subhalo) is a galaxy • Every halo has luminosity: LF is as in SDSS • No cooling or major mergers and such. Only DM halos • Reproduces most of the observed clustering of galaxies 12

SDSS: z=0 DM galaxies DM SDSS

DEEP: z=1

Dark Matter and Galaxies • - Central DM closely correlates with L: Tully-Fisher, Faber-Jackson • - Morphology-density relation: morphology is mostly defined by halo mass. • - Environment (how many neighbors) is just an indicator of halo mass • Young etal(2003-5), Berrier etal(2005) : Halo occupation distribution→the same conclutions

Cusps: simulations Diemand etal 2004

Tasitsiomi etal 2004 Navarro etal 2004 Slope gets shallower with decreasing radius, but it does not go below -1 Consistent with what other groups found

Profiles are NOT NFW NFW ρ(r)=ρo exp(-2nr1/n)+<ρ> n=6-8 3D Sersic NFW Navarro etal 2004 Merritt, Navarro 2004 Prada etal 2005

Average profiles of Milky Way-size halos

Infall velocities on halos of different massPrada et al 2005

RMS velocity of isolated halos Full: simulations Dash: solution of Jeans equation

SDSS and LCDM: surface number density of satellites around isolated galaxies LCDM

Evolution of Halo structure • Most of the accreted mass stays in the outer region of halo. Diemand etal 2005

Evolution of Halo structure Dwarf Halos at high z cusp evolves very little. Colin etal 2003

Halo Concentrations Bullock etal 2003

VoidsR>10Mpc Patiri et al 2006: SDSS

Number-density Profiles of Voids: n(R)/<n> Patiri et al 2006 SDSS LCDM

DM in central parts of galaxies • Adiabatic compression: old approximation • Adiabatic compression: Gnedin etal 2004

How it works

Structure of our Galaxy Prada etal 2004

Dark Matter Halos