dark matter halos

Dark Matter Halos

A.Klypin

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Major codes:

GADET Springel, SDM White

PKDGRAV - GASOLINE

Quinn, Steidel, Wadsley, Governato, Moore

ART Kravtsov, Klypin, N.Gnedin, Gottlober

ENZO Bryan, Norman

•N-body•Hydro•Cooling/Heating/SF•Metal enrichment•Radiative transfer•Multistepping/Multiple masses

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QuickTime™ and aYUV420 codec decompressor

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Non-linear evolution: from Zeldovich approximation to DM halos

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QuickTime™ and aYUV420 codec decompressor

are needed to see this picture.

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Local Group:z=0

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Local Group:z=1

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Local Group:z=7

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Mass function of distinct halos

• It started long ago: 32 years to be precise

• Now we live through 5th generation of this.

Warren etal 2005: 13 sims each with 1G particles

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Halo Mass Function depends on environment

• Sheth&Tormen 2002

• GottlÖber etal 2003

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Clustering: DM halos and L

Conroy, Wechsler, Kravtsov (2005): N-body onlyGet 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

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SDSS

DM galaxies

DM

SDSS: z=0SDSS: z=0

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DEEP: z=1DEEP: z=1

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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

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Cusps: simulationsDiemand etal 2004

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Tasitsiomi etal 2004

Slope gets shallower with decreasing radius, but it does not go below -1

Consistent with what other groups found

Navarro etal 2004

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Profiles are NOT

NFW

Navarro etal 2004Merritt, Navarro 2004Prada etal 2005

ρ(r)=ρo exp(-2nr1/n)+<ρ>

n=6-8 3D Sersic

NFW

NFW

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Average profiles of

Milky Way-size halos

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Infall velocities on halos of

different mass

Prada et al 2005

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RMS velocity of isolated halos

Full: simulationsDash: solution of Jeans equation

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SDSS and LCDM: surface number density

of satellites around isolated

galaxies

LCDM

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Evolution of Halo structure• Most of the

accreted mass stays in the outer region of halo.

Diemand etal 2005

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Evolution of Halo structure

Dwarf Halos at high zcusp evolves very little.

Colin etal 2003

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Halo Concentrations Bullock etal 2003

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VoidsR>10Mpc

Patiri et al 2006: SDSS

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Number-density Profiles of Voids:

n(R)/<n>

SDSS

LCDM

Patiri et al 2006

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