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The LCDM paradigm: successes and challenges on scales of galaxies
Anatoly Klypin (NMSU)


LCDM

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· · ·

DM profiles, concentrations, ... Clustering of galaxies: P(k) and correlation functions Satellites: abundance, number-density profiles Galaxies and Dark Matter: abundances


Dwarfs. Not all halos may be bright

Normal galaxies. Normal Halos: all are bright

LMC

Milky Way

108

M



5в

109

M



2в

1010

M



1012 M



10 km/s

30 km/s

50 km/s

170 km/s

Scales of galaxies


Lots of statistics can be now predicted with very high accuracy


Halo Mass function
Full: Sheth&Tormen Symbols: N-body Bolshoi, Spherical overdensity

Correction factor for Sheth&Tormen:

Bolshoi: Klypin et al 2010 Tinker 2008: z=0-2.5


Accurate predictions for Velocity function of distinct halos


Abundance of satellites

Aquarius simulation. Springel et al 2008. WMAP-1

Bolshoi and ViaLactea II. Klypin et al 2010. WMAP-7


Halo Concentration

Small mass

Large mass

Klypin et al 2010

Prada et al 2011


Concentrations of Clusters of galaxies
Prada et al 2011 Median Concentrations

Maccio et al 2008

Probing 100kpc scales



Baryonic acoustic oscillations: Power spectrum

Percival etal 2007


Correlation function on large scales: baryonic oscillations


THE CLUSTERING OF MASSIVE GALAXIES AT z 0.5 FROM THE FIRST SEMESTER OF BOSS DATA

M.White et al 2010

15


Redshift- space correlation function. Full = theory

Real space correlation function. Dot-dash = theory

16


10-50 kpc scales:

Matching Galaxies with Dark Matter Halos

Trujillo-Gomez et al 2010


Abundance matching:

correlation function of galaxies

SDSS

LCDM

18


The probability distribution for the abundance of Magellanic Clouds-like satellites around Milky Way-mass hosts in simulations (colored diamonds).

Observations - LCDM: just enough Magellanic Clouds

Observations

LCDM
Vmax > 50 km/s

Busha et al 2010


Dark matter profiles: standard LCDM
Aquarius simulation. Springel et al 2008. WMAP-1

Central slope is very close to -1
For normal galaxies it does not matter: baryons dominate
100pc

Stadel etal 2009


Adiabatic compression
Red line NFW - compare with black squares. Duffy et al 2010

Adiabatic compression is always present. Do not forget to use it.
compare red lines. Gnedin et al 2004

DM profiles - [dash: no baryions] . Tissera et al 2009


Klypin et al 1999
Moore et al 1999 Early explanation for the discrepancy was photoionization. Tidal stripping: luminous satellites were much larger in the past. The small halos were photo evaporated.

Kravtsov, Gnedin, Klypin 2004


Cla

SDSS: new satellites ssic satellites: about
10

SDSS: about 12 new satellites only 20% of the sky
Correcting for sky coverage: 60 Correcting for distance incompleteness: 300 -600
Koposov etal 2009 Tollerud et al 2008

Newly discovered satellites are very small stellar rms velocities 5-10km/s


How to suppress formation of a galaxy · Star-formation/Supernovae. Dekel · Photoionization/heating (Bullock How to kill of a galaxy
Is there a limit on mass of galaxy?
Vcrit =30-40 km/s

& Silk (1985)

etal 2000)



Fraction of UV ionizing photons that leaks from galaxies and ionizes intergalactic medium

The model is constrained to match a wide range of properties of the present day galaxy population as a whole, but at high redshift it requires an escape fraction of UV photons near unity in order completely to reionize the universe by redshift z >8. In the most successful model the local sources photoionize the pre-galactic region completely by z 10.

In addition to the luminosity function of Milky Way satellites, the model matches their observed luminosity-metallicity relation, their radial distribution and the inferred values of the mass within 300 pc

Font et al 2011


Structure of dwarf galaxies


Very small scales: cusps and cores

NFW

Cusps and rotation curves: too much of DM in central parts of galaxies?

McGaugh et al 2002

31


Simon etal 04:

NGC 4605 Vmax =100km/s

-- Usual problems with NFW. -- Disk is important: normal M/LR=1 M/LK= 0.5

1arcmin


1kpc

Example: UGC8508
Distance 2.5 Mpc MB =-12.9

Russian 6m telescope


HI data

GMRT: India


Velocity of rotation: Observed: 25-30 km/s Theory: 40-50 km/s

Theory predicts too large circular velocity




Abundance of galaxies


Number of galaxies with Vcirc: observations vs LCDM
Overabundance of dwarf galaxies with Vcirc =50km/s This is a different and much worse problem as compared with the `satellites' overabundance.

Observations


Conclusions

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Very accurate estimates for numerous statistics · Tests down to 10 kpc: LCDM is doing fine · Not clear what happens on smaller scales