Evolution of large scale structures

1
Evolution of large scale structures
The importance of studying dark matter halos
1)in CDM models, all dark matter is in halos of
different mass 2) shaping up luminous objects,
such galaxies and clusters 3) dark matter halos
could be directly detected by gravitational
lensing
2
Physical (Internal) Properties of dark matter
halos
3
Contents

• Density profiles
• Shape and triaxial model of density profiles
• Subhalos and their spatial distribution
• Spin and angular momentum distribution

4
Brief introduction to the simulation methods

• Cosmological simulation
• Cosmological multiple-mass particle resimulation

5
Density profile
6
(No Transcript)
7
(No Transcript)
8
(No Transcript)
9
c(M)
10
NFW Recipe for predicting c(M)
Formation time of progenitor fM
Characteristic Density from the formation time
11
Selection and Scatters

• NFW valid only for 30 percent most virialized
  halos
• Lognormal distribution with sigma_c about 0.2 for
  30 subpopulation or 0.5 for all halos at the
  same mass

Jing (2000)
12
Lognormal distribution
Jing (2000) Bullock et al. 2001
13
Fails to explain the z-dependence of c(M,z)
c(M,z)?1/(1z)
Bullock et al. 2001
14
(No Transcript)
15
(No Transcript)
16
(No Transcript)
17
(No Transcript)
18
Conclusion for this part

• A prescription based MAH for predicting c for
  hierarchical models, is more accurate than
  previous empirical models.
• The prescription, based on the tight relation
  found for Ms-rs, works for individual halos based
  on their MAH
• MAH is universal after scaling at the turning
  point, for halos of 1010 to 1015 Msun

19
Debate on the inner slope of NFW
Moore et al (1998) ApJ 499 L5
Jing Suto (2000),ApJ, 529,L69
Beta1.1 for clusters 1.3 for groups 1.5 for
galaxies
20

• JYP Suto, Y. 2000, ApJ, 529, L69

21
summary

• NFW is a good approximation
• c is log-normal distributed
• The c parameter is determined from MAH (Zhao et
  al. 2004)
• It is still in debate that the inner slope may be
  steeper than NFW and may even depend on halo
  mass.

22
(No Transcript)
23
JYP Suto,Y. 2000,ApJ, 529, L69
24
Determine local density for each particle from 32
nearest neighbors Get iso-density surfaces
after excluding subhalos
25
(No Transcript)
26
Feature1 concentric triaxial model works better
than spherical model
27
(No Transcript)
28
Feature2 density along the major axis fit with
NFW
29
(No Transcript)
30
(No Transcript)
31
(No Transcript)
32
We need to fix the shapes of halos in order to
quantify the density distribution in the triaxial
model
Feature3scaling relation and universal
distributions exists for the shape distributions
33
(No Transcript)
34
(No Transcript)
35
(No Transcript)
36
(No Transcript)
37
Feature4 more elongated at the central region
easy to be included
38
Summary

• Used two large samples of HR simulations
• the concentric triaxial model more accurate
• a COMPLETE set of formulae which can predict the
  tri-axial density profile of halos for a CDM
  model
• can adopt a/c (R)
• Many applications lensing, S-Z effect, x-ray
  distribution of clusters, modeling non-linear
  clustering of DM

39
Mass function of subhalos
40
JYP Suto,Y. 2000,ApJ, 529, L69
41
Radial distribution of subhalos much shallower
than DM
42
Comparing with observation of clusters
43
Comparing with our Milky way
44
Angular Momentum distribution and Spin
distribution
45
(No Transcript)
46
(No Transcript)
47
(No Transcript)