Download presentation
Presentation is loading. Please wait.
Published byProsper Montgomery Modified over 9 years ago
1
Evolution of galaxies and dark matter halos Yipeng Jing Shanghai Astronomical Observatory Main Collaborators: Chunyan Jiang ( 姜春艳), Cheng Li (李成), Donghai Zhao (赵东海), Lan Wang (王岚) …….
2
Taken from S. Faber Theoretical framework for understanding evolution of galaxies and dark matter halos
3
Taken-away conclusions The mass accretion history and the structure evolution of halos established by Zhao et al. (2009) is universally valid not only for LCDM, but also for WDM, HDM (Zhao et al. 2012); A reliable stellar mass-halo mass is directly measured from SDSS, putting useful constraints both on galaxy formation and on cosmology (Li, Cheng et al. 2012); The merger time scale of galaxies is about two times longer than previously thought ( Jiang et al. 2008); Merger leading to a increase of 50-100% in stellar mass of massive galaxies (Wang & YPJ 2010) from z=1 to z=0, consistent with our recent analysis of CFHT data (YPJ 2012)
4
The universal mass accretion history of dark matter haloes
5
N-body cosmological simulations Assumption: MAHs are well simulated with pure dark matter (incomplete, 1024**3) modelnini Γσ8σ8 Ω0Ω0 Λ0Λ0 NpNp LN NQ ηzizi SF11K cut110512 3 1605120.0161481.3 SF20110512 3 1605120.016363.2 SF3110512 3 1605120.01675.0 SF4-2110512 3 1605120.01611.3 LCDM110.20.90.30.7256 3 255120.002572 LCDM210.20.90.30.7512 3 1005120.0172 LCDM310.20.90.30.7512 3 3005120.0336 OCDM110.21.00.30256 3 502560.0272 SCDM110.50.5510256 3 255120.002572 SCDM210.50.5510512 3 1002560.0272
7
Choosing proper variables for modeling Given cosmology and power spectrum, after extrapolated linearly to z=0, linear mass variance of given volume σ is determined by M, and linear critical collapse overdensity δ c by z.
8
Growth rate as a function of scaled “mass” D.H. Zhao et al. (2010)
9
Universal differential relation w-p determines growth rate of halo of mass M D.H. Zhao, et al. ApJ (2009)
10
LCDM Much more accurate than van den Bocsh (2002) or Wecshler et al. (2002)
11
–SCDM & OCDM
12
Another universal correlation t : universe age of final halo t 0.03 : universe age when main progenitor mass is 4% of final halo mass Important Finding!
13
Evolution of halo density profile Combined with MAHs model we presented in part I, c-t correlation can be used to predict the evolution of halo density profile –LCDM1-3
14
Evolution of halo density profile –SCDM1-3
15
Prada et al. (2012) does not work!
16
Zhao et al. (2009) for HDM, without any tuning the parameters, universal indeed
17
Zhao et al. (2009) for Warm DM, without any tuning the parameters, universal indeed (Zhao et al. 2012)
18
Taken from S. Faber Relation between the stellar mass of the central galaxy and host dark matter halo
19
Group catalog of SDSS DR7 (Yang et al. 2008) Sky coverage: 4514 deg^2 Galaxies with redshifts: 369447 (408119) Groups selected: 301237 (300049)
20
Measure the redshift cross correlation function for groups with a given central stellar mass (Li et al. 2012
21
Velocity dispersion – stellar mass relation
22
Halo mass-stellar mass relation
23
Luminosity – halo mass relation
24
Velocity dispersion – stellar mass relation
25
Constraint on cosmology Sigma_8 =0.88 \pm 0.04 Consiste nt with WMAP7 <2sigma
26
Taken from S. Faber Galaxy merger timescale
29
Using ln(m_h/m_sub) for Coulomb logarithm (c.f. Navarro et al. (1994) Predicted friction timescale Measured merger timescale repeated Navarro et al. 1994 But our conclusion is different from theirs
30
Fitting formula Merger timescale for all mergers
31
arXiv:1204.6319
32
Summary The Chandrasekhar formula, as is usually used, under(over)-estimates merger time for minor(major) mergers ; If the Coulomb logarithm is replaced ln(1+lambda), the mass dependence is accounted for correctly; but underestimate The dependence on the circularity is much weaker than the 0.78 power; We have presented a fitting formula and circularity distribution which are sufficient for modeling the merger rate; the scatters are 40%
33
Evolution of the stellar mass and halo mass relation with Halo Occupation Model Halo (and subhalo) catalog from an high resolution N- body simulation Galaxies in halos (central) and subhalos (satellites) are determined by the host halos at infall (Lan Wang et al. 2006), Using the mass functions and correlation functions from SDSS and VVDS (z=0.8) Linear interpolation Unified model Jing & Suto (2000)
34
HOD method: assuming N galaxies in halo of mass M ; First applied to Las Campanas Redshift survey , getting alpha = 0.09 Jing, Mo, Boerner 1998, ApJ, 494, 1
35
Fitting to SDSS (Wang & YPJ 2010)
36
Fitting to VVDS
37
The stellar mass –halo mass relation
38
Stellar mass functions at high redshift
39
How many mergers
40
CFHT and COSMOS (preliminary)
41
Remarks Well understood for the evolution of dark matter halos Still very poorly for evolution of galaxies Combining deep catalogs of galaxies with the dark matter model can yield important clues to the evolution of galaxies
Similar presentations
© 2024 SlidePlayer.com. Inc.
All rights reserved.