Determining cosmological parameters with current observational data TPCSF Li Hong 2008.12.10

CMB 、LSS and SN The cosmological observations play Recent years Cosmology became more and more accurate CMB 、LSS and SN Complementary, GRB and WL also make remarkable progress ! The cosmological observations play a crucial role in understanding universe !

outline The global fitting analysis Constraints on EOS including GRBs The constraints on cosmological parameters with the latest observational data Constraints on EOS including GRBs Simulations for LAMOST Summary

Global fitting procedure Parameterization of EOS: Perturbation included G.-B. Zhao, et al., PRD 72 123515 (2005) Method : modified CosmoMC Calculated at ShangHai Supercomputer Center (SSC) Data : CMB+LSS+SNe Cosmological parameters: For simplicity, usually consider flat Universe

Current constraint on the equation of state of dark energy Quintessece Quintom A Quintom B Phantom WMAP5 result E. Komatsu et al., arXiv:0803.0547 Xia, Li, Zhao, Zhang, in preparation Difference: Data: SN (SNLS+ESSENCE+Riess et al.) vs SN (307,Kowalski et al., arXiv:0804.4142) Method: WMAP distance prior vs Full CMB data. However, results similar (Li et al., arXiv: 0805.1118) Status: 1) Cosmological constant fits data well; 2) Dynamical model not ruled out; 3) Best fit value of equation of state: slightly w across -1  Quintom model

Arxiv: 0805.1118, Accepted by APJ Lett.

For the published version :

Take into account the recent weak lensing data

Global analysis of the cosmological parameters including GRBs Results from the global analysis with WMAP3+LSS+SNe(Riess 182 samples)+GRBs (Schaefer 69 sample) New method for solution of the circulation problem

the 69 modulus published by Schaefer (in astro-ph/0612285)

Bias with only GRB Need global analysis

Hong Li, M. su, Z.H. Fan, Z.G. Dai and X.Zhang, astro-ph/0612060, Phys.Lett.B658:95-100,2008 WMAP3+LSS+SN WMAP3+LSS+SN+GRB

The relevant papers on studies with GRBs: E.L.Wright astro-ph/0701584

F.Y. Wang, Z. G. Dai and Z. H. Zhu, astro-ph/0706.0938

Problems: The circulation problem : Due to the lack of the low-redshift GRBs, the experiential correlation is obtained from the high-redshift GRBs with input cosmology !

What is the circulation problem? Due to the lack of the low-redshift GRBs, the experiential correlations are obtained from the high-redshift GRBs with input cosmology which we intend to constrain, it lead to the circulation problem! From the observation, we can get: S_r, t_j, n, eta_r, E_peak S_r is the fluence of the r-ray; t_j is the Break time; n is the circumburst particle Density; eta_r is the fraction of the kinetic Energy that translate to the r-rays; E_peak is the peak energy of the spectrum With a fire ball GRB model: Ghirlanda et al.

Input a cosmology Usually Get A & C

A new method for overcoming the circulation problem for GRBs in global analysis Hong Li et al., APJ 680, 92 (2008) Correlation as an example: We take We let A and C free: We integrate them out in order to get the constraint on the cosmological parameter: We can avoid the circulation problem ! And method can apply to the other correlations.

For flat universe !

With free !

For flat universe !

The constraints on A and C related with the correlation: e., in the literature C is set to [0.89, 1.05]; A is set to 1.5 One can find that, this will lead to the bias to the final constraints on The cosmological parameters!

Simulations for LAMOST www.lamost.org z~ 0.2 n~ galaxies H.Feldman, et al. Astrophys.J. 426, 23 (1994) Firstly we take the bias factor: b=1 Then we let b free, see the following

Simulated power spectrum Fiducial model:

About other simulations Planck: we assume the isotropic noise with variance and a symmetric gaussian beam of 7 arcminutes full-width half-maximum : A. Lewis, Phys.RevD71,083008(2005) (See the paper by arXiv: 0708.1111, J.-Q. Xia, H. Li et al.) SNLS: ~ 500 SN Ia

Constraint on cosmological parameters with LAMOST

Constraints on EoS of Dark Energy

Constraint on absolute neutrino mass

SUMMARY Our results on determining EOS of DE with MCMC from WMAP+SDSS+SN(+GRBS) ; Cosmological constant fits the current data well at 2 sigma; Quintom is mildly favored ; The Future observation like Planck and LAMOST will improve the constraints H. Li, J.-Q. Xia, Zu-Hui Fan and X. Zhang, JCAP 10 (2008) 046

Thank You !