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Determining cosmological parameters with current observational data

Determining cosmological parameters with current observational data. TPCSF Li Hong 2008.12.10. Recent years Cosmology became more and more accurate. CMB 、 LSS and SN. Complementary, GRB and WL also make remarkable progress !.

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Determining cosmological parameters with current observational data

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  1. Determining cosmological parameters with current observational data TPCSF Li Hong 2008.12.10

  2. 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 !

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

  4. 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

  5. Quintom A Quintessece Phantom Quintom B Current constraint on the equation of state of dark energy 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

  6. Arxiv: 0805.1118, Accepted by APJ Lett.

  7. For the published version :

  8. Take into account the recent weak lensing data

  9. 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

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

  11. Bias with only GRB Need global analysis

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

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

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

  15. 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 !

  16. From the observation, we can get: S_r, t_j, n, eta_r, E_peak With a fire ball GRB model: 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! 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 Ghirlanda et al.

  17. Input a cosmology Get A & C Usually

  18. We take Correlation as an example: A new method for overcoming the circulation problem for GRBs in global analysis Hong Li et al., APJ 680, 92 (2008) 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.

  19. For flat universe !

  20. With free !

  21. For flat universe !

  22. 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!

  23. 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

  24. Fiducial model: Simulated power spectrum

  25. 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

  26. Constraint on cosmological parameters with LAMOST

  27. Constraints on EoS of Dark Energy

  28. Constraint on absolute neutrino mass

  29. 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

  30. Thank You !

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