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Global Analysis of Cosmological Parameters with Current Observations

Recent Cosmology advancements using CMB, LSS, SN, GRB, WL data play a crucial role. Li et al. 2008 study the parameterization of EOS with updated observational data. The global fitting analysis includes simulations for LAMOST. Understanding dark energy constraints is essential for determining the universe's evolution. New methods for solving circulation problems in GRB observations are explored. The study discusses challenges and potential bias factors in current observational data. Future observations with missions like Planck and LAMOST aim to further refine cosmological parameters.

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Global Analysis of Cosmological Parameters with Current Observations

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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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