Constraints on generalized Chaplygin gas model including gamma-ray bursts  

作　　者：Fa-Yin Wang Zi-Gao Dai Shi Qi 

机构地区：[1]Department of Astronomy, Nanjing University, Nanjing 210093, China [2]Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008, China [3]Joint Center for Particle, Nuclear Physics and Cosmology, Nanjing University- Purple Mountain Observatory, Nanjing 210093, China

出　　处：《Chinese Journal of Astronomy and Astrophysics》2009年第5期547-557,共11页中国天文和天体物理学报（英文版）

基　　金：supported by the National Natural Science Foundation of China(grants 10221001, 10640420144 and 10873009) ;the National Basic Research Program of China(973 program) No. 2007CB815404.;Fa-Yin Wang was also supported by the Jiangsu Project Innovationfor PhD Candidates (CX07B-039z).;Shi Qi was supported by the Scientific Research Foundation ofGraduate School of Nanjing University.

摘　　要：Generalized Chaplygin gas （whose equation of state is PGCG = -A/ρGCG^α） was proposed as a candidate for unification of dark energy and dark matter. We investigate constraints on this model with the latest observed data. We test the model with type-Ia supernovae （SNe Ia）, cosmic microwave background （CMB） anisotropy, X-ray gas mass fractions in clusters, and gamma-ray bursts （GRBs）. We calibrate the GRB luminosity relations without assuming any cosmological models using SNe Ia. We show that GRBs can extend the Hubble diagram to higher redshifts （z 〉 6）. The GRB Hubble diagram is well behaved and delineates the shape of the Hubble diagram well. We measure As≡A/ρGCG,0^α＋1 =0.68-0.08^＋0.04（where PGCG,0 is the energy density today） and α=-0.22 -0.13^＋0.15 at the 1σ confidence level using all the datasets. Our results rule out the standard Chaplygin gas model （α = 1） at the 3σ confidence level. The ACDM is allowed at the 2σ confidence level. We find that acceleration could have started at a redshift of z - 0.70. The concordance of the generalized Chaplygin gas model with the age estimate of an old high redshift quasar is found. In addition, we show that GRBs can break the degeneracy between the generalized Chaplygin gas model and the XCDM model.Generalized Chaplygin gas （whose equation of state is PGCG = -A/ρGCG^α） was proposed as a candidate for unification of dark energy and dark matter. We investigate constraints on this model with the latest observed data. We test the model with type-Ia supernovae （SNe Ia）, cosmic microwave background （CMB） anisotropy, X-ray gas mass fractions in clusters, and gamma-ray bursts （GRBs）. We calibrate the GRB luminosity relations without assuming any cosmological models using SNe Ia. We show that GRBs can extend the Hubble diagram to higher redshifts （z 〉 6）. The GRB Hubble diagram is well behaved and delineates the shape of the Hubble diagram well. We measure As≡A/ρGCG,0^α＋1 =0.68-0.08^＋0.04（where PGCG,0 is the energy density today） and α=-0.22 -0.13^＋0.15 at the 1σ confidence level using all the datasets. Our results rule out the standard Chaplygin gas model （α = 1） at the 3σ confidence level. The ACDM is allowed at the 2σ confidence level. We find that acceleration could have started at a redshift of z - 0.70. The concordance of the generalized Chaplygin gas model with the age estimate of an old high redshift quasar is found. In addition, we show that GRBs can break the degeneracy between the generalized Chaplygin gas model and the XCDM model.

关 键 词：GAMMA-RAYS bursts -- cosmology theory 

分 类 号：P159[天文地球—天文学] V211.3[航空宇航科学与技术—航空宇航推进理论与工程]