期刊
ASTRONOMY & ASTROPHYSICS
卷 582, 期 -, 页码 -出版社
EDP SCIENCES S A
DOI: 10.1051/0004-6361/201526461
关键词
cosmological parameters; gamma-ray burst: general; dark energy
资金
- International Cooperation Program CAPES-ICRANet - CAPES - Brazilian Federal Agency for Support and Evaluation of Graduate Education within the Ministry of Education of Brazil
Context. Data from cosmic microwave background radiation (CMB), baryon acoustic oscillations (BAO), and supernovae Ia (SNe-Ia) support a constant dark energy equation of state with w(0) similar to -1. Measuring the evolution of w along the redshift is one of the most demanding challenges for observational cosmology. Aims. We discuss the existence of a close relation for gamma-ray bursts (GRBs), named Combo-relation, based on characteristic parameters of GRB phenomenology such as the prompt intrinsic peak energy E-p,E-i, the X-ray afterglow initial luminosity L-0 and the rest-frame duration tau of the shallow phase, and the index of the late power-law decay alpha(X). We use it to measure Omega(m) and the evolution of the dark energy equation of state. We also propose a new calibration method for the same relation, which reduces the dependence on SNe Ia systematics. Methods. We have selected a sample of GRBs with 1) a measured redshift z; 2) a determined intrinsic prompt peak energy E-p,E-i; and 3) a good coverage of the observed (0.3-10) keV afterglow light curves. The fitting technique of the rest-frame (0 : 3-10) keV luminosity light curves represents the core of the Combo-relation. We separate the early steep decay, considered a part of the prompt emission, from the X-ray afterglow additional component. Data with the largest positive residual, identified as flares, are automatically eliminated until the p-value of the fit becomes greater than 0.3. Results. We strongly minimize the dependency of the Combo-GRB calibration on SNe Ia. We also measure a small extra-Poissonian scatter of the Combo-relation, which allows us to infer from GRBs alone Omega(M) = 0.29(-0.15)(+0.23) (1 sigma) for the Lambda CDM cosmological model, and Omega(M) = 0.40(-0.16) (+0.220) ,w(0) = -1.43(-0.66)(+0.78) for the flat-Universe variable equation of state case. Conclusions. In view of the increasing size of the GRB database, thanks to future missions, the Combo-relation is a promising tool for measuring Omega(m) with an accuracy comparable to that exhibited by SNe Ia, and to investigate the dark energy contribution and evolution up to z similar to 10.
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