Constraining the dark energy and smoothness parameter with type Ia supernovae and gamma-ray bursts

Autor(es)

Busti, V. C. ^[1] ; Santos, R. C. ^[2] ; Lima, J. A. S. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Dept Astron, Sao Paulo - Brazil

^[2] Univ Fed Sao Paulo, Dept Ciencias Exatas & Terra, Diadema, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Physical Review D; v. 85, n. 10, p. 103503, 2012.
• Citações Web of Science: 16

Resumo

The existence of inhomogeneities in the observed Universe modifies the distance-redshift relations thereby affecting the results of cosmological tests in comparison to the ones derived assuming spatially uniform models. By modeling the inhomogeneities through a Zeldovich-Kantowski-Dyer-Roeder approach which is phenomenologically characterized by a smoothness parameter alpha, we rediscuss the constraints on the cosmic parameters based on type Ia supernovae (SNe Ia) and gamma-ray bursts (GRBs) data. The present analysis is restricted to a flat Lambda CDM model with the reasonable assumption that Lambda does not clump. A chi(2) analysis using 557 SNe Ia data from the Union2 compilation data (R. Amanullah et al., Astrophys. J. 716, 712 (2010).) constrains the pair of parameters (Omega(m), alpha) to Omega(m) = 0.27(-0.03)(+0.08) (2 sigma) and alpha >= 0.25. A similar analysis based only on 59 Hymnium GRBs (H. Wei, J. Cosmol. Astropart. Phys. 08 (2010) 020.) constrains the matter density parameter to be Omega(m) = 0.35(-0.24)(+0.62) (2 sigma) while all values for the smoothness parameter are allowed. By performing a joint analysis, it is found that Omega(m) = 0.27(-0.06)(+0.06) and alpha >= 0.52. As a general result, although considering that current GRB data alone cannot constrain the smoothness alpha parameter, our analysis provides an interesting cosmological probe for dark energy even in the presence of inhomogeneities. (AU)

• Processo FAPESP: 04/13668-0 - Cosmologia na era da precisão: energia escura, matéria escura e radiação cósmica de fundo
• Beneficiário: Jose Ademir Sales de Lima
• Modalidade de apoio: Auxílio à Pesquisa - Temático