| Full text | |
| Author(s): |
Santos‚ RC
;
Cunha‚ JV
;
Lima‚ JAS
Total Authors: 3
|
| Document type: | Journal article |
| Source: | Physical Review D; v. 77, n. 2, p. 023519, 2008. |
| Abstract | |
The presence of inhomogeneities modifies the cosmic distances through the gravitational lensing effect, and, indirectly, must affect the main cosmological tests. Assuming that the dark energy is a smooth component, the simplest way to account for the influence of clustering is to suppose that the average evolution of the expanding Universe is governed by the total matter-energy density whereas the focusing of light is only affected by a fraction of the total matter density quantified by the alpha Dyer-Roeder parameter. By using two different samples of SNe type Ia data, the Omega(m) and alpha parameters are constrained by applying the Zeldovich-Kantowski-Dyer-Roeder luminosity distance-redshift relation for a flat (Lambda CDM) model. Lambda chi(2)-analysis using the 115 SNe Ia data of the Astier et al. sample (2006) constrains the density parameter to be Omega(m)=0.26(-0.07)(+0.17) (2 sigma) while the alpha parameter is weakly limited (all the values is an element of[0,1] are allowed even at 1 sigma). However, a similar analysis based the 182 SNe Ia data of Riess et al. (2007) constrains the pair of parameters to be Omega(m)=0.33(-0.07)(+0.09) and alpha >= 0.42 (2 sigma). Basically, this occurs because the Riess et al. sample extends to appreciably higher redshifts. As a general result, even considering the existence of inhomogeneities as described by the smoothness alpha parameter, the Einstein-de Sitter model is ruled out by the two samples with a high degree of statistical confidence (11.5 sigma and 9.9 sigma, respectively). The inhomogeneous Hubble-Sandage diagram discussed here highlights the necessity of the dark energy, and a transition deceleration/accelerating phase at z similar to 0.5 is also required. (AU) | |
| FAPESP's process: | 04/13668-0 - Cosmology in the era of precision: dark energy, dark matter and background cosmic radiation |
| Grantee: | Jose Ademir Sales de Lima |
| Support Opportunities: | Research Projects - Thematic Grants |