Constraints on Dark Energy state equation with varying pivoting redshift
| Autor: | Scovacricchi, Dario, Bonometto, Silvio A., Mezzetti, Marino, La Vacca, Giuseppe |
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| Rok vydání: | 2012 |
| Předmět: | |
| Zdroj: | New Astronomy, 26 (2014) 106--111 |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1016/j.newast.2013.07.005 |
| Popis: | We assume the DE state equations w(a) = w_0+w_a(a_p-a), and study the dependence of the constraints on w_0 and w_a coefficients on the pivoting redshift 1+z_p=1/a_p. Coefficients are fitted to data including WMAP7, SNIa (Union 2.1), BAO's (including WiggleZ and SDSS results) and H_0 constraints. The fitting algorithm is CosmoMC. We find specific differences between the cases when neutrino mass is allowed or disregarded. More in detail: i) The z_p value yielding uncorrelated constraints on w_0 and w_a is different in the two cases, holding ~0.25 and ~0.35, respectively. (ii) If we consider the intervals allowed to w_0, we find that they shift when z_p increases, in opposite directions for vanishing or allowed neutrino mass. This leads to no overlap between 1sigma intervals already at z_p >~0.4. (iii) The known effect that a more negative state parameter is required to allow for neutrino mass displays its effects on w_a, rather than on w_0. (iv) The w_0-w_a constraints found by using any pivot z_p can be translated into constraints holding at a specific z_p value (0 or the z_p where errors are uncorrelated). When we do so, error ellipses exhibit a satisfactory overlap. Comment: 13 pages, 7 figures, 2 tables |
| Databáze: | arXiv |
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