Redshift-distance relations from type Ia supernova observations

Free access article

Issue		A&A Volume 464, Number 2, March III 2007


Page(s)		465 - 470
Section		Cosmology (including clusters of galaxies)
DOI		http://dx.doi.org/10.1051/0004-6361:20065292

A&A 464, 465-470 (2007)
DOI: 10.1051/0004-6361:20065292

New constraints on grey dust models

A. R. Robaina^{1, 2} and J. Cepa^{2, 3}

¹ Facultad de Física, Universidad de La Laguna, 38071 La Laguna, Tenerife, Spain
e-mail: arobaina@iac.es
² Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Spain
³ Departamento de Astrofísica, Facultad de Física, Universidad de La Laguna, 38071 La Laguna, Tenerife, Spain
e-mail: jcn@iac.es

(Received 27 March 2006 / Accepted 3 August 2006)

Abstract
Extinction due to intergalactic grey dust has been proposed as an alternative to accelerated expansion to account for the dimming of SnIa fluxes beyond $z \simeq 0.5$ . The "replenishing" grey dust model, although fitting the observational data, does not seem to be based on physical assumptions. For this reason, in this paper we propose a new grey dust model whose dust distribution follows the comoving SFR density evolution, a reasonably established phenomenon. This new model is compared with the updated photometric data sample from the High Z Supernova Search Team (HZT). Also, using pairs of supernovae at different redshifts, the possibility of any "patchy" distribution proposed to explain the discrepancies between the "high z" dust model and the SnIa observations at very high redshift ( $z \ge 0.9$ ) is ruled out. Finally, the data are compared with different models with and without dark energy and a best fit to a universe with adimensional parameters $\Omega_{\mathrm{m0}} = 0.31$ and $\Omega_{\mathrm{\Lambda 0}} = 0.69$ is obtained, from which an age of the universe of $t_{0} \simeq 14.6 \times 10^{9}$ years is derived. This age is compatible with the age of the globular clusters using an equation of state $\omega = -1$ and it obviates the need to resort to any kind of phantom energy.

Key words: cosmological parameters -- cosmology: theory -- distance scale -- galaxy: abundances

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