The Hubble Diagram of Type Ia Supernovae in Non-Uniform Pressure Universes

M. P. Dabrowski; M. A. Hendry

doi:10.1086/305546

paper

The Hubble Diagram of Type Ia Supernovae in Non-Uniform Pressure Universes

arXiv:astro-ph/9704123 · doi:10.1086/305546

Abstract

We use the redshift-magnitude relation, as derived by Dcabrowski (1995), for the two exact non-uniform pressure spherically symmetric Stephani universes with the observer positioned at the center of symmetry, to test the agreement of these models with recent observations of high redshift type Ia supernovae (SNIa), as reported in Perlmutter et al. (1997). By a particular choice of model parameters, we show that these models give an excellent fit to the observed redshifts and (corrected) B band apparent magnitudes of the SNIa data, but for an age of the Universe which is typically about two Gyr greater than in the corresponding Friedmann model. Based on a value of $H_{0} \sim 65$ and assuming $Λ \geq 0$ , the P97 data implies a Friedmann age of at most 13 Gyr and in fact a best-fit (for $q_{0} = 0.5$ ) age of only 10 Gyr. Our Stephani models, on the other hand, can give a good fit to the P97 data with an age of up to 15 Gyr and could, therefore, significantly alleviate the conflict between recent cosmological and astrophysical age predictions. The choice of model parameters is quite robust: one requires only that the non-uniform pressure parameter, $a$ , in one of the models is negative and satisfies $|a| \lte$ 3 km $^{2}$ s $^{- 2}$ Mpc $^{- 1}$ . By allowing slightly larger, negative, values of $a$ one may `fine tune' the model to give an even better fit to the P97 data.

36 pages, 2 tables, 6 figures, AAS Latex 4.0, vastly revised version, new title and abstract, to appear in ApJ

The Hubble Diagram of Type Ia Supernovae in Non-Uniform Pressure Universes

Abstract

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