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Cardassian Expansion: Constraints from Compact Radio Source Angular Size versus Redshift Data

Zong-Hong Zhu·Masa-Katsu Fujimoto
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Abstract

The ``Cardassian Expansion Scenario'' was recently proposed by Freese and Lewis (2002) as an alternative to a cosmological constant in explaining the current accelerating universe. In this paper we investigate observational constraints on this scenario from recent measurements of the angular size of high-$z$ compact radio sources compiled by Gurvits et al. (1999). We show that the allowed intervals for $n$ and $z_{eq}$, the two parameters of the Cardassian model, are heavily dependent on the value of the mean projected linear size $l$. However, the best fit to the current angular size data prefers the conventional flat $Λ$CDM model to this Cardassian expansion proposal, though the latter is cosmologically credible and compatible with the $Θ- z$ diagram for some values of $l$.

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BibTeXRIS

Zong-Hong Zhu, Masa-Katsu Fujimoto. 2002-12-09. Cardassian Expansion: Constraints from Compact Radio Source Angular Size versus Redshift Data. https://doi.org/10.1086/344171

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