Cardassian Expansion: Constraints from Compact Radio Source Angular Size versus Redshift Data
نویسندگان
چکیده
منابع مشابه
Cardassian Expansion: Constraints from Compact Radio Source Angular Size versus Redshift Data
The “Cardassian Expansion Scenario” was recently proposed by Freese & Lewis 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 and coworkers. We show that the allowed intervals for n an...
متن کاملCosmological Constraints from Compact Radio Source Angular Size versus Redshift Data
We use the Gurvits, Kellermann, & Frey compact radio source angular size versus redshift data to place constraints on cosmological model parameters in models with and without a constant or time-variable cosmological constant. The resulting constraints are consistent with but weaker than those determined using current supernova apparent magnitude versus redshift data. Subject headings: cosmology...
متن کاملTight cosmological constraints from the angular-size/redshift relation for ultra-compact radio sources
Some years ago (Jackson and Dodgson 1997) analysis of the angular-size/redshift relationship for ultra-compact radio sources indicted that for spatially flat universes the best choice of cosmological parameters was Ωm = 0.2 and ΩΛ = 0.8. Here I present an astrophysical model of these sources, based upon the idea that for those with redshift z > 0.5 each measured angular size corresponds to a si...
متن کاملConstraints on Cardassian Scenario from the Expansion Turnaround Redshift and the Sunyaev-Zeldovich/X-ray Data
Cosmic acceleration is one of the most remarkable cosmological findings of recent years. Although a dark energy component has usually been invoked as the mechanism for the acceleration, A modification of Friedmann equation from various higher dimensional models provides a feasible alternative. Cardassian expansion is one of these scenarios, in which the universe is flat, matter (and radiation) ...
متن کاملConstraints on Cardassian Expansion
High redshift supernovae and Cosmic Microwave Background data are used to constrain the Cardassian expansion model (Freese & Lewis, 2002), a cosmology in which a modification to the Friedmann equation gives rise to a flat, matter-dominated Universe which is undergoing a phase of accelerated expansion. In particular, the precision of the positions of the Doppler peaks in the CMB angular power sp...
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ژورنال
عنوان ژورنال: The Astrophysical Journal
سال: 2002
ISSN: 0004-637X,1538-4357
DOI: 10.1086/344171