Late universe dynamics with scale-independent linear couplings in the dark sector

Journal Article · Mon Sep 15 04:00:00 EDT 2008 · Physical Review. D, Particles Fields

DOI:https://doi.org/10.1103/PHYSREVD.78.063527· OSTI ID:21250835

Quercellini, Claudia ^[1]; Bruni, Marco; Pietrobon, Davide ^[1]; Balbi, Amedeo ^[1]

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1. Dipartimento di Fisica, Universita di Roma 'Tor Vergata', via della Ricerca Scientifica 1, 00133 Roma (Italy)

We explore the dynamics of cosmological models with two coupled dark components with energy densities {rho}{sub A} and {rho}{sub B} and constant equation of state (EOS) parameters w{sub A} and w{sub B}. We assume that the coupling is of the form Q=Hq({rho}{sub A},{rho}{sub B}), so that the dynamics of the two components turns out to be scale independent, i.e. does not depend explicitly on the Hubble scalar H. With this assumption, we focus on the general linear coupling q=q{sub o}+q{sub A}{rho}{sub A}+q{sub B}{rho}{sub B}, which may be seen as arising from any q({rho}{sub A},{rho}{sub B}) at late time and leads in general to an effective cosmological constant. In the second part of the paper we consider observational constraints on the form of the coupling from SN Ia data, assuming that one of the components is cold dark matter (CDM), i.e. w{sub B}=0, while for the other the EOS parameter can either have a standard (w{sub A}>-1) or phantom (w{sub A}<-1) value. We find that the constant part of the coupling function is unconstrained by SN Ia data and, among typical linear coupling functions, the one proportional to the dark energy density {rho}{sub A} is preferred in the strong coupling regime, |q{sub A}|>1. Models with phantom w{sub A} favor a positive coupling function, increasing {rho}{sub A}. In models with standard w{sub A}, not only a negative coupling function is allowed, transferring energy to CDM, but the uncoupled subcase falls at the border of the likelihood.

• OSTI ID: 21250835
• Journal Information: Physical Review. D, Particles Fields, Journal Name: Physical Review. D, Particles Fields Journal Issue: 6 Vol. 78; ISSN PRVDAQ; ISSN 0556-2821
• Country of Publication: United States
• Language: English

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
COSMOLOGICAL CONSTANT
COSMOLOGICAL MODELS
DENSITY
ENERGY DENSITY
ENERGY TRANSFER
EQUATIONS OF STATE
NONLUMINOUS MATTER
PHANTOMS
STRONG-COUPLING MODEL
UNIVERSE