Can dark energy be decaying?

Alam, Ujjaini ; Sahni, Varun ; Starobinsky, Alexei A. (2003) Can dark energy be decaying? Journal of Cosmology and Astroparticle Physics, 2003 . 002_1-002_13. ISSN 1475-7516

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Official URL: http://iopscience.iop.org/1475-7516/2003/04/002

Related URL: http://dx.doi.org/10.1088/1475-7516/2003/04/002

Abstract

We explore the fate of the Universe given the possibility that the density associated with 'dark energy' may decay slowly with time. Decaying dark energy is modelled by a homogeneous scalar field which couples minimally to gravity and whose potential has at least one local quadratic maximum. Dark energy decays as the scalar field rolls down its potential, consequently the current acceleration epoch is a transient. We examine two models of decaying dark energy. In the first, the dark energy potential is modelled by an analytical form which is generic close to the potential maximum. The second potential is the cosine, which can become negative as the field evolves, ensuring that a spatially flat Universe collapses in the future. We examine the feasibility of both models using observations of high redshift type Ia supernovae. A maximum likelihood analysis is used to find allowed regions in the {m, Φ0} plane (m is the tachyon mass modulus and Φ0 the initial scalar field value; m ∼ H0 and Φ0 ∼ MP by order of magnitude). For the first model, the time for the potential to drop to half its maximum value is larger than ∼8 Gyr. In the case of the cosine potential, the time left until the Universe collapses is always greater than ∼18 Gyr (both estimates are presented for Ω0m=0.3, m/H0 ∼ 1, H0 ⋍ 70 km s−1 Mpc−1, and at the 95.4% confidence level).

Item Type:Article
Source:Copyright of this article belongs to Institute of Physics.
Keywords:Supernova Type Ia; Dark Energy Theory
ID Code:46272
Deposited On:04 Jul 2011 11:13
Last Modified:04 Jul 2011 11:13

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