Crossing the phantom divide: theoretical implications and observational status

By S. Nesseris, L. Perivolaropoulos. 2006

326 citations recorded by the source corpus.

If the dark energy equation of state parameter w(z) crosses the phantom divide line w = −1 (or equivalently if the expression d(H2(z))/dz−3Ω0mH02(1+z)2 changes sign) at recent redshifts, then there are two possible cosmological implications. Either the dark energy consists of multiple components with at least one non-canonical phantom component or general relativity needs to be extended to a more general theory on cosmological scales. The former possibility requires the existence of a phantom component which has been shown to suffer from serious theoretical problems and instabilities. Therefore, the latter possibility is the simplest realistic theoretical framework in which such a crossing can be realized. After providing a pedagogical description of various dark energy observational probes, we use a set of such probes (including the Gold SnIa (supernovae type Ia) sample, the first-year SNLS (Supernova Legacy Survey) data-set, the three-year WMAP CMB (Wilkinson Microwave Anisotropy Probe cosmic microwave background) shift parameter, the SDSS (Sloan Digital Sky Survey) baryon acoustic oscillations peak (BAO), the x-ray gas mass fraction in clusters and the linear growth rate of perturbations at z = 0.15 as obtained from the 2dF (Two-Degree Field) Galaxy Redshift Survey) to investigate the priors required for cosmological observations to favour crossing of the phantom divide. We find that a low Ω0m prior (0.2<Ω0m<0.25) leads, for most observational probes (except of the SNLS data), to an increased probability (mild trend) for phantom divide crossing. An interesting degeneracy of the integrated Sachs–Wolfe effect in the CMB perturbation spectrum is also pointed out.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/e667c34436eb187c9c4c21606ddf8a3c0630baa1

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Citations in the corpus

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