English

Is the present expansion of the universe really accelerating?

Astrophysics 2009-11-07 v3 General Relativity and Quantum Cosmology High Energy Physics - Phenomenology High Energy Physics - Theory

Abstract

The current observations are usually explained by an accelerating expansion of the present universe. However, with the present quality of the supernovae Ia data, the allowed parameter space is wide enough to accommodate the decelerating models as well. This is shown by considering a particular example of the dark energy equation-of-state wϕpϕ/ρϕ=1/3w_\phi\equiv p_\phi/\rho_\phi=-1/3, which is equivalent to modifying the \emph{geometrical curvature} index kk of the standard cosmology by shifting it to (kα)(k-\alpha) where α\alpha is a constant. The resulting decelerating model is consistent with the recent CMB observations made by WMAP, as well as, with the high redshift supernovae Ia data including SN 1997ff at z=1.755z= 1.755. It is also consistent with the newly discovered supernovae SN 2002dc at z=0.475z=0.475 and SN 2002dd at z=0.95z=0.95 which have a general tendency to improve the fit.

Keywords

Cite

@article{arxiv.astro-ph/0302357,
  title  = {Is the present expansion of the universe really accelerating?},
  author = {R. G. Vishwakarma},
  journal= {arXiv preprint arXiv:astro-ph/0302357},
  year   = {2009}
}

Comments

Replaced with the accepted version to appear in MNRAS