Phantom Dark Energy, Cosmic Doomsday, and the Coincidence Problem
Abstract
Phantom dark energy models, with w < -1, are characterized by a future singularity and therefore a finite lifetime for the universe. Because the future singularity is triggered by the onset of dark-energy domination, the universe spends a significant fraction of its total lifetime in a state for which the dark energy and matter densities are roughly comparable. We calculate, as a function of w, the fraction of the total lifetime of the universe for which the dark energy and matter densities differ by less than the ratio r_0 in either direction. For r_0 = 10, this fraction varies from 1/3 to 1/8 as w varies from -1.5 to -1.1; the fraction is smaller for smaller values of r_0. This result indicates that the coincidence problem is significantly ameliorated in phantom-dominated cosmologies with a future singularity.
Keywords
Cite
@article{arxiv.astro-ph/0410508,
title = {Phantom Dark Energy, Cosmic Doomsday, and the Coincidence Problem},
author = {Robert J. Scherrer},
journal= {arXiv preprint arXiv:astro-ph/0410508},
year = {2009}
}
Comments
4 pages, 1 figure, more references and discussion added, to appear in Phys. Rev. D