The giant arc statistics in the three year WMAP cosmological model

G. L. Li; S. Mao; Y. P. Jing; H. J. Mo; L. Gao; W. P. Lin

doi:10.1111/j.1745-3933.2006.00230.x

paper

The giant arc statistics in the three year WMAP cosmological model

arXiv:astro-ph/0608192 · doi:10.1111/j.1745-3933.2006.00230.x

Abstract

We use high-resolution $N$ -body simulations to investigate the optical depth of giant arcs with length-to-width ratio larger than 7.5 and 10 in the `standard' $\LCDM$ model with $σ_{8} = 0.9$ and $Ω_{m, 0} = 0.3$ and a model based on three-year Wilkinson Microwave Anisotropy Probe (WMAP) data. We find that, in dark-matter only simulations, the lensing probability in the three-year WMAP model (with $σ_{8} = 0.74$ and $Ω_{m, 0} = 0.238)$ decreases by a factor of $\sim 6$ compared with that in the `standard' $\LCDM$ model. The effects of baryonic cooling, star formation and feedbacks are uncertain, but we argue that baryons will only increase the the lensing cross-section by a moderate factor, $\sim 2$ . We conclude that the low central value of $σ_{8}$ and $Ω_{m, 0}$ preferred by the WMAP three-year data may be too low to be compatible with observations if conventional assumptions of the background source population are correct.

6 pages, 4 figures, 1 table, accepted by MNRAS letters

The giant arc statistics in the three year WMAP cosmological model

Abstract

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