标题： 宇宙常数和巨大弧的统计透镜效应 显示英文标题

标题： Cosmological Constant and Statistical Lensing of Giant Arcs

摘要： 使用孤立等温球模型来研究前景星系团的物质分布，我们研究了平坦宇宙中巨弧的统计特性，这些宇宙带有和不带有宇宙常数。 我们发现，在一个$z=1$ 的宇宙中，当$\Omega_0=0.3$和$\lambda_0 \equiv \Lambda/(3H_0^2)=0.7$时，预测的巨弧相对数量比爱因斯坦-德西特宇宙（$\Omega_0=1, \lambda_0=0$）中的数量大$\sim2$倍。 对于一个依赖于光度的背景星系数密度演化模型，该模型考虑了在$z_s\approx0.4$处暗蓝星系的过密分布，爱因斯坦-德西特宇宙学模型预测大约有$5\%$的具有$L_x > 2 \times 10^{44}$erg s$^{-1}$光度的星团应该拥有长宽比大于10的巨大弧。这比遥远X射线选择的EMSS星团引力透镜调查中观测到的比例低了一个因子$\sim4$，表明星团的物质分布显著偏离简单的等温球或者存在显著的宇宙常数。进一步研究使用更现实的星团模型来限制宇宙常数是有益的。 显示英文摘要

摘要： Using a singular isothermal sphere model for the matter distribution of foreground clusters of galaxies, we study the statistics of giant arcs in flat cosmologies with and without a cosmological constant. We find that the relative number of arcs predicted within $z=1$ in a universe with $\Omega_0=0.3$ and $\lambda_0 \equiv \Lambda/(3H_0^2)=0.7$ is a factor of $\sim2$ larger than the one in the Einstein-de Sitter universe ($\Omega_0=1, \lambda_0=0$). For a luminosity-dependent evolution model of the number density of background galaxies that accounts for the over-density of faint blue galaxies at $z_s\approx0.4$, the Einstein- de Sitter cosmological model predicts that about $5\%$ of clusters of galaxies with an X-ray luminosity $L_x > 2 \times 10^{44}$ erg s$^{-1}$ should have giant arcs with length-to-width ratio larger than 10. This is a factor of $\sim4$ lower than the observed fraction in the gravitational lensing survey of distant X-ray selected EMSS clusters of galaxies, indicating that the matter distribution of clusters of galaxies deviates significantly from simple isothermal spheres or/and the presence of a significant cosmological constant. It is profitable to further study the constraint on the cosmological constant from giant arcs using more realistic cluster models.