The effects of BCGs on the statistics of large-separation lensed quasars by clusters

作     者：Hong Qi Da-Ming Chen Hong Qi and Da-Ming Chen National Astronomical Observatories,Chinese Academy of Sciences,Beijing 100012,China

作者机构：National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China 

出 版 物：《Research in Astronomy and Astrophysics》 (天文和天体物理学研究（英文版）)

年 卷 期：2011年第11卷第9期

页      面：1003-1018页

核心收录：

学科分类：0709[理学-地质学] 07[理学] 08[工学] 0708[理学-地球物理学] 080401[工学-精密仪器及机械] 070401[理学-天体物理] 0804[工学-仪器科学与技术] 0825[工学-航空宇航科学与技术] 0704[理学-天文学] 0803[工学-光学工程] 

基　　金：supported by the National Natural Science Foundation of China(Grant No. 11073023) the National Basic Research Program of China (973 Program Grant No.2009CB24901) 

主　　题：cosmological parameters    cosmology: theory    galaxies: clusters    gravitational lensing    dark matter 

摘      要：We study the statistics of large-separation multiply-imaged quasars lensed by clusters of galaxies. In particular, we examine how the observed brightest cluster galaxies （BCGs） affect the predicted numbers of wide-separation lenses. We model the lens as an NFW-profiled dark matter halo with a truncated singular isothermal sphere to represent the BCG in its center. We mainly make predictions for the Sloan Digital Sky Survey Quasar Lens Search （SQLS） sample from the Data Release 5 （DRS） in two standard ACDM cosmological models： a model with matter density ΩM = 0.3 and δ8 = 0.9, as is usually adopted in the literature （ACDM1）, and a model suggested by the WMAP seven-year （WMAPT） data with ΩM = 0.266 and δ8 = 0.801. We also study the lensing properties for the WMAP3 cosmology in order to compare with the previous work. We find that BCGs in the centers of clusters significantly enhance the lensing efficiency by a factor of 2 - 3 compared with that of NFW-profiled pure dark matter halos. In addition, the dependence of mass ratios of BCGs to their host halos on the host halo masses reduces the lensing rate by - 20% from assuming a constant ratio as in previous studies, but considering the evolution of this ratio with redshift out to z - 1 would reduce it by - 3%. Moreover, we predict that the numbers of lensed quasars with image separations larger than 10″ in the statistical sample of SQLS from DR5 are 1.22 and 0.47, respectively for ACDM1 and WMAP7 and 0.73 and 0.33 for separations between 10″ and 20″, which are consistent with the only observed cluster lens with such a large separation in the complete SQLS sample.