光锥中强引力透镜的数值模拟  

Strong Lensing Simulation in a Light Cone

作　　者：高钢杰[1,2] 

机构地区：[1]中国科学院上海天文台,星系宇宙学重点实验室,上海200030 [2]中国科学院研究生院,北京100039

出　　处：《天文学进展》2010年第3期279-289,共11页Progress In Astronomy

基　　金：国家自然科学基金资助项目(10533030,10821302,10878001);973项目(2007CB815402)

摘　　要：根据高精度宇宙学N体数值模拟输出的星系团以及星系团X射线光度和质量的经验关系:L-M,在红移区间(0.14,0.3)内构建了一个X射线波段流量限为3×10^(-19)J·s^(-1)·cm^(-2)(如Local Cluster Substructure Survey,缩写为LoCuSS )的大质量星系团样本。利用高分辨率的Ray-tracing数值模拟对包含真实观测信息(即红移、大小和形状)的COSMOS背景星系源进行单个透镜的成像模拟,并统计星系团不同投影方向的巨弧(即L/W>10)产生效率。依据数值模拟立方体的尺度建立观测光锥,再根据光锥内不同红移区间所占立方体的体积比例用对应数量、红移的透镜对光锥进行随机填充,通过平均它们的透镜效率,最终计算得到光锥内的平均强引力透镜效率为3.22_(-1.47)^(+2.73)×10^(-2)。Mock clusters from a high-resolution N-body simulation have been used to investigate the mean lensing efficiency in a light cone.The empirical relation between X-ray luminosity and cluster mass,i.e.,L-M,is converted to the adopted ACDM cosmology to obtain the mean X-ray luminosity of the simulated clusters.Given a log-normal conditional probability distribution p（L｜M,z）,the observational X-ray luminosity of the massive cluster can be well mimicked. According to the cluster redshift and the cosmology,the observed X-ray flux can be measured after the so-called K-correction.Chosen a certain flux limit,e.g.,3×10^（-19）J·s^（-1）·cm^（-2） as in Local Cluster Substructure Survey（LoCuSS）,a simulated flux-limited cluster sample which contains 150 clusters in total can be constructed from the simulation outputs in the redshift range of（0.14～0.3）. Clusters in this flux-limited sample are taken as foreground lenses to look at 100 randomly selected tiles of the background Cosmological Evolution Survey（COSMOS） galaxies,whose properties （i.e.,redshift,size and ellipticity） have been well investigated in Gao et al.（2009）.All these real source properties are included in the lensing simulation to pin down the uncertainties.Three representative lines of sight are explored for the strong lensing probability,which are aligned with the directions of the simulation box sides.For each of the three orthogonal projections of the clusters,10 random regions among each source tile are lensed by foreground gravitational field. Since there are 150 clusters in the parent sample,4.5×10~5 mock observations in total are carried out in the lensing simulation.The lensed images of L/W larger than 10 are considered as the giant arcs,which are counted to get the mean lensing efficiency for each projection. Based on the scale of our simulation box,one can construct a 41°light cone,which is divided into regions in three redshift bins following the simulation output redshifts.The number of clusters needed to fill

关 键 词：宇宙学 星系团 引力透镜 

分 类 号：P159[天文地球—天文学]