标题： 从引力透镜弧线得到的哈勃空间望远镜星系团的质量分布 显示英文标题

标题： Mass Distributions of HST Galaxy Clusters from Gravitational Arcs

摘要： 尽管宇宙结构形成的N体模拟表明暗物质晕的小半径处密度剖面比等温的更浅，大半径处更陡，但观测到的星系团是否遵循这一剖面仍不确定。 我们使用这种密度剖面之一——不对称NFW剖面来建模由哈勃太空望远镜（HST）观测到的11个带有引力弧的星系团的质量分布。 我们将每个星系团中的星系透镜表征为NFW椭球体，每个椭球体由未知的比例收敛、比例半径、椭圆度和位置角定义。 对于这些参数的一组给定值，我们计算由该透镜系统产生的引力弧。 为了定义与观测到的弧系统拟合的好坏程度，我们定义了一个卡方函数，包括观测弧与重现弧之间的重叠以及预测弧源与源系统观测限制之间的一致性。 我们最小化这个卡方函数以找到最佳再现给定星系团中观测到的弧系统的透镜参数值。 这里我们报告了这11个透镜星系团的最佳拟合透镜参数及其相应的质量估计值。 我们发现基于被定义为NFW椭球体的透镜星系的星系团质量模型能够准确再现观测到的弧，并且此类模型的最佳拟合参数落在模拟定义的合理范围内。 这些结果肯定了NFW剖面作为观测星系团质量分布的有效模型的地位。 显示英文摘要

摘要： Although N-body simulations of cosmic structure formation suggest that dark matter halos have density profiles shallower than isothermal at small radii and steeper at large radii, whether observed galaxy clusters follow this profile is still ambiguous. We use one such density profile, the asymmetric NFW profile, to model the mass distributions of 11 galaxy clusters with gravitational arcs observed by HST. We characterize the galaxy lenses in each cluster as NFW ellipsoids, each defined by an unknown scale convergence, scale radius, ellipticity, and position angle. For a given set of values of these parameters, we compute the arcs that would be produced by such a lens system. To define the goodness of fit to the observed arc system, we define a chi^2 function encompassing the overlap between the observed and reproduced arcs as well as the agreement between the predicted arc sources and the observational constraints on the source system. We minimize this chi^2 to find the values of the lens parameters that best reproduce the observed arc system in a given cluster. Here we report our best-fit lens parameters and corresponding mass estimates for each of the 11 lensing clusters. We find that cluster mass models based on lensing galaxies defined as NFW ellipsoids can accurately reproduce the observed arcs, and that the best-fit parameters to such a model fall within the reasonable ranges defined by simulations. These results assert NFW profiles as an effective model for the mass distributions of observed clusters.