arXiv 0812.07482008-12astro-ph

螺旋引力透镜2237+0305中的恒星和暗物质

Stars and dark matter in the spiral gravitational lens 2237+0305

C. M. Trott, T. Treu, L. V. E. Koopmans, R. L. Webster

备注：: 14 pages, 6 figures, MNRAS, in press
DOI：: 10.1111/j.1365-2966.2009.15780.x

摘要：

本文根据引力透镜约束、HI自转和新的恒星运动学信息，利用10米EISK-Ⅱ望远镜上的ESI摄谱仪获得的数据，构造了一个红移z_l=0.04的螺旋透镜星系2237+0305的质量模型。通过对Mgb-Fe吸收线区域的拟合，得到了该透镜星系在两个垂直方向上的高分辨率旋转曲线和速度色散剖面。恒星自转曲线缓慢上升，在r~1.5”（~1.1 kpc）处出现拐点。速度弥散分布近似平坦。结合光度，运动学和透镜信息被用来构建一个质量模型的四个主要组成部分的系统-暗物质晕，盘，凸起，酒吧。最佳拟合的解有一个暗物质晕，其内部密度对数斜率为rho_DM propto r^-gamma=0.9+/-0.3，一个凸起的M/L_B=6.6+/-0.3 Upperdot_odot，一个圆盘的M/L_B =1.2+/-0.3 Upperdot_odot，与晚型螺旋的测量结果一致。凸起在多个图像所在的内部区域中占主导地位，因此受到观测的严格约束。这个圆盘是次极大的，在2.2r_d处贡献了星系旋转支持的45+/-11%。晕的质量为（2.0+/-0.6）x 10^12 M_odot，恒星与维里的质量比为7.0+/-2.3%，与相同质量的典型星系一致。

英文摘要：

We construct a mass model for the spiral lens galaxy 2237+0305, at redshift z_l=0.04, based on gravitational-lensing constraints, HI rotation, and new stellar-kinematic information, based on data taken with the ESI spectrograph on the 10m Keck-II Telescope. High resolution rotation curves and velocity dispersion profiles along two perpendicular directions, close to the major and minor axes of the lens galaxy, were obtained by fitting the Mgb-Fe absorption line region. The stellar rotation curve rises slowly and flattens at r~1.5" (~1.1 kpc). The velocity dispersion profile is approximately flat. A combination of photometric, kinematic and lensing information is used to construct a mass model for the four major mass components of the system -- the dark matter halo, disc, bulge, and bar. The best-fitting solution has a dark matter halo with a logarithmic inner density slope of gamma=0.9+/-0.3 for rho_DM propto r^-gamma, a bulge with M/L_B=6.6+/-0.3 Upsilon_odot, and a disc with M/L_B =1.2+/-0.3 Upsilon_odot, in agreement with measurements of late-type spirals. The bulge dominates support in the inner regions where the multiple images are located and is therefore tightly constrained by the observations. The disc is sub-maximal and contributes 45+/-11 per cent of the rotational support of the galaxy at 2.2r_d. The halo mass is (2.0+/-0.6) x 10^12 M_odot, and the stellar to virial mass ratio is 7.0+/-2.3 per cent, consistent with typical galaxies of the same mass.

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摘要：

英文摘要：

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