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arXiv 0904.4098astro-ph.CO
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旋涡星系的结构：恒星质光比的径向分布和暗物质分布

The structure of spiral galaxies: radial profiles in stellar Mass-to-Light ratio and the Dark Matter distribution

Laura Portinari, Paolo Salucci

备注：
12 pages, 10 figures, in press on Astronomy and Astrophysics. Minor text revisions to match published version. Reference added to web-link to http://www.facebook.com/home.php#!/group.php?gid=310260450630
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摘要：

在旋涡星系中观察到的颜色和金属丰度梯度表明，恒星盘的质光比（M*/L）是半径的函数。这确实是由星系盘的化学光度模型预测的。我们研究了螺旋星系中发光物质和暗物质的分布，同时考虑到恒星质量结构研究中通常假定为常数的M*/L -的径向依赖性。从Portinari等人（2004）的化学光度模型出发，结合观测到的星系颜色径向分布，我们得到了旋涡星系星盘的典型平均M*/L分布。我们计算了相应的变质量-光比（VML）恒星表面密度分布，然后VML盘对圆速度的贡献。我们使用后者，结合一个良好的研究暗物质的速度分布，质量模型的共同添加的旋转曲线的Persic等。（1996）。(See http://www.facebook.com/home.php#!/ group.php? gid=310260450630以获取星系运动学的额外信息）通过在VML星盘框架下研究自转曲线，我们在一级近似下证实了在M*/L恒定假设下得到的结果：一个暗物质晕，其核心较浅，内部重子占主导地位，小天体中暗物质的比例较大。然而，暗晕核心和内部重子优势区的尺寸要小一些。VML盘在最内部区域的更强作用对于限制Lambda冷暗物质和MOND场景中的星系质量结构非常重要。

英文摘要：

The colour and metallicity gradients observed in spiral galaxies suggest that the mass-to-light ratio (M*/L) of the stellar disc is a function of radius. This is indeed predicted by chemo-photometric models of galactic discs. We investigate the distribution of luminous and dark matter in spiral galaxies, taking into account the radial dependence of the stellar M*/L - which is usually assumed to be constant in studies of the mass structure. From the chemo-photometric models of Portinari et al. (2004) and in agreement with the observed radial profiles of galaxy colours, we derive the typical average M*/L profile of the stellar discs of spiral galaxies. We compute the corresponding Variable Mass-to-Light (VML) stellar surface density profile and then the VML disc contribution to the circular velocity. We use the latter, combined with a well studied dark matter velocity profile, to mass model the co-added rotation curves of Persic et al. (1996). (See http://www.facebook.com/home.php#!/group.php?gid=310260450630 to retrieve extra information on the kinematics of galaxies) By investigating rotation curves in the framework of VML stellar discs, we confirm, to a first approximation, the scenario obtained with the constant M*/L assumption: a dark matter halo with a shallow core, an inner baryon-dominated region and a larger proportion of Dark Matter in smaller objects. However, the resulting size of the the dark halo core and of the inner baryon dominance region are somewhat smaller. The stronger role that VML discs have in the innermost regions is important to constrain the galaxy mass structure in both Lambda Cold Dark Matter and MOND scenarios.

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