嵌入零厚度圆盘的自洽非球形等温晕
Self-consistent nonspherical isothermal halos embedding zero-thickness disks
摘要：
星系自转曲线的晕-晕分解一般是以参数化的方式进行的。通过假设晕分布函数为麦克斯韦分布，我们构造了嵌入零厚度圆盘的非球形等温晕的自洽模型。这里开发的方法可以用来研究其他基于物理的选择晕分布函数和伴随着一个凸起的磁盘的情况下。在初步的研究中，我们注意到在标度函数R_Ω和h之间存在着微调，分别表征了盘的旋转曲线和光度轮廓的上升，这令人惊讶地适用于高表面亮度和低表面亮度星系。这种经验相关性确定了一个比旋转曲线的平滑度和平坦度所要求的更强的共谋（盘-晕共谋）。对于非常不同的盘与晕质量比，自洽模型的特征是平滑而平坦的旋转曲线，因此表明阴谋并不像人们想象的那么戏剧性。对于一个典型的旋转曲线，在V_{\infty}（其精确值也可以作为一个自由参数处理）处的旋转曲线是渐近平坦的，以及一个典型的盘的密度分布，自洽模型由两个无量纲参数表征，它们对应于标准盘晕分解的维度尺度（盘质光比M/L和晕中心密度）。我们表明，如果旋转曲线被分解，通过我们的自洽模型，磁盘晕简并被删除，典型的旋转曲线拟合低于最大磁盘处方的模型。对NGC 3198的研究也得到了类似的结果。最后，我们量化的扁的球状晕，这是显着的，特别是在可见的磁盘的规模。
英文摘要：
Disk-halo decompositions of galaxy rotation curves are generally performed in a parametric way. We construct self-consistent models of nonspherical isothermal halos embedding a zero-thickness disk, by assuming that the halo distribution function is a Maxwellian. The method developed here can be used to study other physically-based choices for the halo distribution function and the case of a disk accompanied by a bulge. In a preliminary investigation we note the existence of a fine tuning between the scalelengths R_Ω and h, respectively characterizing the rise of the rotation curve and the luminosity profile of the disk, which surprisingly applies to both high surface brightness and low surface brightness galaxies. This empirical correlation identifies a much stronger conspiracy than the one required by the smoothness and flatness of the rotation curve (disk-halo conspiracy). The self-consistent models are characterized by smooth and flat rotation curves for very different disk-to-halo mass ratios, hence suggesting that conspiracy is not as dramatic as often imagined. For a typical rotation curve, with asymptotically flat rotation curve at V_{\infty} (the precise value of which can also be treated as a free parameter), and a typical density profile of the disk, self-consistent models are characterized by two dimensionless parameters, which correspond to the dimensional scales (the disk mass-to-light ratio M/L and the halo central density) of standard disk-halo decompositions. We show that if the rotation curve is decomposed by means of our self-consistent models, the disk-halo degeneracy is removed and typical rotation curves are fitted by models that are below the maximum-disk prescription. Similar results are obtained from a study of NGC 3198. Finally, we quantify the flattening of the spheroidal halo, which is significant, especially on the scale of the visible disk.
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