The distribution function of the Galaxy's dark halo
The distribution function of the Galaxy's dark halo
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DOI：
10.1093/mnras/stv2225
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发表时间：
2015-09
影响因子：
4.8
通讯作者：
J. Binney;T. Piffl
中科院分区：
文献类型：
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作者：
J. Binney;T. Piffl
从银河系暗晕对重子下落的响应是自洽的假设出发，我们建立了一个满足大量观测结果的银河系自洽动力学模型，包括气体终端速度和脉泽的测量，RAVE巡天的18万颗巨星的运动学，以及SDSS的星星计数数据。恒星盘和暗晕都由作用量积分的分布函数（DF）来描述。该模型是通过将Piffl Penoyre & Binney（2015）的工作从单个模型的构建扩展到模型空间的系统搜索而获得的。Piffl等人的模型违反了对终端速度曲线的约束，而我们的模型则尊重这些约束，对薄圆盘和厚圆盘采用了长尺度长度Rd = 3.66kpc。然而，该模型与测量到的核球星微透镜的光学深度不一致，因为它将R <~ 3 kpc的密度的很大一部分归因于暗物质而不是恒星。此外，现在看来，厚盘的尺度长度可能比模型所暗示的要短得多。缩短此缩放长度将导致重新违反来自旋转曲线的约束。我们的结论是，我们现在可以排除银河系暗晕的绝热压缩。
Starting from the hypothesis that the Galaxy's dark halo responded adiabatically to the infall of baryons, we have constructed a self-consistent dynamical model of the Galaxy that satisfies a large number of observations, including measurements of gas terminal velocities and masers, the kinematics of a 180,000 giant stars from the RAVE survey, and star count data from the SDSS. The stellar disc and the dark halo are both specified by distribution functions (DFs) of the action integrals. The model is obtained by extending the work of Piffl Penoyre & Binney (2015} from the construction of a single model to a systematic search of model space. Whereas the model of Piffl et al violated constraints on the terminal-velocity curve, our model respects these constraints by adopting a long scale length R_d=3.66 kpc for the thin and thick discs. The model is, however, inconsistent with the measured optical depth for microlensing of bulge stars because it attributes too large a fraction of the density at R <~ 3 kpc to dark matter rather than stars. Moreover, it now seems likely that the thick disc's scale-length is significantly shorter than the model implies. Shortening this scale-length would cause the constraints from the rotation curve to be violated anew. We conclude that we can now rule out adiabatic compression of our Galaxy's dark halo.