MOA-II Galactic microlensing constraints: the inner Milky Way has a low dark matter fraction and a near maximal disc
MOA-II Galactic microlensing constraints: the inner Milky Way has a low dark matter fraction and a near maximal disc
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MOA-II 银河系微透镜约束：银河系内部暗物质比例较低，盘面接近最大
DOI：
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Matthieu Portail
中科院分区：
文献类型：
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作者：
C. Wegg;O. Gerhard;Matthieu Portail
微透镜提供了一个独特的工具，打破恒星暗物质简并在银河系内部。我们结合联合收割机N体动力学模型拟合银河系的Boxy/花生球与指数盘模型外，并计算微透镜的属性。考虑到与MOA-II修正数据一致的模型范围，我们发现银河系内部的暗物质分数很低：在恒星自转曲线的峰值处，圆速度的一部分f_v=（0.88\pm0.07）$是重子的（在1\sigma $时，f_v > 0.72$在2\sigma $时）。这些结果与EROS-II微透镜调查中对较亮分辨恒星的约束一致，其中我们发现f_v=（0.9\pm0.1）$为1\sigma $。我们的基准模型的磁盘尺度长度为2.6kpc，和一个低暗物质分数为12%的凸起，同意修订后的MOA-II和EROS-II微透镜数据。所需的重子分数，以及由此产生的暗物质的低贡献，是一致的NFW配置文件所产生的无耗散宇宙学模拟在银河系质量星系。它们也与最近的银河系质量晕温和绝热收缩的处方一致，而不需要强反馈，但最近对局部暗物质密度的测量存在一些张力。来自较大OGLE-III样品的微透镜光学深度可以进一步改善这些限制。
Microlensing provides a unique tool to break the stellar to dark matter degeneracy in the inner Milky Way. We combine N-body dynamical models fitted to the Milky Way's Boxy/Peanut bulge with exponential disk models outside this, and compute the microlensing properties. Considering the range of models consistent with the revised MOA-II data, we find low dark matter fractions in the inner Galaxy: at the peak of their stellar rotation curve a fraction $f_v=(0.88\pm0.07)$ of the circular velocity is baryonic (at $1\sigma$, $f_v > 0.72$ at $2\sigma$). These results are in agreement with constraints from the EROS-II microlensing survey of brighter resolved stars, where we find $f_v=(0.9\pm0.1)$ at $1\sigma$. Our fiducial model of a disk with scale length 2.6kpc, and a bulge with a low dark matter fraction of 12%, agrees with both the revised MOA-II and EROS-II microlensing data. The required baryonic fractions, and the resultant low contribution from dark matter, are consistent with the NFW profiles produced by dissipationless cosmological simulations in Milky Way mass galaxies. They are also consistent with recent prescriptions for the mild adiabatic contraction of Milky Way mass haloes without the need for strong feedback, but there is some tension with recent measurements of the local dark matter density. Microlensing optical depths from the larger OGLE-III sample could improve these constraints further when available.
影响因子：
4.8
作者：
J. Binney;T. Piffl
通讯作者：
J. Binney;T. Piffl