A dark matter profile to model diverse feedback-induced core sizes of ΛCDM haloes
A dark matter profile to model diverse feedback-induced core sizes of ΛCDM haloes
复制标题
DOI：
10.1093/mnras/staa2101
复制
发表时间：
2020-09-01
影响因子：
4.8
通讯作者：
Garrison-Kimmel, Shea
中科院分区：
文献类型：
--
作者：
Lazar, Alexandres;Bullock, James S.;Garrison-Kimmel, Shea
我们分析了54个星系晕的冷暗物质密度分布与真实环境中的反馈（火）-2星系形成物理模拟，每个解决0.5%的晕维里半径。这些晕包含的星系质量范围从超暗矮星（类似于10（4.5）M圆点的M星）到最大的螺旋星系（类似或等于10（11）M圆点的M星），并且具有核心和尖点的密度轮廓。我们使用一个新的，分析密度分布，扩展了标准的双参数Einasto形式，允许一个明显的恒定密度核心的解决最里面的半径，我们的结果的特点。有一个额外的核心半径参数，r（c），这三个参数的核心Einasto配置文件能够更准确地描述我们的反馈影响的暗物质晕比其他三个参数的配置文件中提出的文献。为了与观测结果进行比较，我们提供了r（c）和其他轮廓参数的拟合函数，作为M星和M星/M晕的函数。与过去的研究一致，我们发现暗物质核心的形成在特征恒星与晕质量比M星/M晕接近或等于5 × 10（-3），或M星接近10（9）M圆点时最有效，核心的大小大致相当于星系的半光半径，r（c）接近或等于1-5 kpc。此外，在M星/M晕小于5 × 10 ~（-4）或M星小于或接近10 ~（6）M圆点的星系中，我们没有发现核形成半径大于或接近100 pc的证据。对于银河系大小的星系，重子收缩往往使晕显着更集中和密集的恒星半光半径比DMO运行。然而，即使在银河系尺度下，FIRE-2星系的形成仍然会产生类似或等于0.5-2 kpc大小的小暗物质核心。最近的证据表明，在银河系的暗物质晕中有一个类似于2kpc的核心与这一预期一致。
We analyse the cold dark matter density profiles of 54 galaxy haloes simulated with Feedback In Realistic Environments (FIRE)-2 galaxy formation physics, each resolved within 0.5 per cent of the halo virial radius. These haloes contain galaxies with masses that range from ultrafaint dwarfs (M-star similar to 10(4.5) M-circle dot) to the largest spirals (M-star similar or equal to 10(11) M-circle dot) and have density profiles that are both cored and cuspy. We characterize our results using a new, analytic density profile that extends the standard two-parameter Einasto form to allow for a pronounced constant density core in the resolved innermost radius. With one additional core-radius parameter, r(c), this three-parameter core-Einasto profile is able to characterize our feedback-impacted dark matter haloes more accurately than other three-parameter profiles proposed in the literature. To enable comparisons with observations, we provide fitting functions for r(c) and other profile parameters as a function of both M-star and M-star/M-halo. In agreement with past studies, we find that dark matter core formation is most efficient at the characteristic stellar-to-halo mass ratio M-star/M-halo similar or equal to 5 x 10(-3), or M-star similar to 10(9) M-circle dot, with cores that are roughly the size of the galaxy half-light radius, r(c) similar or equal to 1-5 kpc. Furthermore, we find no evidence for core formation at radii greater than or similar to 100 pc in galaxies with M-star/M-halo < 5 x 10(-4) or M-star less than or similar to 10(6) M-circle dot. For Milky Way-size galaxies, baryonic contraction often makes haloes significantly more concentrated and dense at the stellar half-light radius than DMO runs. However, even at the Milky Way scale, FIRE-2 galaxy formation still produces small dark matter cores of similar or equal to 0.5-2 kpc in size. Recent evidence for a similar to 2 kpc core in the Milky Way's dark matter halo is consistent with this expectation.