The dark side of FIRE: Predicting the population of dark matter subhaloes around Milky Way-mass galaxies
The dark side of FIRE: Predicting the population of dark matter subhaloes around Milky Way-mass galaxies
复制标题
DOI：
10.1093/mnras/stad1395
复制
发表时间：
2023-03
影响因子：
4.8
通讯作者：
M. Barry;A. Wetzel;S. Chapman;J. Samuel;R. Sanderson;Arpit Arora
中科院分区：
文献类型：
--
作者：
M. Barry;A. Wetzel;S. Chapman;J. Samuel;R. Sanderson;Arpit Arora
各种各样的观测活动试图通过测量低质量的暗物质亚晕来测试暗物质模型。尽管预计这些亚晕中没有恒星，但可以通过引力透镜效应或它们对恒星流的引力扰动来探测到这些亚晕。为了对ΛCDM内的亚晕群设定可测量的期望，我们从FIRE-2重子模拟中检查了11个银河系（MW）质量的晕，量化了与恒星流相互作用相关的亚晕的数量和轨道通量：质量低至106 M⊙，距离银河系中心小于50 kpc，穿越z = 0−1（回望= 0−8 Gyr）。我们提供拟合我们的结果及其对亚晕质量，距离和回顾时间的依赖，用于（半）分析模型。在z≈0时，一个典型的mw质量晕在50kpc内包含约16个亚晕>07m⊙（约1个亚晕> 108m⊙）。我们将我们的结果与同样模拟的纯暗物质版本进行了比较：因为它们缺乏中心星系的潜力，它们对亚晕数量的预测高估了2 - 10倍，在更小的距离上更是如此。一个给定mw质量星系周围的亚晕计数随着时间的推移而下降，在z = 1时比在z≈0时高约10倍。在z≈0处，亚晕的轨道速度分布几乎各向同性。在我们的模拟中，我们还发现了4个大麦哲伦云卫星通道的类似物；这些类似物将亚晕数量增加了1.4 - 2.1倍，显著增加了今天MW周围预期的亚晕数量。我们的结果表明，像GD-1这样的流的相互作用速率为每Gyr ~ 5，足以使亚晕流相互作用成为测量暗亚晕的有前途的方法。
A variety of observational campaigns seek to test dark-matter models by measuring dark-matter subhaloes at low masses. Despite their predicted lack of stars, these subhaloes may be detectable through gravitational lensing or via their gravitational perturbations on stellar streams. To set measurable expectations for subhalo populations within ΛCDM, we examine 11 Milky Way (MW)-mass haloes from the FIRE-2 baryonic simulations, quantifying the counts and orbital fluxes for subhaloes with properties relevant to stellar stream interactions: masses down to 106 M⊙, distances ≲ 50 kpc of the galactic center, across z = 0 − 1 (tlookback = 0 − 8 Gyr). We provide fits to our results and their dependence on subhalo mass, distance, and lookback time, for use in (semi)analytic models. A typical MW-mass halo contains ≈16 subhaloes >107 M⊙ (≈1 subhalo >108 M⊙) within 50 kpc at z ≈ 0. We compare our results with dark-matter-only versions of the same simulations: because they lack a central galaxy potential, they overpredict subhalo counts by 2 − 10 ×, more so at smaller distances. Subhalo counts around a given MW-mass galaxy declined over time, being ≈10 × higher at z = 1 than at z ≈ 0. Subhaloes have nearly isotropic orbital velocity distributions at z ≈ 0. Across our simulations, we also identified 4 analogs of Large Magellanic Cloud satellite passages; these analogs enhance subhalo counts by 1.4 − 2.1 times, significantly increasing the expected subhalo population around the MW today. Our results imply an interaction rate of ∼5 per Gyr for a stream like GD-1, sufficient to make subhalo-stream interactions a promising method of measuring dark subhaloes.