A profile in FIRE: resolving the radial distributions of satellite galaxies in the Local Group with simulations
A profile in FIRE: resolving the radial distributions of satellite galaxies in the Local Group with simulations
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DOI：
10.1093/mnras/stz3054
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发表时间：
2019-04
影响因子：
4.8
通讯作者：
J. Samuel;A. Wetzel;E. Tollerud;S. Garrison-Kimmel;S. Loebman;K. El-Badry;P. Hopkins;M. Boylan-Kolchin;C. Faucher-Giguère;J. Bullock;S. Benincasa;J. Bailin
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文献类型：
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作者：
J. Samuel;A. Wetzel;E. Tollerud;S. Garrison-Kimmel;S. Loebman;K. El-Badry;P. Hopkins;M. Boylan-Kolchin;C. Faucher-Giguère;J. Bullock;S. Benincasa;J. Bailin
虽然最近的宇宙学模拟缓解了局部群(LG)卫星星系和Λ冷暗物质宇宙学之间的许多紧张关系，但卫星的空间分布仍然是模拟中物理模型和物理与数值干扰的重要考验。利用FIRE-2宇宙学放大重子模拟，研究了具有10^5$M⊙的卫星围绕8个孤立的银河系(MW)质量宿主星系和4个类LG恒星对的径向分布。我们证明了这些模拟用$M_*\gtrsim$10^5$M⊙解决了卫星的生存和物理破坏问题。模拟结果与LG的观测结果大体一致，覆盖了MW和M31周围的径向轮廓。这一协议并不强烈依赖于卫星质量，即使在距离≲100kpc的情况下也是如此。在寄主的300kpC内，寄主与寄主之间的差异对卫星计数的散布起主导作用，而在50kpC内，时间变化对散布起主导作用。在我们的样本中，质量较大的宿主星系在短距离内卫星较少，这可能是因为通过宿主星系的重子盘加强了对卫星的潮汐破坏。此外，我们量化了与暗物质相关的重子模拟中的亚晕的潮汐损耗，并提供了与距离的函数的拟合。我们的模拟轮廓表明，即使在$M_*\gtrsim$10^5$M⊙，LG的观测也是不完整的：我们预测在MW周围发现2-10颗这样的卫星，在M31附近可能发现6-9颗。为了提供宇宙学背景，我们将我们的结果与SAGA调查中MW类似物周围卫星的径向轮廓进行了比较，发现我们的模拟与大多数SAGA系统大体一致。
While many tensions between Local Group (LG) satellite galaxies and Λ cold dark matter cosmology have been alleviated through recent cosmological simulations, the spatial distribution of satellites remains an important test of physical models and physical versus numerical disruption in simulations. Using the FIRE-2 cosmological zoom-in baryonic simulations, we examine the radial distributions of satellites with $M_*\gt 10^5$ M⊙ around eight isolated Milky Way (MW) mass host galaxies and four hosts in LG-like pairs. We demonstrate that these simulations resolve the survival and physical destruction of satellites with $M_*\gtrsim 10^5$ M⊙. The simulations broadly agree with LG observations, spanning the radial profiles around the MW and M31. This agreement does not depend strongly on satellite mass, even at distances ≲100 kpc. Host-to-host variation dominates the scatter in satellite counts within 300 kpc of the hosts, while time variation dominates scatter within 50 kpc. More massive host galaxies within our sample have fewer satellites at small distances, likely because of enhanced tidal destruction of satellites via the baryonic discs of host galaxies. Furthermore, we quantify and provide fits to the tidal depletion of subhaloes in baryonic relative to dark matter-only simulations as a function of distance. Our simulated profiles imply observational incompleteness in the LG even at $M_*\gtrsim 10^5$ M⊙: we predict 2–10 such satellites to be discovered around the MW and possibly 6–9 around M31. To provide cosmological context, we compare our results with the radial profiles of satellites around MW analogues in the SAGA survey, finding that our simulations are broadly consistent with most SAGA systems.