A Lonely Giant: The Sparse Satellite Population of M94 Challenges Galaxy Formation
A Lonely Giant: The Sparse Satellite Population of M94 Challenges Galaxy Formation
复制标题
孤独的巨人：M94 稀疏的卫星群挑战星系形成
DOI：
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发表时间：
2018
影响因子：
4.9
通讯作者：
D. Nidever
中科院分区：
文献类型：
--
作者：
A. Smercina;E. Bell;P. Price;R. D’Souza;C. Slater;J. Bailin;A. Monachesi;D. Nidever
“巨型”银河系（MW）质量星系的矮卫星是我们探测低质量暗物质晕的主要探测器。MW和M31的卫星星系的数量和速度最初使星系形成理论学家感到困惑，但现在许多模型都很好地再现了这一点。然而，MW和M31的卫星有代表性吗？星系形成模型是否“过拟合”？这些问题激发了对本星系群外卫星星系的深入搜索。我们对M94星系的“经典”卫星（M - -≥4 × 105 M⊙）进行了深入调查，其投影距离为150kpc。我们只发现了两颗卫星，每颗都有M -−~ 106 M⊙，而在其他四个具有可比数据的MW-质量系统（MW, M31， M81和M101）中有6-12颗这样的卫星。使用星系占据暗物质晕的“标准”处方（晕取自完全流体动力学的EAGLE模拟），我们发现这样一个稀疏的卫星群发生在小于0.2%的mw质量系统中——在5个样本（已知系统+ M94）中小于1%的概率。为了更频繁地产生类似m94的系统，我们通过大幅增加恒星质量-晕质量（SMHM）关系的斜率和散射，使卫星星系的形成比目前预测的更加随机。令人惊讶的是，即使在光晕质量高达1011 M⊙的情况下，SMHM关系也必须改变——这明显高于当前流体动力学模型预测的增加散射的质量尺度。因此，这个“孤独的巨人”稀疏的卫星群提倡对mw质量星系周围的卫星如何形成的想法进行重要修改。
The dwarf satellites of “giant” Milky Way (MW)–mass galaxies are our primary probes of low-mass dark matter halos. The number and velocities of the satellite galaxies of the MW and M31 initially puzzled galaxy formation theorists, but are now reproduced well by many models. Yet, are the MW’s and M31's satellites representative? Were galaxy formation models “overfit”? These questions motivate deep searches for satellite galaxies outside the Local Group. We present a deep survey of the “classical” satellites (M⋆ ≥ 4 × 105 M⊙) of the MW-mass galaxy M94 out to a 150 kpc projected distance. We find only two satellites, each with M⋆ ∼ 106 M⊙, compared with 6–12 such satellites in the four other MW-mass systems with comparable data (MW, M31, M81, and M101). Using a “standard” prescription for occupying dark matter halos (halos were taken from the fully hydrodynamical EAGLE simulation) with galaxies, we find that such a sparse satellite population occurs in <0.2% of MW-mass systems—a <1% probability among a sample of five (known systems + M94). In order to produce an M94-like system more frequently we make satellite galaxy formation much more stochastic than is currently predicted by dramatically increasing the slope and scatter of the stellar mass–halo mass (SMHM) relation. Surprisingly, the SMHM relation must be altered even for halos masses up to 1011 M⊙—significantly above the mass scales predicted to have increased scatter from current hydrodynamical models. The sparse satellite population of this “lonely giant” thus advocates for an important modification to ideas of how the satellites around MW-mass galaxies form.
影响因子：
4.8
作者：
S. Garrison-Kimmel;P. Hopkins;A. Wetzel;J. Bullock;M. Boylan-Kolchin;D. Keres̆;C. Faucher-Giguère;K. El-Badry;A. Lamberts;E. Quataert;R. Sanderson
通讯作者：
S. Garrison-Kimmel;P. Hopkins;A. Wetzel;J. Bullock;M. Boylan-Kolchin;D. Keres̆;C. Faucher-Giguère;K. El-Badry;A. Lamberts;E. Quataert;R. Sanderson
幽灵调查 I 哈勃太空望远镜先进相机用于调查数据
DOI：
10.1088/0067-0049/195/2/18
发表时间：
2011
期刊：
The Astrophysical Journal Supplement Series
影响因子：
--
作者：
Radburn-Smith;de Jong;Bailin;Bullock;Courteau;Dalcanton;Ferguson;Goudfrooij;Holfeltz;Holwerda;Purcell;Streich;Vlajić
通讯作者：
Vlajić