Radial Distributions of Dwarf Satellite Systems in the Local Volume
Radial Distributions of Dwarf Satellite Systems in the Local Volume
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DOI：
10.3847/1538-4357/abb60b
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发表时间：
2020-06
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影响因子：
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通讯作者：
S. Carlsten;J. Greene;A. Peter;J. Greco;R. Beaton
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作者：
S. Carlsten;J. Greene;A. Peter;J. Greco;R. Beaton
低质量卫星绕银河系（MW）宿主的径向空间分布是模拟小尺度结构的重要基准。该分布对中心盘对亚晕的干扰很敏感，可以表明在MW模拟中观察到的干扰是人为的（即数值的）还是物理的。我们考虑了本地体积（D < 12 Mpc）中12个经过充分调查的类似mw主机的卫星系统的样本，这些卫星系统完全到MV < - 9并且在150投影kpc内。我们研究了卫星的径向分布，并与ΛCDM宇宙学模拟进行了比较，包括大盒宇宙学模拟和mw级晕的高分辨率放大模拟。我们发现观测到的卫星明显比模拟系统更集中。几个观测到的宿主，包括MW，相对于模拟宿主过于集中是~ 2σ的异常值，而没有一个观测到的宿主比模拟宿主更集中。该结果对不同的径向浓度测量方法具有较强的鲁棒性。我们发现这种差异在明亮的MV < - 12卫星上更为显著，这表明这不是观测不完整的结果。我们认为，这种差异可能是由于模拟中的人为干扰，但是，如果是这样，这对于通过观测到的卫星丰度在低质量状态下允许的恒星质量和光晕质量之间的关系具有重要的影响。
The radial spatial distribution of low-mass satellites around a Milky Way (MW)-like host is an important benchmark for simulations of small-scale structure. The distribution is sensitive to the disruption of subhalos by the central disk and can indicate whether the disruption observed in simulations of MW analogs is artificial (i.e., numerical) or physical in origin. We consider a sample of 12 well-surveyed satellite systems of MW-like hosts in the Local Volume (D < 12 Mpc) that are complete to MV < −9 and within 150 projected kpc. We investigate the radial distribution of satellites and compare with ΛCDM cosmological simulations, including big-box cosmological simulations and high-resolution zoom-in simulations of MW-sized halos. We find that the observed satellites are significantly more centrally concentrated than the simulated systems. Several of the observed hosts, including the MW, are ∼2σ outliers relative to the simulated hosts in being too concentrated, while none of the observed hosts are less centrally concentrated than the simulations. This result is robust to different ways of measuring the radial concentration. We find that this discrepancy is more significant for bright, MV < −12 satellites, suggestive that this is not the result of observational incompleteness. We argue that the discrepancy is possibly due to artificial disruption in the simulations, but, if so, this has important ramifications for what relation between stellar mass and halo mass is allowed in the low-mass regime by the observed abundance of satellites.