SYSTEMATIC PROBLEMS WITH USING DARK MATTER SIMULATIONS TO MODEL STELLAR HALOS
SYSTEMATIC PROBLEMS WITH USING DARK MATTER SIMULATIONS TO MODEL STELLAR HALOS
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DOI：
10.1088/0004-637x/783/2/95
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发表时间：
2014-01
期刊：
影响因子：
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通讯作者：
J. Bailin;E. Bell;M. Valluri;G. Stinson;V. Debattista;H. Couchman;J. Wadsley
中科院分区：
文献类型：
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作者：
J. Bailin;E. Bell;M. Valluri;G. Stinson;V. Debattista;H. Couchman;J. Wadsley
可用计算能力的限制迫使恒星晕结构模型采用以下一种或两种简化假设：（1）恒星质量可以“绘制”到祖卫星中的暗物质（DM）粒子上； (2) 可以使用不形成发光星系的纯DM模拟。我们使用一组受控的恒星晕模型来估计这些假设引入的系统误差的大小，在该模型中，我们独立地改变是否观察恒星粒子或绘制的DM粒子，以及是否使用形成重子盘星系的模拟或不形成重子盘的匹配纯DM模拟。我们发现，“绘画”简化降低了晕浓度和内部结构，主要是因为绘画的 DM 粒子与星粒子具有不同的运动学，即使两者都深埋在卫星的势阱中。使用纯 DM 模拟的简化进一步降低了浓度，但增加了内部结构，并导致更扁长的恒星晕。这些差异在浓度上可能是 1.5-7 倍（通过半质量半径测量），在内部密度结构上可能是 2-7 倍。鉴于这种程度的系统不确定性，当观测结果与基于仅 DM 模拟的当前一代恒星晕模型之间的差异小于一个数量级时，人们应该警惕过度解释之间的差异。
The limits of available computing power have forced models for the structure of stellar halos to adopt one or both of the following simplifying assumptions: (1) stellar mass can be “painted” onto dark matter (DM) particles in progenitor satellites; (2) pure DM simulations that do not form a luminous galaxy can be used. We estimate the magnitude of the systematic errors introduced by these assumptions using a controlled set of stellar halo models where we independently vary whether we look at star particles or painted DM particles, and whether we use a simulation in which a baryonic disk galaxy forms or a matching pure DM simulation that does not form a baryonic disk. We find that the “painting” simplification reduces the halo concentration and internal structure, predominantly because painted DM particles have different kinematics from star particles even when both are buried deep in the potential well of the satellite. The simplification of using pure DM simulations reduces the concentration further, but increases the internal structure, and results in a more prolate stellar halo. These differences can be a factor of 1.5–7 in concentration (as measured by the half-mass radius) and 2–7 in internal density structure. Given this level of systematic uncertainty, one should be wary of overinterpreting differences between observations and the current generation of stellar halo models based on DM-only simulations when such differences are less than an order of magnitude.