Numerical resolution limits on subhalo abundance matching
Numerical resolution limits on subhalo abundance matching
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DOI：
10.1093/mnras/stt2116
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发表时间：
2013-03
影响因子：
4.8
通讯作者：
Q. Guo;S. White
中科院分区：
文献类型：
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作者：
Q. Guo;S. White
次晕丰度匹配（SHAM）将星系插入暗物质中，只模拟宇宙结构的生长，对星系形成的假设最少。一个星系被放置在每个不同的自约束子晕的潜在最小值处，其光度是子晕早期历史上达到的最大质量（或圆速度）的单调递增函数。星系和暗晕的性质是由匹配模型和观测光度函数联系起来的。然后，模拟的结构可以与观测进行详细的比较，例如，通过星系相关统计，群目录或星系-星系透镜。只有在不受模拟数值限制影响的尺度上，才能从这种比较中得出可靠的天体物理学结论。在这里，我们将Millennium Simulation（MS）的结果与使用SUBFIND定义的subhalo的结果与对更高分辨率的Millennium-II应用相同分析获得的结果进行比较。200千秒差距和2百万秒差距之间的规模的相关统计收敛到20%以内的subhalos与质量在落入对应的至少1000模拟粒子在MS数值收敛的结果，可以得到更低的落入粒子数，如果星系遵循即使在其相关的subhalos已经被潮汐破坏，在最近的半解析星系的femos模拟。这使得强大的模拟和观测之间的比较，在更广泛的动态范围内的质量比假分析，忽略了这样的“孤儿”星系。
Subhalo abundance matching (SHAM) inserts galaxies into dark matter only simulations of the growth of cosmic structure in a way that requires minimal assumptions about galaxy formation. A galaxy is placed at the potential minimum of each distinct self-bound subhalo with a luminosity which is a monotonically increasing function of the maximum mass (or circular velocity) attained over the subhalo’s earlier history. Galaxy and subhalo properties are linked by matching model and observed luminosity functions. Simulated structures can then be compared in detail with observation, for example, through galaxy correlation statistics, group catalogues, or galaxy-galaxy lensing. Robust astrophysical conclusions can be drawn from such a comparison only on scales which are unaffected by the numerical limitations of the simulation. Here we compare results for the Millennium Simulation (MS) with subhalos defined using the SUBFIND to those obtained applying identic al analysis to the much higher resolution Millennium-II. Correlation statistics on scal es between 200 kpc and 2 Mpc converge to within 20% only for subhalos with masses at infall corresponding to at least 1000 simulation particles in the MS. Numerically converged results can be obtained to much lower infall particle number, if galaxies are followed even after their associated subhalos have been tidally disrupted, as in most recent semi-analytic galaxy f ormation simulations. This allows robust comparison between simulation and observation over a wider dynamic range in mass than for a SHAM analysis which ignores such “orphan” galaxies.