A gradient based method for modeling baryons and matter in halos of fast simulations
A gradient based method for modeling baryons and matter in halos of fast simulations
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DOI：
10.1088/1475-7516/2018/11/009
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发表时间：
2018-04
影响因子：
6.4
通讯作者：
B. Dai;Yu Feng;U. Seljak
中科院分区：
文献类型：
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作者：
B. Dai;Yu Feng;U. Seljak
使用少量时间步长的快速N体PM模拟，如FastPM或COLA，在模拟银河系统计数据方面取得了显著的成功，但它们缺乏小尺度的力分辨率和长时间步长，无法给出准确的晕物质轮廓或物质功率谱。高分辨率N体模拟可以改进这一点，但缺乏重子效应，只有在流体模拟中才能适当地包括重子效应。在这里，我们提出了一种方案，以校准快速模拟，以模拟水动力模拟或高分辨率N体模拟的精度。该方案基于模拟短程作用力的有效引力势的梯度下降，或模拟气体流体动力学和反馈的有效热焓的梯度下降。该方案快速且可微，可以作为后处理步骤并入任何模拟中。它给出了几个重子反馈和暗物质模拟的物质功率谱的非常好的结果，并给出了改进的暗物质晕轮廓。该方案甚至能够发现较大的亚晕，并增加了快速模拟与高分辨率N体或流体模拟之间的相关系数。它还可用于将重子效应添加到高分辨率N体模拟中。虽然该方法有可以在各种模拟中校准的自由参数，但它们也可以被视为描述重子效应的天体物理干扰参数，在数据分析过程中可以忽略这些参数。在这个观点中，这些参数可以被视为重子效应的有效的参数化。
Fast N-body PM simulations with a small number of time steps such as FastPM or COLA have been remarkably successful in modeling the galaxy statistics, but their lack of small scale force resolution and long time steps cannot give accurate halo matter profiles or matter power spectrum. High resolution N-body simulations can improve on this, but lack baryonic effects, which can only be properly included in hydro simulations. Here we present a scheme to calibrate the fast simulations to mimic the precision of the hydrodynamic simulations or high resolution N-body simulations. The scheme is based on a gradient descent of either effective gravitational potential, which mimics the short range force, or of effective enthalpy, which mimics gas hydrodynamics and feedback. The scheme is fast and differentiable, and can be incorporated as a post-processing step into any simulation. It gives very good results for the matter power spectrum for several of the baryonic feedback and dark matter simulations, and also gives improved dark matter halo profiles. The scheme is even able to find the large subhalos, and increase the correlation coefficient between the fast simulations and the high resolution N-body or hydro simulations. It can also be used to add baryonic effects to the high resolution N-body simulations. While the method has free parameters that can be calibrated on various simulations, they can also be viewed as astrophysical nuisance parameters describing baryonic effects that can be marginalized over during the data analysis. In this view these parameters can be viewed as an efficient parametrization of baryonic effects.