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arXiv 1209.0463astro-ph.CO
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从透镜看晕与星系的关系

Looking at the relation between haloes and galaxies under the lens

Eyal Neistein, Sadegh Khochfar

摘要:

我们使用经验的方法来模拟恒星质量的星系根据其主机暗物质晕和subhaloes('HASH'),其中每个星系居住在一个subhalo从一个大的N体宇宙学模拟。利用弱透镜信号(WL)、两点自关联函数(CF)和星系的恒星质量函数(SMF)研究了暗晕与星系的质量关系。我们的方法是基于模拟直接从宇宙学模拟的透镜信号,因此应该是更准确的比其他方法的基础上分析晕模型。我们发现,WL不提供一个强有力的约束MR,允许超过10个因素的自由中央星系的subhalo质量,对于一个给定的恒星质量。卫星星系的自由度要大得多,对卫星星系的比例(0.05-0.8)提供了非常差的限制。当同时使用SMF和WL作为约束时,这些结果没有显著修改。我们发现,对于最大质量的星系,观测约束的基础上的CF与0.1德克斯的错误,相当于0.05德克斯的错误在WL。对于中低质量星系,WL和CF以不同的方式约束MR。虽然WL目前在这些质量上没有增加太多信息,但它有可能在未来使用更精确的测量时发挥重要作用。这里发现的模型不匹配同时观察到的CF和WL信号,并显示出有限的能力,以匹配WL和SMF。我们怀疑这部分是由于这里假设的宇宙学模型,因此我们在大部分工作中采用了模拟WL信号。与文献中以前的模型相比,这里提出的方法可能更一般,因为它揭示了一组给定的观测约束的更大范围的解决方案。

英文摘要:

We use an empirical approach to model the stellar mass of galaxies according to their host dark-matter haloes and subhaloes ('HASH'), where each galaxy resides in a subhalo taken from a large N-body cosmological simulation. This approach allows us to study the mass relation between subhaloes and galaxies (MR) using: the weak lensing signal (WL), the two point auto-correlation function (CF), and the stellar mass function of galaxies (SMF). Our method is based on modeling the lensing signal directly from the cosmological simulation, and should thus be more accurate than other methods based on analytic halo models. We find that the WL does not provide a strong constraint on the MR, allowing for more than a factor of 10 freedom in the subhalo mass of central galaxies, for a given stellar mass. The freedom for satellite galaxies is much larger, providing a very poor constraint on the fraction of satellite galaxies (0.05-0.8). These results are not significantly modified when using both the SMF and WL as constraints. We show that for the most massive galaxies, observational constraints based on the CF with 0.1 dex errors, are equivalent to 0.05 dex error in the WL. For intermediate and low mass galaxies the WL and CF constrain the MR in a different way. Although the WL is currently not adding much information at these masses, it has the potential of being important using future, more accurate measurements. The models found here do not match simultaneously the observed CF and WL signals, and show a limited ability to match the WL & SMF. We suspect that this is partially due to the cosmological model assumed here and we therefore adopt a mock WL signal through most of this work. In comparison to previous models in the literature, the method presented here is probably more general, as it reveals a larger range of solutions for a given set of observational constraints [abridged].

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