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arXiv 2108.11565astro-ph.GAastro-ph.CO
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宇宙网中星系性质和晕形成时间之间的联系

Connections between galaxy properties and halo formation time in the cosmic web

Youcai Zhang, Xiaohu Yang, Hong Guo

摘要:

通过将Sloan数字巡天(SDSS)中的星系与ELUCID模拟中的暗晕联系起来,研究了暗晕形成时间与星系性质的关系,以及星系性质对宇宙网环境的依赖性。我们发现,中央和卫星subhalo有不同的形成时间,卫星subhalo比中央subhalo在固定的质量。在固定质量下,星系恒星与次晕的质量比是次晕形成时间的一个很好的代理,并且随着次晕形成红移的增加而增加,特别是对于大质量星系。次晕的形成时间取决于宇宙网的环境。对于中心的次晕,有一个特征性的次晕质量$\sim 10^{12} \msun$,低于该质量的次晕在结中比在丝、片或空隙中的相同质量的次晕更老,而高于该质量的次晕则相反。恒星-晕质量比的宇宙网环境依赖性与晕形成时间的宇宙网环境依赖性相似。对于中心,有一个特征性的次晕质量$\sim 10^{12} \msun$,低于这个质量,恒星与次晕的质量比在结中比在细丝、薄片和空洞中高,高于这个质量,它就反转了。结中的镓在低于$10^{12} \msun$时颜色较红,而高于$10^{12} \msun$时,环境依赖性消失。卫星分数强烈依赖于宇宙网环境,从结到丝到片到空,特别是对于低质量星系。

英文摘要:

By linking galaxies in Sloan Digital Sky Survey (SDSS) to subhaloes in the ELUCID simulation, we investigate the relation between subhalo formation time and the galaxy properties, and the dependence of galaxy properties on the cosmic web environment. We find that central and satellite subhaloes have different formation time, where satellite subhaloes are older than central subhaloes at fixed mass. At fixed mass, the galaxy stellar-to-subhalo mass ratio is a good proxy of the subhalo formation time, and increases with the subhalo formation redshifts, especially for massive galaxies. The subhalo formation time is dependent on the cosmic web environment. For central subhaloes, there is a characteristic subhalo mass of $\sim 10^{12} \msun$, below which subhaloes in knots are older than subhaloes of the same mass in filaments, sheets, or voids, while above which it reverses. The cosmic web environmental dependence of stellar-to-subhalo mass ratio is similar to that of the subhalo formation time. For centrals, there is a characteristic subhalo mass of $\sim 10^{12} \msun$, below which the stellar-to-subhalo mass ratio is higher in knots than in filaments, sheets and voids, above which it reverses. Galaxies in knots have redder colors below $10^{12} \msun$, while above $10^{12} \msun$, the environmental dependence vanishes. Satellite fraction is strongly dependent on the cosmic web environment, and decreases from knots to filaments to sheets to voids, especially for low-mass galaxies.

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