The evolution of galaxy intrinsic alignments in the MassiveBlackII universe
The evolution of galaxy intrinsic alignments in the MassiveBlackII universe
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DOI：
10.1093/mnras/stz3240
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发表时间：
2019-05
影响因子：
4.8
通讯作者：
A. Bhowmick;Yingzhang Chen;Ananth Tenneti;T. Di Matteo-T.-Di Matteo-1392893525;R. Mandelbaum
中科院分区：
文献类型：
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作者：
A. Bhowmick;Yingzhang Chen;Ananth Tenneti;T. Di Matteo-T.-Di Matteo-1392893525;R. Mandelbaum
我们研究了大质量黑洞（MBII）模拟中星系本征排列（IAs）的红移演化。我们选择了位于z = 0.6的固定亚晕质量切割（$M_h\gt 10^{11,12,13}\,\mathrm{M}_{\odot }\, h^{-1}$）以上的星系样本，并沿着它们的合并树追踪它们的祖先到z = 3。z = 0.6星系的暗物质成分比它们的祖先更球形，而恒星物质成分往往比它们的祖先更不球形。星系-亚晕失调角的分布在～ 10°处达到峰值，随时间的推移略有增加。星系的椭圆-方向（ED）相关振幅ω(r)的演化（量化了星系优先指向周围物质超密度的趋势）是由潜在暗物质（DM）亚晕对场物质密度的排列演化以及星系与它们的DM亚晕之间的排列演化决定的。在$\sim 1~\mathrm{Mpc}\, h^{-1}$尺度上，DM亚晕与物质超密度之间的对齐随着时间的推移而被抑制，而星系与DM亚晕之间的对齐则被增强。这些相互竞争的趋势导致了$\sim 1~\mathrm{Mpc}\, h^{-1}$星系ω(r)的复杂红移演化。在$\gt 1~\mathrm{Mpc}\, h^{-1}$尺度上，DM亚晕与物质过密度之间的排列没有显著的演化；因此，星系-亚晕失调的演化导致星系的ω(r)在$\gt 1~\mathrm{Mpc}\, h^{-1}$尺度上从z = 3增加到0.6，增加了约4倍。相互竞争的物理效应之间的平衡取决于尺度，导致在更小的尺度上得出不同的结论（$\sim 0.1~\mathrm{Mpc}\, h^{-1}$）。
We investigate the redshift evolution of the intrinsic alignments (IAs) of galaxies in the MassiveBlackII (MBII) simulation. We select galaxy samples above fixed subhalo mass cuts ($M_h\gt 10^{11,12,13}\,\mathrm{M}_{\odot }\, h^{-1}$) at z = 0.6 and trace their progenitors to z = 3 along their merger trees. Dark matter components of z = 0.6 galaxies are more spherical than their progenitors while stellar matter components tend to be less spherical than their progenitors. The distribution of the galaxy–subhalo misalignment angle peaks at ∼10 deg with a mild increase with time. The evolution of the ellipticity–direction (ED) correlation amplitude ω(r) of galaxies (which quantifies the tendency of galaxies to preferentially point towards surrounding matter overdensities) is governed by the evolution in the alignment of underlying dark matter (DM) subhaloes to the matter density of field, as well as the alignment between galaxies and their DM subhaloes. At scales $\sim 1~\mathrm{Mpc}\, h^{-1}$, the alignment between DM subhaloes and matter overdensity gets suppressed with time, whereas the alignment between galaxies and DM subhaloes is enhanced. These competing tendencies lead to a complex redshift evolution of ω(r) for galaxies at $\sim 1~\mathrm{Mpc}\, h^{-1}$. At scales $\gt 1~\mathrm{Mpc}\, h^{-1}$, alignment between DM subhaloes and matter overdensity does not evolve significantly; the evolution of the galaxy–subhalo misalignment therefore leads to an increase in ω(r) for galaxies by a factor of ∼4 from z = 3 to 0.6 at scales $\gt 1~\mathrm{Mpc}\, h^{-1}$. The balance between competing physical effects is scale dependent, leading to different conclusions at much smaller scales ($\sim 0.1~\mathrm{Mpc}\, h^{-1}$).