重子物质对暗物质晕形状和角动量的影响  

The Effects of Baryons on the Shapes and Angular Momentum of Dark Matter Halos

作　　者：张瑶瑶 戴才萍[1,3] ZHANG Yao-yao;DAI Cai-ping(Purple Mountain Observatory,Chinese Academy of Sciences,Nanjing 210023;School of Astronomy and Space Science,University of Science and Technology of China,Hefei 230026;National Basic Discipline Public Science Data Center,Beijing 100190)

机构地区：[1]中国科学院紫金山天文台,南京210023 [2]中国科学技术大学天文与空间科学学院,合肥230026 [3]国家基础学科公共科学数据中心,北京100190

出　　处：《天文学报》2021年第6期79-93,共15页Acta Astronomica Sinica

基　　金：国家基础学科公共科学数据中心(NBSDC)的宇宙学模拟数据库(CSD)和中国科学院对其的基金项目(202000000088)资助。

摘　　要：利用高精度大样本的冷暗物质(Λcold dark matter,ΛCDM)宇宙学数值模拟的数据,对重子物质如何影响暗物质晕的形状和角动量进行了研究.使用了3种数值模拟数据,纯暗物质模拟、含辐射冷却、恒星形成和动力学超新星反馈的模拟,包含活动星系核反馈效应的恒星形成模拟.对这3种模拟,还进行了不同红移处的比较.主要结果如下.重子物理过程会改变暗物质晕的质量分布,特别是有活动星系核反馈机制的情况下.比如,活动星系核反馈会减少大质量暗物质晕的形成.随着宇宙的演化,暗物质晕的空间形态逐渐由扁变圆.重子物质的存在会加速暗物质晕形状的变化过程,而且会使暗物质晕形状变得更圆.但是活动星系核的反馈会对这一加速效应产生抑制.重子物质对暗物质晕的影响与暗物质晕的质量和半径都存在一定的依赖性.暗物质晕的质量越大,它会呈现更扁的形态.同时,重子物质对任意质量的暗物质晕或暗物质晕在任意半径处的变圆均有一定的促进作用,尽管活动星系核反馈会抑制这一促进作用.特别是对于暗物质晕在0.2–0.6倍维里半径处的形状,重子物质的影响尤为明显.此外,重子物质的存在会对暗物质晕的角动量产生显著影响,它会增大暗物质的角动量.暗物质晕的自旋参数与质量无相关性,但是与暗物质晕的半径存在一定的相关性.Adopting the data of high-precision and large-sampleΛcold dark matter(ΛCDM)cosmological simulations,the effects of baryonic processes on the shapes and angular momentum of dark matter(DM)halos have been investigated.Here,the data of three numerical simulations at three different redshifts were used,i.e.,dark matter only(DMO),radiative cooling,star formation,and kinetic supernovae feedback(CSF),and CSF simulation accompanying with active galactic nucleus(AGN)feedback.The baryonic processes can influence the halo mass function,especially in the presence of AGN feedback.However,the feedback of AGN reduces the formation of massive DM halos.As the Universe evolves,the spatial shapes of DM halos are gradually from flat to round.The baryonic processes accelerate this process as well as make DM halos more rounded,while the AGN feedback suppresses this acceleration,and this effect of baryonic processes is dependent on both the masses and radii of DM halos.The smaller masses of DM halos,the more significant effect of baryons will occur.Meanwhile,the baryonic processes contribute to the rounding process for any masses or radii of DM halos,although the AGN feedback will suppress this facilitation.In particular,the effect of baryons is particularly pronounced for the DM halos having radii at 0.2–0.6 times the virial radius.Besides,the baryonic processes have an effect on the angular momentum of DM halos,e.g.,increases the angular momentum.The spin parameter does not depend on the mass but has a certain correlation with the radius of the DM halo.

关 键 词：星系:晕 暗物质 宇宙大尺度结构 方法:数值 方法:统计 

分 类 号：P159[天文地球—天文学]