EVOLUTION OF THE GALAXY–DARK MATTER CONNECTION AND THE ASSEMBLY OF GALAXIES IN DARK MATTER HALOS
EVOLUTION OF THE GALAXY–DARK MATTER CONNECTION AND THE ASSEMBLY OF GALAXIES IN DARK MATTER HALOS
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DOI：
10.1088/0004-637x/752/1/41
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发表时间：
2011-10
期刊：
影响因子：
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通讯作者：
Xiaohu Yang;H. Mo;F. V. D. Bosch;Youcai Zhang;Jiaxin Han
中科院分区：
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作者：
Xiaohu Yang;H. Mo;F. V. D. Bosch;Youcai Zhang;Jiaxin Han
我们提出了一种新模型来描述整个宇宙时间中的星系-暗物质联系，与流行的次晕丰度匹配技术不同，该模型是自洽的，因为它考虑了以下事实：(1)次晕在不同时间吸积，(2)卫星星系的特性可能在吸积后演化。利用对 z ∼ 4 范围内的星系恒星质量函数（SMF）的观测、从斯隆数字巡天星系群目录获得的 z ∼ 0.1 处的条件 SMF，以及 z ∼ 0.1 处星系的两点相关函数（2PCF）作为恒星质量的函数，我们限制了从 z ∼ 4 至今的整个宇宙历史中星系与暗物质晕之间的关系。然后用这种关系来预测暗物质晕（中央星系、卫星星系和晕星）内不同恒星质量成分的中值组装历史。我们还对高 z 星系的 2PCF 作为恒星质量的函数进行了预测。我们的主要发现如下：（1）我们的模型合理地拟合了观测不确定性内的所有数据，表明ΛCDM一致性宇宙学与有关整个宇宙时间的星系群体的各种数据是一致的。 (2) 在低z处，中心星系的恒星质量随着晕质量的增加而增加，在质量端和低质量端分别为M0.3和M≳4.0。比率 M*、c/M 显示晕质量 M ∼ 1011.8 h−1 M☉ 处的最大值为 ∼0.03，远低于通用重子分数 (∼0.17)。在较高的红移处，M* 的最大值，c/M 仍接近 ∼0.03，但会转向更高的晕质量。 (3) 推断的卫星星系破裂的时间尺度与其子晕的动力摩擦时间尺度大致相同。 (4) 中心星系的恒星质量组装历史与其主晕的组装历史完全脱钩；比率 M*, c/M 最初随时间快速增加，直到晕质量达到 ∼1012 h−1 M☉，此时 M*, c/M ∼ 0.03。一旦 M ≳ 1012 h−1 M☉，M*、c 几乎没有增长，导致 M*、c/M 比率下降。在银河系 (MW) 大小的光环中，超过一半的中心恒星质量聚集在 z ≲ 0.5 处。 (5) 在低质量晕中，卫星星系的吸积对其中心星系的形成贡献很小，这表明它们的大部分恒星必定是在原位形成的。在大质量晕中，中心星系一半以上的恒星质量必须就地形成，卫星的吸积只有在 z ≲ 2 时才会变得显着。 (6) 晕恒星的总质量是大质量晕中中央星系的两倍以上，但不到 MW 级晕中 M*、c 的 10%。 (7) 小尺度星系的 2PCF 包含有关卫星星系演化的重要信息，预计高 z 值比低 z 值陡峭得多，特别是对于质量较大的星系。我们讨论了关于 ΛCDM 宇宙学中星系的形成和演化的研究结果的各种含义。
We present a new model to describe the galaxy–dark matter connection across cosmic time, which unlike the popular subhalo abundance-matching technique is self-consistent in that it takes account of the facts that (1) subhalos are accreted at different times and (2) the properties of satellite galaxies may evolve after accretion. Using observations of galaxy stellar mass functions (SMFs) out to z ∼ 4, the conditional SMF at z ∼ 0.1 obtained from Sloan Digital Sky Survey galaxy group catalogs, and the two-point correlation function (2PCF) of galaxies at z ∼ 0.1 as a function of stellar mass, we constrain the relation between galaxies and dark matter halos over the entire cosmic history from z ∼ 4 to the present. This relation is then used to predict the median assembly histories of different stellar mass components within dark matter halos (central galaxies, satellite galaxies, and halo stars). We also make predictions for the 2PCFs of high-z galaxies as function of stellar mass. Our main findings are the following: (1) Our model reasonably fits all data within the observational uncertainties, indicating that the ΛCDM concordance cosmology is consistent with a wide variety of data regarding the galaxy population across cosmic time. (2) At low-z, the stellar mass of central galaxies increases with halo mass as M0.3 and M≳ 4.0 at the massive and low-mass ends, respectively. The ratio M*, c/M reveals a maximum of ∼0.03 at a halo mass M ∼ 1011.8 h−1 M☉, much lower than the universal baryon fraction (∼0.17). At higher redshifts the maximum in M*, c/M remains close to ∼0.03, but shifts to higher halo mass. (3) The inferred timescale for the disruption of satellite galaxies is about the same as the dynamical friction timescale of their subhalos. (4) The stellar mass assembly history of central galaxies is completely decoupled from the assembly history of its host halo; the ratio M*, c/M initially increases rapidly with time until the halo mass reaches ∼1012 h−1 M☉, at which point M*, c/M ∼ 0.03. Once M ≳ 1012 h−1 M☉, there is little growth in M*, c, causing the ratio M*, c/M to decline. In Milky Way (MW)-sized halos more than half of the central stellar mass is assembled at z ≲ 0.5. (5) In low-mass halos, the accretion of satellite galaxies contributes little to the formation of their central galaxies, indicating that most of their stars must have formed in situ. In massive halos more than half of the stellar mass of the central galaxy has to be formed in situ, and the accretion of satellites can only become significant at z ≲ 2. (6) The total mass in halo stars is more than twice that of the central galaxy in massive halos, but less than 10% of M*, c in MW-sized halos. (7) The 2PCFs of galaxies on small scales hold important information regarding the evolution of satellite galaxies, which at high-z is predicted to be much steeper than at low-z, especially for more massive galaxies. We discuss various implications of our findings regarding the formation and evolution of galaxies in a ΛCDM cosmology.