打破大质量星系中发光物质和暗物质之间的联系
Breaking down the link between luminous and dark matter in massive galaxies
摘要：
本文研究了帕洛玛天文台宽视场红外巡天中恒星质量M*>10^10Msol的星系在红移0.4<z<2.0时的成团情况。我们研究了这些恒星质量选定的样本的集群作为红移和恒星质量的函数的属性，并发现，具有高恒星质量的星系有一个渐进的更高的集群强度比星系具有较低的恒星质量。我们还发现，在一个固定的恒星质量范围内的星系有一个较高的集群强度在较高的红移。我们进一步估计这些恒星质量的选定星系的暗物质晕的平均总质量。对于我们样本中的所有星系，恒星质量与总质量的比值总是低于普适重子质量分数，恒星质量与总质量的比值与中心星系的晕质量密切相关，因此质量更大的晕以恒星的形式包含更低的质量分数。剩余的重子质量部分包含在这些晕中的卫星星系内的恒星中，并作为弥漫的热和温暖的气体。我们还发现，在一个固定的恒星质量，恒星的总质量比增加在较低的红移。这表明，恒星质量固定的星系形成较晚的低质量暗物质晕，而较早的大质量晕。我们将此解释为“光环缩小”效应。
英文摘要：
We present a study on the clustering of a stellar mass selected sample of galaxies with stellar masses M*>10^10Msol at redshifts 0.4<z<2.0, taken from the Palomar Observatory Wide-field Infrared Survey. We examine the clustering properties of these stellar mass selected samples as a function of redshift and stellar mass, and find that galaxies with high stellar masses have a progressively higher clustering strength than galaxies with lower stellar masses. We also find that galaxies within a fixed stellar mass range have a higher clustering strength at higher redshifts. We further estimate the average total masses of the dark matter haloes hosting these stellar-mass selected galaxies. For all galaxies in our sample the stellar-mass-to-total-mass ratio is always lower than the universal baryonic mass fraction and the stellar-mass-to-total-mass ratio is strongly correlated with the halo masses for central galaxies, such that more massive haloes contain a lower fraction of their mass in the form of stars. The remaining baryonic mass is included partially in stars within satellite galaxies in these haloes, and as diffuse hot and warm gas. We also find that, at a fixed stellar mass, the stellar-to-total-mass ratio increases at lower redshifts. This suggests that galaxies at a fixed stellar mass form later in lower mass dark matter haloes, and earlier in massive haloes. We interpret this as a `halo downsizing' effect.
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