Wings局域团簇中的超稠密块状半导体
Superdense Massive Galaxies in Wings Local Clusters
摘要：
z>1的大质量静止星系被发现具有小的物理尺寸，因此是超密度的。已经提出了几种机制，包括小合并，用于从高z到低z增加星系大小。我们在X射线选择星系团的宽视场近星系团巡天（WINGS）中寻找0.04<z<0.07的超致密大质量星系。我们发现了一个重要的人口超致密的大质量星系的质量和大小相媲美的观察高红移。它们大约占所有星系团中质量大于3 × 10^10 Msol的22%，大部分是S 0星系，中值有效半径<Re>=1.61+/-0.29 kpc，中值Sersic指数<n>= 3.0+/-0.6，非常古老的恒星星族，中值质量加权年龄为12.1+/-1.3Gyr。我们计算出本星系团中超致密星系的数密度为2.9 × 10 ^-2 Mpc ^-3，在z = 0.04和z = 0.07之间的整个同向运动体积中，数密度的硬性下限为1.3 × 10 ^-5 Mpc ^-3。我们发现质量，有效半径和光度加权年龄之间的关系，在我们的星系团，这可以模仿声称的半径与红移的演变，如果没有适当考虑。我们将我们的数据与光谱高z调查进行比较，发现当考虑恒星质量时，与当地WINGS星系大小的一致性达到z~2，而与唯一的光谱z>2研究存在3倍的差异。相比之下，有强有力的证据表明，与WINGS中的类似质量星系（即BCGs）相比，M*>4x10^11Msol的最大质量星系的半径发生了很大的演化。
英文摘要：
Massive quiescent galaxies at z>1 have been found to have small physical sizes, hence to be superdense. Several mechanisms, including minor mergers, have been proposed for increasing galaxy sizes from high- to low-z. We search for superdense massive galaxies in the WIde-field Nearby Galaxy-cluster Survey (WINGS) of X-ray selected galaxy clusters at 0.04<z<0.07. We discover a significant population of superdense massive galaxies with masses and sizes comparable to those observed at high redshift. They approximately represent 22% of all cluster galaxies more massive than 3x10^10Msol, are mostly S0 galaxies, have a median effective radius <Re> =1.61+/-0.29kpc, a median Sersic index <n> = 3.0+/-0.6, and very old stellar populations with a median mass-weighted age of 12.1+/-1.3Gyr. We calculate a number density of 2.9x10^-2Mpc^-3 for superdense galaxies in local clusters, and a hard lower limit of 1.3x10^-5Mpc^-3 in the whole comoving volume between z = 0.04 and z = 0.07. We find a relation between mass, effective radius and luminosity-weighted age in our cluster galaxies, which can mimic the claimed evolution of the radius with redshift, if not properly taken into account. We compare our data with spectroscopic high-z surveys and find that -when stellar masses are considered- there is consistency with the local WINGS galaxy sizes out to z~2, while a discrepancy of a factor of 3 exists with the only spectroscopic z>2 study. In contrast, there is strong evidence for a large evolution in radius for the most massive galaxies with M*>4x10^11Msol compared to similarly massive galaxies in WINGS, i.e. the BCGs.
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