后发座星系团视线的非常深的光谱学:探索新的领域
Very deep spectroscopy of the Coma cluster line of sight: exploring new territories
摘要:
环境效应对星系团有重要的影响,但在非常微弱的星等(R>21)的研究几乎完全基于成像。我们在这里提出了一个非常深的光谱调查星系的视线后发座,根据红移获得的VLT/VIMOS的715个星系在前所未有的星等范围21<R<23(绝对星等-14至-12)。我们确认了Adami等人(2005年a)在昏迷中发现的亚结构,并发现了三个新的亚结构。我们在Coma后面检测到许多组:z~0.5的大型结构,SDSS长城,以及z~0.054的大型且非常年轻的结构。这些结构解释了Gavazzi等人(2009)最近弱透镜分析得出的质量图。矮星系的轨道可能是各向异性的和径向的,并且可能起源于径向落入星系团的场星系。后发座矮星系的光谱特征表明,红色或吸收线星系具有较大的恒星质量,比蓝色或发射线星系更古老。R <22 galaxies show less prominent absorption lines than R>22星系。对于场星系来说,这种趋势就不那么明显了,这表明部分暗淡的后发星系可能是在NGC 4911星系团坠落后从场星系中注入的。我们列出了五个超紧凑矮星系候选者。我们还在全球范围内证实了我们以前的星系光度函数的光谱结果,并发现矮星系遵循类似于明亮星系绘制的红色序列。后发座中有大量的矮星系,它们是沿着暗条落入星系团的部分场星系。
英文摘要:
Environmental effects have an important influence on cluster galaxies, but studies at very faint magnitudes (R>21) are almost exclusively based on imaging. We present here a very deep spectroscopic survey of galaxies on the line of sight to Coma, based on redshifts obtained with VLT/VIMOS for 715 galaxies in the unprecedented magnitude range 21<R<23 (absolute magnitude -14 to -12). We confirm the substructures previously identified in Coma by Adami et al. (2005a), and identify three new ones. We detect many groups behind Coma: a large structure at z~0.5, the SDSS Great Wall, and a large and very young structure at z~0.054. These structures account for the mass maps derived from a recent weak lensing analysis by Gavazzi et al. (2009). The orbits of dwarf galaxies are probably anisotropic and radial, and could originate from field galaxies radially falling into the cluster. Spectral characteristics of Coma dwarf galaxies show that red or absorption line galaxies have larger stellar masses and are older than blue or emission line galaxies. R<22 galaxies show less prominent absorption lines than R>22 galaxies. This trend is less clear for field galaxies, suggesting that part of the faint Coma galaxies could have been recently injected from the field following the NGC 4911 group infall. We present a list of five Ultra Compact Dwarf galaxy candidates. We also globally confirm spectroscopically our previous results on the galaxy luminosity functions and find that dwarf galaxies follow a red sequence similar to that drawn by bright galaxies. Dwarf galaxies are very abundant in Coma, and are partly field galaxies that have fallen onto the cluster along filaments.
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