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arXiv 1003.1981astro-ph.CO
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星系光度函数随星系群性质的变化

The Variation of the Galaxy Luminosity Function with Group Properties

Aaron Robotham, Steve Phillipps, Roberto de Propris

摘要:

我们探索的星系光度函数(LF)的形状在不同质量的群体,通过创建复合LF超过大量的群体。继以前的工作使用总组光度作为质量指标,在这里,我们分裂我们的群体的多重性和估计维里(组晕)质量,并考虑红色(被动)和蓝色(恒星形成)星系分开。此外,我们利用两个不同的组目录(2 PIGG和杨等人)。以确定特定分组算法的影响,并通过LF随组中位置的变化进一步研究环境影响。我们的主要结果是,LF显示出一个陡峭的暗端的早期类型的星系作为一个功能的群体质量/多重性,与一个更受抑制的趋势(明显的,只有在高质量的群体)晚型星系。无论使用哪种分组目录,也无论广泛地说使用何种方法确定群体“质量”,作为群体质量函数的LF之间的变化都是稳健的。我们特别发现,有一个显着的赤字低质量的被动星系在低多重性群体,如在高红移星系团。此外,LF的变化似乎只发生在系统的中心区域,实际上似乎最强烈地依赖于相对于维里半径的组中的位置。最后,考虑了距离-秩星等关系。只有杨氏星系群证明了星系相对于最亮星系群成员的位置与其光度之间的相关性。2 PIGG不具有这种梯度,结论是FOF算法抑制了弱亮度-位置趋势的信号,而Yang分组算法自然增强了它。

英文摘要:

We explore the shape of the galaxy luminosity function (LF) in groups of different mass by creating composite LFs over large numbers of groups. Following previous work using total group luminosity as the mass indicator, here we split our groups by multiplicity and by estimated virial (group halo) mass, and consider red (passive) and blue (star forming) galaxies separately. In addition we utilise two different group catalogues (2PIGG and Yang et al.) in order to ascertain the impact of the specific grouping algorithm and further investigate the environmental effects via variations in the LF with position in groups. Our main results are that LFs show a steepening faint end for early type galaxies as a function of group mass/ multiplicity, with a much suppressed trend (evident only in high mass groups) for late type galaxies. Variations between LFs as a function of group mass are robust irrespective of which grouping catalogue is used, and broadly speaking what method for determining group `mass' is used. We find in particular that there is a significant deficit of low-mass passive galaxies in low multiplicity groups, as seen in high redshift clusters. Further to this, the variation in the LF appears to only occur in the central regions of systems, and in fact seems to be most strongly dependent on the position in the group relative to the virial radius. Finally, distance-rank magnitude relations were considered. Only the Yang groups demonstrated any evidence of a correlation between a galaxy's position relative to the brightest group member and its luminosity. 2PIGG possessed no such gradient, the conclusion being the FOF algorithm suppresses the signal for weak luminosity--position trends and the Yang grouping algorithm naturally enhances it.

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