Morphological Dependence of Star Formation Properties for the Galaxies in the Merging Galaxy Cluster A2255
Morphological Dependence of Star Formation Properties for the Galaxies in the Merging Galaxy Cluster A2255
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DOI：
10.1086/497390
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发表时间：
2005-08
期刊：
影响因子：
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通讯作者：
Q. Yuan;Lifang Zhao;Yanbin Yang;Z. Wen;Xu Zhou
中科院分区：
文献类型：
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作者：
Q. Yuan;Lifang Zhao;Yanbin Yang;Z. Wen;Xu Zhou
合并中的星系团A2255被斯隆数字巡天（SDSS）覆盖。根据Brinchmann等人对SDSS数据的分析，得到了184个亮成员星系的物理参数，从而可以详细研究中红移合并星系团中星系的星星形成特性。在本文中，我们进行了形态分类的基础上的SDSS成像和光谱数据和调查的形态依赖的星星形成率（SFR）的成员星系。正如我们所预料的那样，A2255晚型星系的SFR/M* 与Hα等效宽度之间存在紧密的相关性。SFR/M* 与4000 ℃连续断裂强度的相关性也得到了证实。发现早型和晚型星系的SFR/M*-M* 相关性表明，当聚集恒星质量（M*）增加时，星星形成活动趋于被抑制，且晚型星系的这种相关性更紧密、更陡峭.与场旋涡星系的质量范围相比，在A2255中只有两个M* > 1011 M的大质量晚型星系幸存下来，这表明大质量旋涡星系的气体盘可能在星系团形成过程中被潮汐剥离。此外，SFR随投影径向距离的变化很大程度上取决于星系的形态：早型星系内部SFR/M* 的下降很弱，而内部晚型星系往往比外部晚型星系具有更高的SFR/M* 值。这可能表明，由子星系团合并激发的星系尺度湍流在早型和晚型星系中可能起着不同的作用，导致E/S 0星系的星星形成活动受到抑制，而螺旋星系和不规则星系的SFR增强。
The merging cluster of galaxies A2255 is covered by the Sloan Digital Sky Survey (SDSS) survey. The physical parameters of 184 bright member galaxies derived from the SDSS data analyses by Brinchmann et al. allow a detailed study of the star formation properties of galaxies within a merging cluster at intermediate redshift. In this paper we perform a morphological classification on the basis of the SDSS imaging and spectral data and investigate the morphological dependence of the star formation rates (SFRs) for these member galaxies. As we expect, a tight correlation between the SFR normalized by stellar mass (SFR/M*) and the Hα equivalent width is found for the late-type galaxies in A2255. The correlation of SFR/M* with the continuum break strength at 4000 Å is also confirmed. A SFR/M*-M* correlation is found for both early- and late-type galaxies, indicating that the star formation activity tends to be suppressed when the assembled stellar mass (M*) increases, and this correlation is tighter and steeper for the late-type cluster galaxies. Compared with the mass range of field spiral galaxies, only two massive late-type galaxies with M* > 1011 M⊙ have survived in A2255, suggesting that the gas disks of massive spiral galaxies could have been tidally stripped during cluster formation. In addition, the SFR variation with the projected radial distance is found to be heavily dependent on galaxy morphology: the early-type galaxies have a very weak inner decrease in SFR/M*, while the inner late-type galaxies tend to have higher SFR/M* values than the outer late-type galaxies. This may suggest that the galaxy-scale turbulence stimulated by the merging of subclusters might have played different roles in early- and late-type galaxies, which leads to a suppression of the star formation activity for E/S0 galaxies and an SFR enhancement for spiral and irregular galaxies.