A MULTIWAVELENGTH STUDY OF A SAMPLE OF 70 μm SELECTED GALAXIES IN THE COSMOS FIELD. II. THE ROLE OF MERGERS IN GALAXY EVOLUTION-猫眼课题宝

DOI：

10.1088/0004-637x/721/1/98

发表时间：

2010-06

期刊：

The Astrophysical Journal

影响因子：

通讯作者：

中科院分区：

其他

文献类型：

作者：

J. Kartaltepe;D. Sanders;E. Floc’h;E. Floc’h;D. Frayer;H. Aussel;S. Arnouts;O. Ilbert;M. Salvato;N. Scoville;J. Surace;Lin Yan;P. Capak;K. Caputi;C. Carollo;P. Cassata;F. Civano;G. Hasinger;A. Koekemoer;O. Fèvre;S. Lilly;C. T. Liu;H. McCracken;E. Schinnerer;V. Smolčić;Y. Taniguchi;D. Thompson;J. Trump;V. Baldassare;S. Fiorenza

我们分析了 COSMOS 场中 1503 个 70 μm 选定星系的大样本的形态特性，红移范围跨越 0.01 1012 L☉)，高达~50%。我们还发现，随着 LIR，螺旋的比例急剧下降。较小的合并可能在提高低光度光源的红外光度方面发挥了作用（LIR 1 很难分类，并且受到带通偏移的影响；因此，这些数字只能被认为是下限。在 z 1 时，主要合并的比例较低，但对于 ULIRG 来说至少为 30%–40%。在将我们的视觉分类与几种自动分类技术进行比较时，我们发现普遍一致；然而，已识别的合并的比例为由于自动分类方法仅对重大合并的某些时间尺度敏感，尽管总体形态趋势与本地 (U)LIRG 观察到的结果一致，但主要合并的比例略低于本地观察到的，部分原因是难以识别高红移处的合并特征。我们的样本中星系的 U − V 颜色分布在绿谷 (<U − V> = 1.1)，在蓝色和蓝色处分布较大。我们认为，考虑到观测到的主要富含气体合并的数量以及在 (U)LIRG 阶段可观测到的相对较短的时间尺度，观测到的大块椭圆星系 (<1012 M☉) 的红色序列完全由富含气体的主要合并形成是合理的。

We analyze the morphological properties of a large sample of 1503 70 μm selected galaxies in the COSMOS field spanning the redshift range 0.01 1012 L☉) being up to ∼50%. We also find that the fraction of spirals drops dramatically with LIR. Minor mergers likely play a role in boosting the infrared luminosity for sources with low luminosities (LIR 1 being difficult to classify and subject to the effects of bandpass shifting; therefore, these numbers can only be considered lower limits. At z 1, the fraction of major mergers is lower, but is at least 30%–40% for ULIRGs. In a comparison of our visual classifications with several automated classification techniques we find general agreement; however, the fraction of identified mergers is underestimated due to automated classification methods being sensitive to only certain timescales of a major merger. Although the general morphological trends agree with what has been observed for local (U)LIRGs, the fraction of major mergers is slightly lower than seen locally. This is in part due to the difficulty of identifying merger signatures at high redshift. The distribution of the U − V color of the galaxies in our sample peaks in the green valley (〈U − V〉 = 1.1) with a large spread at bluer and redder colors and with the major mergers peaking more strongly in the green valley than the rest of the morphological classes. We argue that, given the number of major gas-rich mergers observed and the relatively short timescale that they would be observable in the (U)LIRG phase, it is plausible for the observed red sequence of massive ellipticals (<1012 M☉) to have been formed entirely by gas-rich major mergers.

A MULTIWAVELENGTH STUDY OF A SAMPLE OF 70 μm SELECTED GALAXIES IN THE COSMOS FIELD. II. THE ROLE OF MERGERS IN GALAXY EVOLUTION

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