Environmental Effects in the Interaction and Merging of Galaxies in zCOSMOS
Environmental Effects in the Interaction and Merging of Galaxies in zCOSMOS
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zCOSMOS 中星系相互作用和合并的环境影响
DOI：
10.1088/0004-637x/762/1/43
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
et al.
中科院分区：
文献类型：
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作者：
Kampczyk;Lilly;de Ravel;Le Fevre;...;Tanaka;et al.
我们分析了在zCOSMOS-Bright 10k光谱样本中发现的红移范围0.2<；z<；1的153个紧密运动学对的环境和星系性质(形态和恒星形成历史)。校正投影效应后，密度最高的四分位数中接近的运动学对的比例是密度最低的四分位数的三倍。这意味着合并率提高了三倍，因为根据千禧年模拟的模拟目录显示，一旦对预测进行相同的修正，合并时间在很大程度上与环境无关。然后，我们检查这两个星系对中星系的形态和恒星群，将它们与在环境中仔细匹配的对照样本进行比较，以便尽可能多地消除众所周知的环境对父星系群性质的影响。一旦以这种方式适当考虑环境，我们发现，由于盘状星系的扰动，早期和晚期的形态混合与母体种群相同，但不规则星系的比例增加了50%-75%，不规则-不规则对的数量不成比例地增加了(4-8倍)。未来的干式合并，包括椭圆星系，只占所有接近的运动学对的不到5%。在最接近的恒星对中，恒星形成星系的特定恒星形成率增加了2-4倍，也有证据表明恒星爆发后星系的发生率增加。虽然对所涉及的星系来说意义重大，但与恒星对相关的“过剩”恒星形成只占母样本中整体恒星形成活动的5%左右。虽然大多数成对星系都在密度较高的环境中，但在密度较低的环境中，相互作用的影响似乎最大。通过在低密度环境中优先将更多的对引入样本，这可能会稀释对比例对环境的依赖，并可能将其他偏差引入合并的观察研究，特别是基于形态标准的合并。
We analyze the environments and galactic properties (morphologies and star formation histories) of a sample of 153 close kinematic pairs in the redshift range 0.2< z< 1 identified in the zCOSMOS-bright 10 k spectroscopic sample of galaxies. Correcting for projection effects, the fraction of close kinematic pairs is three times higher in the top density quartile than in the lowest one. This translates to a three times higher merger rate because the merger timescales are shown, from mock catalogs based on the Millennium simulation, to be largely independent of environment once the same corrections for projection are applied. We then examine the morphologies and stellar populations of galaxies in the pairs, comparing them to control samples that are carefully matched in environment so as to remove as much of the well-known effects of environment on the properties of the parent population of galaxies as possible. Once the environment is properly taken into account in this way, we find that the early–late morphology mix is the same as for the parent population, but that the fraction of irregular galaxies is boosted by 50%–75%, with a disproportionate increase in the number of irregular–irregular pairs (factor of 4–8 times), due to the disturbance of disk galaxies. Future dry mergers, involving elliptical galaxies comprise less than 5% of all close kinematic pairs. In the closest pairs, there is a boost in the specific star formation rates of star-forming galaxies of a factor of 2–4, and there is also evidence for an increased incidence of post-starburst galaxies. Although significant for the galaxies involved, the" excess" star formation associated with pairs represents only about 5% of the integrated star formation activity in the parent sample. Although most pair galaxies are in dense environments, the effects of interaction appear to be largest in the lower density environments. By preferentially bringing more pairs into the sample in lower density environments, this could dilute the dependence of pair fraction on environment and may introduce other biases into the observational study of mergers, especially those based on morphological criteria.