基于投影几率的星系对统计研究方法对COSMOS巡天的新应用
发布时间：2019-05-20 02:37
【摘要】：在我们的研究中提出了一个新的统计方法来研究COSMOS巡天中的星系对比例演化,首先我们利用两星系的投影几率作为判断星系对的标准建立一个间接的星系对样本,然后用在空间上随机分布的星系模拟真实空间的中的投影星系对,并从样本的结果中扣除模拟中得到的投影星系对的结果。在我们的工作中发现在rprsc p范围存在较严重的屏蔽效应,rsc p的值在不同的红移段是不一样的,大致在～15 h-175kpc到～25 h-175kpc之间。我们从样本中抽取出统计上投影距离(rp)落在～20 h-175kpc到～30 h-175kpc范围内的星系对得到一个星系对的取样样本,从经验上避免了屏蔽效应在高红移星系对统计中的影响。通过与邻近宇宙中的CPG星系对样本[1 3]的统计比较发现我们取样的星系对样本与CPG样本有相似的rp分布,说明我们取样的星系对样本是CPG的演化对应体。基于对CPG的演化对应体的分析,我们得到一个星系对比例的演化关系(1+z)m,其中m的值为0.93±0.20,它表明星系对比例随着红移的增加有一个中等快速的增加。同时我们也发现运用SExtractor软件得到的空间COSMOS巡天的星系列表中在高红移处存在较严重的过度分化,空间的星系目录在rprsc p范围得到的星系对很大一部分是过度分化的星系。所以我们对一些早期的研究得到的星系对比例有快速演化m≈2.2-3.1的结论提出严重的质疑。另外我们的研究发现孤立的星系对周围的物理环境存在一个比较明显且复杂的演化,所以星系对比例的演化率并不能直接的转化为星系的并合速率,因为受到星系对周围物理环境的影响,星系对的演化时标τm可能存在复杂的演化,在不同的红移处τm的值很可能不是一致的,星系对比例的演化转化为星系并合率时应该包含τm在不同红移段的变化。我们的研究对以后的高红移星系对的研究也提出了一些新的有趣的且重要的问题,屏蔽效应对星系对选择的主要影响和星系对周围物理环境对星系对演化时标τm的影响。
[Abstract]:In our study, a new statistical method is proposed to study the proportional evolution of galaxy pairs in the COSMOS survey. First, we use the projection probability of the two systems as the criterion for judging the galaxy pair to establish an indirect galaxy pair sample. Then the projected galaxy pairs in real space are simulated by randomly distributed galaxy pairs in space, and the projected galaxy pairs obtained in the simulation are deducted from the sample results. In our work, it is found that there is a serious shielding effect in the range of rprsc p, the value of, rsc p is different in different red shift segments, which is between ~ 15 h-175kpc and ~ 25 h-175kpc. A sampling sample of a galactic pair with a statistical projection distance of ~ 20 h-175kpc to ~ 30 h-175kpc is obtained from the sample, which avoids the influence of shielding effect on the statistics of highly red-shifted galaxy. The sample is selected from the sample and the sampling sample of galaxy pair with statistical projection distance from ~ 20 h-175kpc to ~ 30 h-175kpc is obtained, which avoids the influence of shielding effect on the statistics of highly red-shifted galaxy. Through the statistical comparison with the CPG galaxy pair sample [1 鈮，
本文编号：2481274
[Abstract]:In our study, a new statistical method is proposed to study the proportional evolution of galaxy pairs in the COSMOS survey. First, we use the projection probability of the two systems as the criterion for judging the galaxy pair to establish an indirect galaxy pair sample. Then the projected galaxy pairs in real space are simulated by randomly distributed galaxy pairs in space, and the projected galaxy pairs obtained in the simulation are deducted from the sample results. In our work, it is found that there is a serious shielding effect in the range of rprsc p, the value of, rsc p is different in different red shift segments, which is between ~ 15 h-175kpc and ~ 25 h-175kpc. A sampling sample of a galactic pair with a statistical projection distance of ~ 20 h-175kpc to ~ 30 h-175kpc is obtained from the sample, which avoids the influence of shielding effect on the statistics of highly red-shifted galaxy. The sample is selected from the sample and the sampling sample of galaxy pair with statistical projection distance from ~ 20 h-175kpc to ~ 30 h-175kpc is obtained, which avoids the influence of shielding effect on the statistics of highly red-shifted galaxy. Through the statistical comparison with the CPG galaxy pair sample [1 鈮，
本文编号：2481274
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