SDSS中

发布时间：2018-06-30 04:01

本文选题：相互作用 + 星系对　；参考：《上海师范大学》2013年硕士论文

【摘要】：星系间的相互作用及并合在星系的演化过程中起着十分重要的作用。数值模拟实验表明，星系与星系之间的相互作用会对星系内部的恒星及气体产生强烈的扰动，进而对星系的光度、颜色、形态、金属丰度及内部恒星形成活动产生重要影响。一般来说，相互作用“星系对”比场星系具有更强的恒星形成，颜色上偏蓝，形态上更趋于不规则。大量的统计研究结果也支持类似的观点。然而由于观测条件及数据的限制，不同的研究工作在“星系对”统计样本的选取及统计方法的采用上具有显著的差异，因而得到的统计研究结果也往往不完全一致。本文基于Allam（2004）的工作，从SDSS DR2的测光数据库中证认出一个大的高质量的相互作用“星系对”样本，其中包含8792对孤立的相互作用“星系对”。这些“星系对”具有投影间距小，周围没有其他干扰星系等特点。这些特点对研究相互作用对星系性质的影响十分重要。此外，本文通过收集该样本星系的各种测光数据及光谱数据，进一步建立了一个包含测光资料及光谱资料的更完善的星系样本，其中包含了2779个相互作用星系。这部分星系是本文用来做统计研究的主要星系样本，简称为光谱样本（SGS）。为了与正常场星系进行对比，我们还依据相互作用星系光谱样本（SGS）的红移分布，光度分布和聚集度参数分布，从SDSS DR7中随机挑选出了场星系样本，建立了对照星系样本（CGS）。通过对这两个样本（SGS和CGS）的比较，发现SGS与CGS在以下几个方面具有显著差异： 1）g-r颜色分布的差异。如果把星系的g-r颜色粗略分为三个层次，蓝、红及中间颜色，则与场星系样本（CGS）相比，相互作用星系样本（SGS）具有更高比例的蓝星系及红星系。具有更多蓝星系的原因通常归结为相互作用所触发的恒星形成所致。而对于SGS中存在更高比例的红星系的原因，人们没有统一的看法。通常认为，星系环境是造成这一现象的重要因素。因为相对场星系来说，相互作用星系一般处于高密度的星系环境中，根据环境与颜色的关系，这类星系颜色要偏红。然而，本文的SGS星系都是孤立的“星系对”，故环境应该不是造成这种差异的主要因素。通过本文的研究，我们认为SDSS对紧密“星系对”的低精度测光可能是原因之一。 2）星系中心（fiber）颜色及整体（Petrosian）颜色的差异。通过对SGS及CGS样本中星系的fiber颜色及Petrosian颜色进行分析，我们发现，相互作用星系的恒星形成具有向星系中心聚集的迹象，，这一结论与大部分相互作用星系的数值模拟结果一致。 3）光度（质量）-金属丰度关系的差异。研究表明，与场星系样本（CGS）相比，相互作用星系样本（SGS）在光度/质量－金属度关系曲线上存在明显的offset（偏低），我们认为这是由于相互作用引发气体向星系中心下落进而稀释星系中心的金属丰度引起。最后，我们还利用本文所建立相互作用星系样本，对Faber等在2007年提出的几种星系演化（从蓝云到红序）的途径mix quenching、early quenching及late quenching进行了分析，我们认为mix quenching可能是星系演化的正确途径。
[Abstract]:Intergalactic interactions and intergalactic interactions play an important role in the evolution of galaxies. Numerical simulations show that the interaction between galaxies and galaxies will cause strong disturbances in the stars and gases inside the galaxy, which is important for the galaxy's luminosity, color, morphology, metallicity, and internal star formation. In general, the interaction of "Galaxy pairs" has a stronger star formation than the field galaxy, the color is blue, and the shape is more irregular. A large number of statistical research results support similar views. However, due to the conditions of observation and the limitation of data, different research works in the selection and statistics of "galaxy pair" statistical samples. There are significant differences in the adoption of the law, so the statistical results obtained are often inconsistent.
Based on the work of Allam (2004), this paper recognizes a large, high-quality "galaxy pair" sample from the SDSS DR2 photometry database, which contains 8792 pairs of isolated interaction "Galaxy pairs". These "Galaxy pairs" have small projection spacing, and there are no other interfering galaxies around them. The effect on the properties of galaxies is very important. In addition, by collecting the various photometric data and spectral data of the sample galaxy, a more perfect Galaxy sample containing the photometric data and spectral data is further established, including 2779 interacting galaxies. This part of the galaxy is the main part of this paper to do statistical research. In order to compare with normal field galaxies, in order to compare with the normal field galaxies, we also choose the sample of the field galaxies randomly from the SDSS DR7 and set up a sample of the control galaxies (CGS), in order to compare with the normal field galaxies, in order to compare with the normal field galaxies, we also choose the distribution of the red shift, the luminosity distribution and the aggregation parameters of the interacted Galaxy spectrum sample (SGS), and the random sample of the field galaxies is selected from the SDSS DR7.
By comparing these two samples (SGS and CGS), it is found that there are significant differences between SGS and CGS in the following aspects:
1) differences in G-R color distribution. If the G-R color of galaxies is roughly divided into three levels, blue, red and intermediate colors, the interaction Galaxy sample (SGS) has a higher proportion of the LAN-STAR and red stars compared with the field Galaxy sample (CGS). The reasons for the more blue galaxies are usually attributed to the star formation triggered by interaction. There is no unified view of the reasons for the higher proportion of the red star system in SGS. It is generally believed that the galaxy environment is an important factor in this phenomenon. Because the relative galaxies are generally in the high density Galaxy environment, the color of these galaxies should be red according to the relationship between the environment and color. The SGS galaxies in this paper are isolated "Galaxy pairs", so the environment should not be the main factor in this difference. Through this study, we think that SDSS may be one of the reasons for the compact "galaxy pair" low precision photometry.
2) the difference in the color of the galaxy center (fiber) and the color of the whole (Petrosian). By analyzing the fiber color and the Petrosian color of the galaxies in the SGS and CGS samples, we find that the star formation of the interacting galaxies has a sign of aggregation to the center of the galaxy. This conclusion is in agreement with the numerical simulation results of most interacting galaxies.
3) differences in the relationship between photometric (mass) - metal abundance. The study shows that, compared with the field Galaxy sample (CGS), the interacted Galaxy sample (SGS) has an obvious offset (low) on the photometric / mass metallicity relation curve, which we think is due to the metal abundance of the interaction of gas from the center of the galaxy to the center of the galaxy and then diluting the center of the galaxy. Cause.
Finally, we also use the sample of interacting galaxies in this paper to analyze several kinds of galaxy evolution (from blue cloud to red order) proposed by Faber in 2007, such as mix quenching, early quenching and late quenching, and we think mix quenching may be the correct way of galaxy evolution.
【学位授予单位】：上海师范大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：P15

【共引文献】