星系环境和星系质量对星系演化的影响

发布时间：2018-03-25 17:26

本文选题：星系团　切入点：环境　出处：《中国科学技术大学》2013年博士论文

【摘要】：星系团是宇宙中物质分布最致密的区域,是星系演化的天然实验室。在星系团中,从中心区域到外围,团成员物理性质,如形态、恒星形成率、星族年龄等,呈现出不同程度的差异。星系环境的研究则是从星系分布最致密的区域到最稀疏的区域,分析环境效应对星系物理性质及其演化路径的影响,而不仅仅局限于星系团等区域。SDSS巡天提供了大样本的近邻星系样本,也提供了上百万个星系的红移,从而能够对星系环境进行比较准确的估计。最近,基于SDSS的样本,有关环境效应如何影响星系演化的这一类研究已经取得一系列成果,并且依然是很热门的课题。在本论文中,我们利用SDSS的数据和Beijing-Arizona-Taiwan-Connecticut (BATC)的多波段观测数据,对近邻星系团Abell671(A671)的子结构、光度函数、团成员恒星形成历史等性质进行研究。另外,我们还用COSMOS场的数据研究了介于宁静星系和恒星形成星系之间的绿谷(Green Valley)星系的物理性质和环境,试图探讨从红移z～1到现在,环境效应在这类星系的形成过程中所起的作用。本文第二章,我们利用SDSS的测光和光谱数据,以及BATC15个中带滤光片的多波段观测数据,对星系团A671进行了测光和光谱研究。通过将BATC的数据和SDSS的数据进行匹配,我们在A671581x58'的视场中匹配到了985个V波段亮于20.0mag的星系,其中包括103个由光谱红移确定的团成员星系。为了选取更多的暗成员星系,我们对BATC观测的数据进行能谱拟合,估计星系的测光红移。利用测光红移,结合颜色—星等图,我们新选取到了97个亮于BATC hBATC=19.5mag的新团成员。基于这个扩大了的样本,我们研究了A671的子结构。我们发现,仅用103个亮成员星系来测量时,子结构非常明显。但是在引入暗成员之后,子结构被平滑掉了。我们认为暗成员的测光红移值在指示子结构时不是太准确。A671在SDSS r波段的光度函数可以很好的用Schechter函数来拟合,暗端斜率比较平,α=-1.12。我们用STARLIGHT来拟合SDSS的光谱,研究了亮成员的恒星形成历史。我们发现,处在星系团核心区域的早型星系要比外围的年老。而金属丰度则没有表现出环境效应。无论是早型星系还是晚型星系,它们的星族年龄和金属丰度都和恒星质量强烈相关。我们的发现支持"downsizing"的星系演化模式。通过将早型星系的Lick指数和简单星族的模型进行比较,我们得到了早型星系的年龄、[Fe/H].[Mg/Fe]、[C/Fe]、[N/Fe]等参数。我们发现,星系团核心区域的早型星系的星族年龄指针Hβ等值宽度要比外围的小,这说明中心星系较为年老。而指示总金属丰度的[MgFe]'指数,则没有表现出环境效应。得到的[Fe/H].[Mg/Fe]等参数与星系速度弥散值相关,这与以前的研究结果符合。论文第三章,我们在COSMOS场中选取了一个数目约为2350个,处于z=[0.2,1.0]的”Green Valley"星系样本(以下称为绿星系),研究了他们的形态、光谱和环境。我们用经过尘埃改正过的NUV-r+颜色来定义green valley,这有助于我们从绿谷地带中剔除掉富尘埃的恒星形成星系,从而选取到真实的过渡类型星系。绿星系在Gini-Asymmetry和Gini-M20的参数空间上都处在红、蓝星系之间。利用ZEST形态分类表,我们发现大概有60%--70%的绿盘星系有大的或者中等的核球成分,只有5%-10%绿星系是纯盘系统。绿星系的叠加谱有中等强度的[OⅡ], Ha和Hβ发射线。星族分析的结果显示,绿星系比红星系年轻,但是比蓝星系年老。我们用∑10研究了绿星系的环境。我们发现,在z0.7时,绿星系和蓝星系处在相似的环境中。但是在z0.7,大量的M*1010.0M⊙的绿星系出现在了高密度区域,这显著的不同于蓝星系。绿星系的形态和光谱特征符合过渡类型星系的性质。我们讨论了抑制恒星形成活动(quenching)的机制。在本文中,我们无法估计AGN反馈对quenching的影响。最后,我们认为环境效应,最有可能的是Starvation和Harassment,会在z0.5之后对M*1010.0M⊙的蓝星系起重要影响,从而使它们转变为红星系。研究结果支持,从z≈1到z=0,大质量星系中mass quenching始终占主导地位；而对于小质量星系,在z0.5时,environment quenching占主导。
[Abstract]:Regional material distribution of galaxies is the most dense in the universe, is a natural laboratory. The evolution of galaxies in the cluster, from the central area to the periphery, members of physical properties, such as morphology, star formation rate, population age, showing different degrees of difference. The research environment is from the Galaxy Galaxy distribution a dense region to the sparse region, analysis of the impact of environmental effect on the physical properties of galaxies and its evolution path, and not just in the cluster region.SDSS survey provides a large sample of neighboring galaxy samples also provide millions of Galaxy redshift, so as to be able to accurately estimate the Galactic environment. SDSS, based on how the environmental effect of this kind of research on the evolution of galaxies has made a series of achievements, and still is a very hot topic. In this paper, we use SDSS data and Beijing-Arizona-Taiwan-Connecticut (BATC) of the multi band observation data, Abell671 on neighboring galaxies (A671) subsystem, the luminosity function, members of the star formation history of nature. In addition, we also use the COSMOS field data of peace between galaxies and star forming galaxies between the Green Valley (Green Valley) the physical properties and the environment the galaxy, attempts to explore from redshift z ~ 1 to now, the environmental effect on the formation process of the galaxy's role.
In the second chapter, we use the photometric and spectroscopic data of SDSS, BATC15 and a multi band bandpass filter observations of galaxy clusters by A671 photometry and spectroscopy. By matching the BATC data and SDSS data, we in the A671581x58'field in the match to the 985 V band in 20.0mag light the galaxy, which includes 103 members is determined by the spectral redshift galaxies. In order to select more dark galaxies, we observed data of BATC spectra fitting, photometric redshift estimation of galaxies. Using photometric redshifts, combining the color magnitude diagram, we selected the new 97 BATC hBATC=19.5mag in new light the members of the delegation. Based on expanded sample, we studied the structure of A671. We found that only 103 bright galaxies to measure, the sub structure is very obvious. But after the introduction of dark members, sub structure Is smoothed out. We think the value of the member in the dark photometric redshift indicating the sub structure is not too accurate.A671 in the SDSS r band luminosity function can be very good with the Schechter function to fit the faint end slope, relatively flat, spectral fitting SDSS alpha =-1.12. we use STARLIGHT to study, members of the bright star formation history we found that in early type galaxies cluster core region than the periphery of old age. And the metal abundance showed no environmental effect. Whether early type galaxies or late type galaxies, their stellar age and metallicity are strongly associated with star quality. Our findings support the "downsizing" of the galaxy evolution model by the early type galaxies Lick index and simple population model comparison, we get the early type galaxies age, [Fe/H].[Mg/Fe], [C/Fe], [N/Fe] and other parameters. We found that the cluster core area New age pointer H beta equivalent width of early type galaxies than peripheral small, indicating that the center of the galaxy. While the older, indicating the total metallicity [MgFe]'index showed no effect. The environment parameters such as [Fe/H].[Mg/Fe] and Galaxy velocity dispersion values obtained, the results consistent with previous studies.
In the third chapter, we in the COSMOS field in the selection of a number of about 2350, in the "z=[0.2,1.0] Green Valley" (hereinafter referred to as green galaxies, galaxies) they were studied, and the environment. We use the spectrum by dust corrected NUV-r+ color to define Green Valley, which helps we removed from the Green Valley area of the dust rich star forming galaxies, so as to select the type of transition. The real green Galaxy Galaxy in the parameter space of Gini-Asymmetry and Gini-M20 are in red, LAN-STAR. Using ZEST morphology classification, we found that the green disc galaxies about 60%--70% of large or medium nuclear the ball, only 5%-10% is pure green Galaxy disk system. The spectra of galaxies superimposed green medium strength [O II], Ha and H beta emission lines. Population analysis shows that green galaxies younger than red galaxies, but than LAN-STAR. I am old We use 10 sigma of green Galaxy environment. We found that in the z0.7, and LAN-STAR in the green Galaxy in a similar environment. But in z0.7, a large number of M*1010.0M, the green galaxy appears in the high density region, which significantly different from LAN-STAR. The morphological and spectral characteristics of green Galaxy properties with the transition type galaxies. We discuss the suppression of star formation activity (quenching) mechanism. In this paper, we cannot estimate the effect of feedback on AGN quenching. Finally, we believe that the environmental effect, the most likely is Starvation and Harassment, in the z0.5 of M*1010.0M after the LAN-STAR system has an important effect, thus make them into red galaxies. The results support from z = 1 to z=0, mass quenching always dominant position of massive galaxies; and for low mass galaxies, in z0.5, environment and quenching are dominant.

【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：P157.9

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