近邻椭圆星系的测光结构与演化历史

发布时间：2018-05-17 18:37

本文选题：星系形成与演化 + 椭圆星系　；参考：《南京大学》2014年博士论文

【摘要】：大质量早型星系的形成与演化是星系物理研究中一个独特且近来备受关注的话题。越来越多的高红移星系的观测研究揭示出了这类星系在其演化过程中所经历的不同阶段和显著的结构上的转变。为了进一步确认大质量早型星系的结构演化图像,进一步完善其形成演化的模型,我们对近邻和中等红移处的早型星系的多波段测光结构研究进行了细致的二维图像的成分分解研究。首先,我利用来自卡内基-欧文巡天所提供的94个明亮的近邻椭圆星系的高质量地面光学图像对这个具有一定代表性的椭圆星系样本进行了细致的二维测光分解研究。样本分布在恒星质量M*=1010.2to1012.0M(?)的区间和一定的环境分布上。利用二维图像分解技术所赋予的独特能力,我讨论了在近邻椭圆星系中发现测光性质上有显著区别的子结构的可能,以及是否能够利用这些结构对其形成历史进行更好的限制。相比于传统的一维测光技术,二维模型可以同时准确的复原出椭圆星系的面亮度轮廓和其几何形状随着半径的系统变化。与之前基于一维面亮度轮廓得到的模型有很大不同,我的工作明确的指出大部分的近邻椭圆星系(≥75%)的二维面亮度分布不能很好的用一个Sersic成分来进行描述。与之对应的,我发现这些椭圆星系的测光结构都包含三个性质上有区别的S∈rsic子成分：一个包含总光度10%-15%的较为致密的中心成分；一个占总光度20%-25%的,平均有效半径Re≈2.5kpc的中间成分；以及一个占光度主导地位(f=0.6)的延展(Re≈10kpc)外侧成分。各个成分的面亮度分布的Sersic指数均在n≈1—2之间,比之前工作中对整体面亮度轮廓拟合得到的要低得多。每个成分都各自很好的符合已知的椭圆星系的测光标度关系以及重要的质量-半径关系,尽管相关的紧致程度以及关系的斜率略有不同。结合这些具体的性质和标度关系,我们对这些成分的物理性质和可能的起源进行了讨论。为了进一步的将这些独特的子结构的性质与大质量星系在过去100亿年的时标上的结构演化联系起来,我尝试将近邻椭圆星系的测光子结构与在较高红移处观测到的大质量早型星系的测光性质进行比较。我发现将前面模型中包含的中心和中间两个成分合并起来考虑的时候,这个符合的测光结构遵守着一个异常紧致的质量-有效半径关系。并且,更加有趣的是,这个关系与在红移≈1.0处观测到的大质量早型星系所遵守的质量-有效半径关系非常一致。通过比较这些星系的平均质量密度轮廓,可以进一步的发现,在星系中心1.0kpc以外,近邻早型的中心复合测光结构与z≥1.5的大质量早型星系非常接近。尽管当考察具体星系时,也可以发现很多近邻椭圆星系的中心复合结构相比于高红移的典型早型星系,也有了一定的半径增长。基于这个观测比较的结果,我提出,在近邻椭圆星系中利用成分分解方法提取出的中心复合成分很可能和高红移处的大质量宁静致密星系("Red-Nuggets")有着直接的演化联系。而这个成分,很可能就是在最近提出的大质量星系演化的两阶段模型中,通过第一个阶段中的剧烈的耗散过程引发的恒星形成过程形成的。根据这个模型,在随后的非耗散过程占主导的时期,通过一系列的并和,尤其是不涉及耗散过程的干并和过程逐渐累积形成了近邻椭圆星系外部的延展恒星包层。从近邻椭圆星系中分解出的外部测光结构在质量-有效半径关系上的显著的弥散很可能正反应了这个并和主导阶段的随机特性。虽然两阶段形成模型逐渐获得了越来越多的观测支持,包括我们从近邻椭圆星系的测光结构中得到的证据的支持,但距离真正的确立其可靠的地位还有一段距离。在两阶段形成模型中,一个非常重要的参量就是在第二个由干并和主导的阶段中,不同质量比的并和各自发生了多少次；换句话说,即平均的干并和质量比是多少。在模型中,这个参量很大程度上决定了早型星系的半径成长和面亮度轮廓的变化。然而,这个重要参数的观测限制却是非常难获得的。为此,我构想了一个基于多成分椭圆星系测光模型结果的手段,结合一些基本假设,对这个参数尝试给出观测限制。首先,利用非常简单可靠的参数限制,我成功的将在V-band上获得的多成分模型拓展到S-band和R-band上去。利用这组多波段模型,我将近邻椭圆星系测光分解出的中心复合成分与外部延展成分之间的光学颜色差别与组成它们的主要星族平均性质联系起来。考虑到早型星系遵守着一个有良好定义的质量-颜色关系,并且如果假定在两阶段形成模型的背景下,大质量椭圆星系在其中的恒星形成阶段后就只通过多次干并和沿着质量-颜色关系向大质量端演化,那么我们得到的颜色差异恰好可以帮助我们对于平均并和质量比给出一个粗略的限制。尽管目前这个方法还受到很多数据不确定性上的限制,但我得到的结果：5—15：1的平均并和质量比与目前的数值模拟给出的范围符合的较好。随后,为了更加直观的给出一个大质量星系结构演化的基本图像,我认为最直接的观测方法就是利用HST对高红移早型星系的观测数据和一致的二维测光分解技术对进行细致的结构分析。如果两阶段模型的正确性能得到未来观测的证实,那么我们可以很自然的想到,随着高质量的高红移早型星系观测的出现,我们必定可以看到椭圆星系中心成分经历的结构变化以及外部延展恒星包层的逐渐累积。尽管难度相比于近邻椭圆星系要增加了很多,我通过使用非常独特的哈勃极深场观测覆盖的7个分布在z=0.6—1.5之间的早型星系的静止波长下的近红外极深曝光数据与CANDELS巡天提供的相同星系在相同波段上的正常曝光深度的图像的对比给出了非常令人振奋的结果。我的测光分解分析指出：(1)这些中等红移处的早型星系绝大多数已经有明显的多成分结构的证据；(2)虽然目前HST观测在分辨率和观测深度上还不足以提供这些高红移星系和近邻椭圆星系可以比较的图像,像CANDELS这样的巡天项目已经足以用来对z≤1.5的大质量早型星系进行结构分解研究。尽管这还仅仅是对一个不完备小样本的试探性结果,也已经为我们进一步开展后面针对高红移星系的工作提供了信心。
[Abstract]:The formation and evolution of large mass early galaxies is a unique and recent topic of concern in the study of Galaxy physics. More and more observational studies of high redshift galaxies reveal the different stages and significant structural changes in the evolution of these galaxies. In order to further improve the evolution of the model, we have studied the multi-band optical structure of the early type galaxies in the near and medium red shifts to study the component decomposition of the two-dimensional images.
First, I use the high quality ground optical images of 94 bright adjacent elliptical galaxies from the Carnegie Erwin cruise to study the detailed two-dimensional photometric decomposition of this representative elliptical galaxy sample. The samples are distributed in the interval of the star mass M*= 1010.2to1012.0M (?) and a certain environmental distribution. Using the unique ability given by the two-dimensional image decomposition technique, I discuss the possibility of finding the distinct substructures in the adjacent elliptical galaxies, and whether they can make use of these structures to better limit their history. The surface luminance profile and its geometric shape change with the radius of the elliptical galaxy. It is very different from the previous model based on one dimension luminance contour. My work clearly points out that most of the nearest neighbor elliptical galaxies (> 75%) can not be well described by a Sersic component. Yes, I find that the photometric structures of these elliptical galaxies contain three distinct S RSIC subcomponents: a denser central component that contains the total photometric 10%-15%; an intermediate component of the total photometric 20%-25%, the mean effective radius Re 2.5kpc; and a Re 10%-15% extension (Re 10). KPC) lateral components. The Sersic index of each component's surface brightness distribution is between N 1 and 2, which is much lower than that obtained in the previous work on the overall surface luminance contour. Each component fits well with the measured scale relation of the known elliptical galaxies and the important mass radius relation, despite the relative tighten degree. The slope of relationship is slightly different. Combined with these specific properties and scaling relations, we discuss the physical properties and possible origins of these components.
In order to further link the properties of these unique substructures with the structural evolution of large mass galaxies over the past 10 billion years, I have tried to compare the photometric properties of the near neighbor elliptical galaxies with the large mass early type galaxies observed at higher red shifts. When the two components of the center and the center are combined to consider, this conformed optical structure observes an abnormally compact mass effective radius relationship. And, more interestingly, the relationship is very consistent with the mass - effective radius observed by the large mass early galaxies observed at the red shift 1. The average mass density profile of the system can be further found that near the center 1.0kpc of the galaxy, the central composite photometric structure of the near neighbour early type is very close to the large mass early type galaxies with Z > 1.5. Although when the specific galaxies are examined, many central complex structures of adjacent elliptical galaxies can be found to be compared to the typical early type stars with high redshift. Based on the results of this observation, I suggest that the central compound extracted by the component decomposition method in the adjacent elliptical galaxies is likely to have a direct evolutionary link with the high mass tranquil and quiet compact galaxies ("Red-Nuggets"), which is likely to be recently proposed. The two stage model of the evolution of large mass galaxies, formed by the process of stellar formation caused by the violent dissipative process in the first stage. According to this model, the subsequent non dissipative process dominated by a series of and gradually accumulated a close neighbor, especially the dry and process that does not involve the dissipative process. The ductile stellar cladding outside the elliptical galaxy. The apparent dispersion of the external photometric structure from adjacent elliptical galaxies in the mass effective radius relationship is likely to reflect this and the randomness of the dominant phase.
Although the two stage formation model has gradually gained more and more observation support, including our evidence from the optical structure of the adjacent elliptical galaxies, it is still a certain distance from the real establishment of its reliable position. In the two phase of the model, a very important parameter is in the second by the dry and dominant. In the phase, how many times have different mass ratios have occurred and each other; in other words, the average dry and mass ratio is much. In the model, this parameter largely determines the radius growth of the early type galaxies and the change of the surface luminance contour. However, the observation limit of this important parameter is very difficult to obtain. A method based on the results of a multi-component elliptical galaxy measurement model is proposed, and some basic assumptions are used to give an observation restriction to this parameter. First, using a very simple and reliable parameter limit, I successfully extended the multicomponent model on V-band to S-band and R-band. The optical color differences between the central composite components and the external ductile components of the adjacent elliptical galaxies are associated with the main star family, considering that early galaxies are complying with a well defined mass color relationship, and if it is assumed in the background of the two stage to form a model, large mass ellipses are assumed. After the star formation stage in the galaxy, it only evolves by multiple dry and mass color relations to the mass end, then the color difference we get can help us to give a rough limit to the average and mass ratio, although this method is still limited by a lot of data uncertainty, however. I get the result: the average and mass ratio of 5 - 15:1 is in good agreement with the range given by the present numerical simulation.
Then, in order to give a more intuitive picture of the evolution of large mass Galaxy structure, I think the most direct method of observation is to use HST to analyze the structure of high redshift early galaxies and the uniform two-dimensional photometric decomposition technique. If the correct performance of the two stage model gets the proof of the future observation. In fact, we can naturally think that with the appearance of high quality high redshift early Galaxy observations, we can see the structural changes in the central component of the elliptical galaxy and the gradual accumulation of the outer ductile stellar cladding. Although the difficulty is much more than the nearest neighbor ellipsoid, I use very unique use. A very exciting result of the contrast of the near infrared near infrared (near infrared) deep exposure data of 7 early galaxies distributed between z=0.6 and 1.5 at the stationary wavelength of the early type galaxies between z=0.6 and 1.5 and the same galaxy provided by the CANDELS cruise is very exciting. My photometric analysis points out: (1) these Most of the early type galaxies at the red shift have evidently multicomponent evidence; (2) although the current HST observations are not enough to provide a comparable image of these high red shift galaxies and adjacent elliptical galaxies, the survey items such as CANDELS have been sufficient to be used for the mass early type of Z < 1.5. The study of the structural decomposition of galaxies, although this is only a tentative result of an incomplete small sample, has also provided us with confidence in the further work behind the work of high redshift galaxies.
【学位授予单位】：南京大学
【学位级别】：博士
【学位授予年份】：2014
【分类号】：P152

【共引文献】