本文選題：星系形成與演化 + 橢圓星系�。� 參考：《南京大學(xué)》2014年博士論文

【摘要】：大質(zhì)量早型星系的形成與演化是星系物理研究中一個獨特且近來備受關(guān)注的話題。越來越多的高紅移星系的觀測研究揭示出了這類星系在其演化過程中所經(jīng)歷的不同階段和顯著的結(jié)構(gòu)上的轉(zhuǎn)變。為了進(jìn)一步確認(rèn)大質(zhì)量早型星系的結(jié)構(gòu)演化圖像,進(jìn)一步完善其形成演化的模型,我們對近鄰和中等紅移處的早型星系的多波段測光結(jié)構(gòu)研究進(jìn)行了細(xì)致的二維圖像的成分分解研究。 首先,我利用來自卡內(nèi)基-歐文巡天所提供的94個明亮的近鄰橢圓星系的高質(zhì)量地面光學(xué)圖像對這個具有一定代表性的橢圓星系樣本進(jìn)行了細(xì)致的二維測光分解研究。樣本分布在恒星質(zhì)量M*=1010.2to1012.0M(?)的區(qū)間和一定的環(huán)境分布上。利用二維圖像分解技術(shù)所賦予的獨特能力,我討論了在近鄰橢圓星系中發(fā)現(xiàn)測光性質(zhì)上有顯著區(qū)別的子結(jié)構(gòu)的可能,以及是否能夠利用這些結(jié)構(gòu)對其形成歷史進(jìn)行更好的限制。相比于傳統(tǒng)的一維測光技術(shù),二維模型可以同時準(zhǔn)確的復(fù)原出橢圓星系的面亮度輪廓和其幾何形狀隨著半徑的系統(tǒng)變化。與之前基于一維面亮度輪廓得到的模型有很大不同,我的工作明確的指出大部分的近鄰橢圓星系(≥75%)的二維面亮度分布不能很好的用一個Sersic成分來進(jìn)行描述。與之對應(yīng)的,我發(fā)現(xiàn)這些橢圓星系的測光結(jié)構(gòu)都包含三個性質(zhì)上有區(qū)別的S∈rsic子成分：一個包含總光度10%-15%的較為致密的中心成分；一個占總光度20%-25%的,平均有效半徑Re≈2.5kpc的中間成分；以及一個占光度主導(dǎo)地位(f=0.6)的延展(Re≈10kpc)外側(cè)成分。各個成分的面亮度分布的Sersic指數(shù)均在n≈1—2之間,比之前工作中對整體面亮度輪廓擬合得到的要低得多。每個成分都各自很好的符合已知的橢圓星系的測光標(biāo)度關(guān)系以及重要的質(zhì)量-半徑關(guān)系,盡管相關(guān)的緊致程度以及關(guān)系的斜率略有不同。結(jié)合這些具體的性質(zhì)和標(biāo)度關(guān)系,我們對這些成分的物理性質(zhì)和可能的起源進(jìn)行了討論。 為了進(jìn)一步的將這些獨特的子結(jié)構(gòu)的性質(zhì)與大質(zhì)量星系在過去100億年的時標(biāo)上的結(jié)構(gòu)演化聯(lián)系起來,我嘗試將近鄰橢圓星系的測光子結(jié)構(gòu)與在較高紅移處觀測到的大質(zhì)量早型星系的測光性質(zhì)進(jìn)行比較。我發(fā)現(xiàn)將前面模型中包含的中心和中間兩個成分合并起來考慮的時候,這個符合的測光結(jié)構(gòu)遵守著一個異常緊致的質(zhì)量-有效半徑關(guān)系。并且,更加有趣的是,這個關(guān)系與在紅移≈1.0處觀測到的大質(zhì)量早型星系所遵守的質(zhì)量-有效半徑關(guān)系非常一致。通過比較這些星系的平均質(zhì)量密度輪廓,可以進(jìn)一步的發(fā)現(xiàn),在星系中心1.0kpc以外,近鄰早型的中心復(fù)合測光結(jié)構(gòu)與z≥1.5的大質(zhì)量早型星系非常接近。盡管當(dāng)考察具體星系時,也可以發(fā)現(xiàn)很多近鄰橢圓星系的中心復(fù)合結(jié)構(gòu)相比于高紅移的典型早型星系,也有了一定的半徑增長。基于這個觀測比較的結(jié)果,我提出,在近鄰橢圓星系中利用成分分解方法提取出的中心復(fù)合成分很可能和高紅移處的大質(zhì)量寧靜致密星系("Red-Nuggets")有著直接的演化聯(lián)系。而這個成分,很可能就是在最近提出的大質(zhì)量星系演化的兩階段模型中,通過第一個階段中的劇烈的耗散過程引發(fā)的恒星形成過程形成的。根據(jù)這個模型,在隨后的非耗散過程占主導(dǎo)的時期,通過一系列的并和,尤其是不涉及耗散過程的干并和過程逐漸累積形成了近鄰橢圓星系外部的延展恒星包層。從近鄰橢圓星系中分解出的外部測光結(jié)構(gòu)在質(zhì)量-有效半徑關(guān)系上的顯著的彌散很可能正反應(yīng)了這個并和主導(dǎo)階段的隨機特性。 雖然兩階段形成模型逐漸獲得了越來越多的觀測支持,包括我們從近鄰橢圓星系的測光結(jié)構(gòu)中得到的證據(jù)的支持,但距離真正的確立其可靠的地位還有一段距離。在兩階段形成模型中,一個非常重要的參量就是在第二個由干并和主導(dǎo)的階段中,不同質(zhì)量比的并和各自發(fā)生了多少次；換句話說,即平均的干并和質(zhì)量比是多少。在模型中,這個參量很大程度上決定了早型星系的半徑成長和面亮度輪廓的變化。然而,這個重要參數(shù)的觀測限制卻是非常難獲得的。為此,我構(gòu)想了一個基于多成分橢圓星系測光模型結(jié)果的手段,結(jié)合一些基本假設(shè),對這個參數(shù)嘗試給出觀測限制。首先,利用非常簡單可靠的參數(shù)限制,我成功的將在V-band上獲得的多成分模型拓展到S-band和R-band上去。利用這組多波段模型,我將近鄰橢圓星系測光分解出的中心復(fù)合成分與外部延展成分之間的光學(xué)顏色差別與組成它們的主要星族平均性質(zhì)聯(lián)系起來。考慮到早型星系遵守著一個有良好定義的質(zhì)量-顏色關(guān)系,并且如果假定在兩階段形成模型的背景下,大質(zhì)量橢圓星系在其中的恒星形成階段后就只通過多次干并和沿著質(zhì)量-顏色關(guān)系向大質(zhì)量端演化,那么我們得到的顏色差異恰好可以幫助我們對于平均并和質(zhì)量比給出一個粗略的限制。盡管目前這個方法還受到很多數(shù)據(jù)不確定性上的限制,但我得到的結(jié)果：5—15：1的平均并和質(zhì)量比與目前的數(shù)值模擬給出的范圍符合的較好。 隨后,為了更加直觀的給出一個大質(zhì)量星系結(jié)構(gòu)演化的基本圖像,我認(rèn)為最直接的觀測方法就是利用HST對高紅移早型星系的觀測數(shù)據(jù)和一致的二維測光分解技術(shù)對進(jìn)行細(xì)致的結(jié)構(gòu)分析。如果兩階段模型的正確性能得到未來觀測的證實,那么我們可以很自然的想到,隨著高質(zhì)量的高紅移早型星系觀測的出現(xiàn),我們必定可以看到橢圓星系中心成分經(jīng)歷的結(jié)構(gòu)變化以及外部延展恒星包層的逐漸累積。盡管難度相比于近鄰橢圓星系要增加了很多,我通過使用非常獨特的哈勃極深場觀測覆蓋的7個分布在z=0.6—1.5之間的早型星系的靜止波長下的近紅外極深曝光數(shù)據(jù)與CANDELS巡天提供的相同星系在相同波段上的正常曝光深度的圖像的對比給出了非常令人振奮的結(jié)果。我的測光分解分析指出：(1)這些中等紅移處的早型星系絕大多數(shù)已經(jīng)有明顯的多成分結(jié)構(gòu)的證據(jù)；(2)雖然目前HST觀測在分辨率和觀測深度上還不足以提供這些高紅移星系和近鄰橢圓星系可以比較的圖像,像CANDELS這樣的巡天項目已經(jīng)足以用來對z≤1.5的大質(zhì)量早型星系進(jìn)行結(jié)構(gòu)分解研究。盡管這還僅僅是對一個不完備小樣本的試探性結(jié)果,也已經(jīng)為我們進(jìn)一步開展后面針對高紅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.
【學(xué)位授予單位】：南京大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2014
【分類號】：P152

【共引文獻(xiàn)】

相關(guān)博士學(xué)位論文 前1條

1 林琳;近鄰星系中恒星形成區(qū)及星族特性二維分布的研究[D];中國科學(xué)技術(shù)大學(xué);2013年

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本文編號：1902424