【摘要】：星系團(tuán)是宇宙中最大的引力束縛系統(tǒng),其最亮的成員星系(也稱作最亮團(tuán)星系,英文Brightest Cluster Galaxy)是星系形成與演化重要的研究對(duì)象之一。最亮團(tuán)星系通常是寧靜的巨橢圓星系,它們大多由年老的恒星族所主導(dǎo),已沒有較強(qiáng)的恒星形成活動(dòng)。早期的研究表明:低紅移(z0.4)或近鄰最亮團(tuán)星系中僅有非常小的一部分比例(0.5%左右)具有恒星形成活動(dòng)。造成這些最亮團(tuán)星系中恒星形成活動(dòng)的冷氣體主要來源于星系團(tuán)中熱氣體的冷卻(cooling)。最近基于哈勃空間望遠(yuǎn)鏡(HST)多波段觀測(cè)CLASH巡天項(xiàng)目的研究發(fā)現(xiàn):在23個(gè)中等紅移(0.18z0.89)的星系團(tuán)中,有9個(gè)最亮團(tuán)星系具有較強(qiáng)的恒星形成活動(dòng)(約40%)。造成這些中等紅移最亮團(tuán)星系中恒星形成活動(dòng)的冷氣體的來源目前還不十分清楚。為了進(jìn)一步確定造成這些中等紅移最亮團(tuán)星系中恒星形成活動(dòng)的冷氣體來源,本文對(duì)CLASH巡天最亮團(tuán)星系的性質(zhì)做進(jìn)一步的研究。首先我們對(duì)其中23個(gè)CLASH星系團(tuán)的物理性質(zhì)(質(zhì)量、中心區(qū)域的熵等)與其最亮成員星系中的恒星形成活動(dòng)間的關(guān)系進(jìn)行了研究。其次基于多波段、高精度面源測(cè)光處理,我們進(jìn)一步研究了CLASH最亮團(tuán)星系在靜止坐標(biāo)系(Rest-frame)下的NUV-I顏色輪廓。通過NUV-I顏色輪廓分析,我們進(jìn)一步確認(rèn)是否這些中等紅移最亮團(tuán)星系中具有恒星形成活動(dòng)。本文的主要研究結(jié)果如下:(1)中等紅移最亮團(tuán)星系的總恒星形成率與其宿主星系團(tuán)的質(zhì)量、中心區(qū)域的熵值存在明顯的相關(guān):質(zhì)量越小、中心區(qū)域熵值越低的星系團(tuán)中其最亮成員星系的恒星形成率越高,而與最亮成員星系本身的物理性質(zhì)(如恒星質(zhì)量)幾乎不存在相關(guān)。(2)具有恒星形成活動(dòng)的最亮成員星系的NUV-I顏色梯度為正向的(具有藍(lán)色的核)。進(jìn)一步確認(rèn)25個(gè)CLASH最亮團(tuán)星系中有9個(gè)具有明顯恒星形成活動(dòng)(~36%)。本文的研究結(jié)果表明:CLASH星系團(tuán)最亮成員星系中確實(shí)有較高的比例(~36%)具有明顯恒星形成活動(dòng);造成中等紅移最亮成員星系中恒星形成活動(dòng)的冷氣體主要來源于其宿主星系團(tuán)內(nèi)的熱氣體冷卻,而不是星系本身。然而,既然這些冷氣體主要來源于星系團(tuán)中熱氣體的冷卻,那么星系團(tuán)中心區(qū)域其它大質(zhì)量成員星系中可能也會(huì)有相對(duì)較弱的恒星形成活動(dòng),在未來的研究工作中我們將對(duì)星系團(tuán)中心區(qū)域其它大質(zhì)量團(tuán)星系進(jìn)行研究,以進(jìn)一步確認(rèn)這些造成恒星形成活動(dòng)的冷氣體來源。
[Abstract]:Cluster of galaxies is the largest gravitational binding system in the universe, and its brightest member galaxies (also known as brightest cluster galaxies). Brightest Cluster Galaxy) is one of the most important research objects in the formation and evolution of galaxies. The brightest cluster galaxies are usually tranquil giant ellipsoid galaxies, mostly dominated by older constellations, without strong star-forming activity. Early studies have shown that only a very small proportion (about 0.5%) of low redshift (z 0.4) or nearest neighbor brightest cluster galaxies (about 0.5%) has star formation activity. The cold gas that causes star formation activity in these brightest cluster galaxies comes mainly from the cooling (cooling). Of the hot gas in the cluster of galaxies. A recent study based on the Hubble Space Telescope (HST) Multi-band observation CLASH Sky Survey found that of the 23 medium Red shift (0.18z0.89) clusters, 9 of the brightest cluster galaxies had strong star formation activity (about 40%). The source of the cold gas that causes star-forming activity in these medium-redshift brightest cluster galaxies is unclear. In order to further determine the source of cold gas causing star formation activity in these medium redshift brightest cluster galaxies, the properties of CLASH survey brightest cluster galaxies are further studied in this paper. First, we investigate the relationship between the physical properties (mass, entropy of the central region) of 23 CLASH clusters and star formation activities in their brightest member galaxies. Secondly, based on the multi-band, high-precision surface source photometric processing, we further study the NUV-I color contours of the brightest cluster galaxies in CLASH in the static coordinate system (Rest-frame). By NUV-I color profile analysis, we further confirm whether there is star formation activity in these medium redshift brightest cluster galaxies. The main results of this paper are as follows: (1) the total star formation rate of the medium redshift brightest cluster galaxy is significantly correlated with the mass of its host cluster, and the entropy of the central region: the smaller the mass, the higher the entropy of the central region. The lower the entropy in the central region, the higher the star formation rate of its brightest member galaxies. There is almost no correlation with the physical properties of the brightest member galaxies (such as star mass). (2) the NUV-I color gradient of the brightest member galaxies with star-forming activity is positive (with blue nuclei). It is further confirmed that 9 of the 25 CLASH brightest cluster galaxies have significant star formation activity (~ 36%). The results of this study show that the brightest member galaxies in the CLASH cluster do have a higher proportion (~ 36%) of star formation activities. The cold gas that causes star formation activity in the brightest member galaxies with medium redshift mainly comes from the cooling of hot gas in its host cluster, not from the galaxy itself. However, since these cold gases are mainly derived from the cooling of hot gases in the cluster, there may also be relatively weak star formation activity in other large mass member galaxies in the central region of the cluster. In future work, we will study other large mass cluster galaxies in the central region of the cluster to further identify the sources of these cold gases that cause star formation activity.
【學(xué)位授予單位】：沈陽師范大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2016
【分類號(hào)】：P152

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本文編號(hào)：2468255