CLASH星系团最亮成员星系中恒星形成活动研究
发布时间：2019-04-29 12:45
【摘要】：星系团是宇宙中最大的引力束缚系统,其最亮的成员星系(也称作最亮团星系,英文Brightest Cluster Galaxy)是星系形成与演化重要的研究对象之一。最亮团星系通常是宁静的巨椭圆星系,它们大多由年老的恒星族所主导,已没有较强的恒星形成活动。早期的研究表明:低红移(z0.4)或近邻最亮团星系中仅有非常小的一部分比例(0.5%左右)具有恒星形成活动。造成这些最亮团星系中恒星形成活动的冷气体主要来源于星系团中热气体的冷却(cooling)。最近基于哈勃空间望远镜(HST)多波段观测CLASH巡天项目的研究发现:在23个中等红移(0.18z0.89)的星系团中,有9个最亮团星系具有较强的恒星形成活动(约40%)。造成这些中等红移最亮团星系中恒星形成活动的冷气体的来源目前还不十分清楚。为了进一步确定造成这些中等红移最亮团星系中恒星形成活动的冷气体来源,本文对CLASH巡天最亮团星系的性质做进一步的研究。首先我们对其中23个CLASH星系团的物理性质(质量、中心区域的熵等)与其最亮成员星系中的恒星形成活动间的关系进行了研究。其次基于多波段、高精度面源测光处理,我们进一步研究了CLASH最亮团星系在静止坐标系(Rest-frame)下的NUV-I颜色轮廓。通过NUV-I颜色轮廓分析,我们进一步确认是否这些中等红移最亮团星系中具有恒星形成活动。本文的主要研究结果如下:(1)中等红移最亮团星系的总恒星形成率与其宿主星系团的质量、中心区域的熵值存在明显的相关:质量越小、中心区域熵值越低的星系团中其最亮成员星系的恒星形成率越高,而与最亮成员星系本身的物理性质(如恒星质量)几乎不存在相关。(2)具有恒星形成活动的最亮成员星系的NUV-I颜色梯度为正向的(具有蓝色的核)。进一步确认25个CLASH最亮团星系中有9个具有明显恒星形成活动(~36%)。本文的研究结果表明:CLASH星系团最亮成员星系中确实有较高的比例(~36%)具有明显恒星形成活动;造成中等红移最亮成员星系中恒星形成活动的冷气体主要来源于其宿主星系团内的热气体冷却,而不是星系本身。然而,既然这些冷气体主要来源于星系团中热气体的冷却,那么星系团中心区域其它大质量成员星系中可能也会有相对较弱的恒星形成活动,在未来的研究工作中我们将对星系团中心区域其它大质量团星系进行研究,以进一步确认这些造成恒星形成活动的冷气体来源。
[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.
【学位授予单位】：沈阳师范大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P152
本文编号：2468255
[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.
【学位授予单位】：沈阳师范大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：P152
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