论文标题
紫外线明亮的红色序列星系：紫外线上流和紫外线弱系统之间的比较研究
UV bright red-sequence galaxies: a comparative study between UV upturn and UV weak systems
论文作者
论文摘要
无论是否来自恒星，星系中的紫外线（UV）发射都与热成分相关。通过利用颜色彩色图，可以根据其紫外线排放的紫外线排放分为三类：残留的恒星形成，紫外线弱和紫外线的升高。该论文旨在通过将紫外线与紫外线弱系统进行比较来调查带有紫外线增长的星系。这项研究具有三个方面：（i）评估紫外线亮度ETG的紫外线上流系统的红移（z）和恒星质量（logm*）的进化； （ii）根据排放线对第一项研究的分层； （iii）在其出色的种群方面，被动RSG的紫外线弱和上升之间的比较。为了应对第一个前线，应用了贝叶斯逻辑模型。第二个正面在第一个方面扩展，将样本分为排放线类。最终的锋利的重点是利用来自GAMA-DR3的目录来研究紫外线弱和上流系统的恒星种群性能。结果表明，紫外线上流系统的比例上升到Z〜0.25，随后下降尚待证实。通过将样品分为发射线类，将星系分类为退休/被动（与进化的恒星相关的星系）用z和logm*主导行为。通过分析两种系统的恒星种群，自上次恒星形成以来，出现了不同的特征，例如中位年龄，金属性和时间。这些结果似乎表明，紫外线上流系统具有较窄的星形形成历史，金属性较高和较老的人群。
Ultraviolet (UV) emission from galaxies is associated with hot components, whether from stellar sources or not. By making use of colour-colour diagrams, early-type galaxies (ETGs) can be classified in terms of their UV emission in mainly three categories: residual star-formation, UV weak, and UV upturn. This thesis aims at investigating galaxies presenting UV upturn by comparing them to UV weak systems. This investigation has three fronts: (i) the assessment of the evolution in redshift (z) and stellar mass (logM*) of the fraction of UV upturn systems in terms of the total of UV bright ETGs; (ii) the stratification of the first study in terms of emission lines; (iii) the comparison between UV weak and upturn for passive RSGs in terms of their stellar populations. To tackle the first front, a Bayesian logistic model was applied. The second front expands on the first, dividing the sample into emission line classes. The final front is focused on the study of stellar population properties of UV weak and upturn systems, by making use of catalogues from GAMA-DR3. The results show that the fraction of UV upturn systems rises up to z~0.25, followed by a decline which remains to be confirmed. By stratifying the sample into emission line classes, the galaxies classified as retired/passive -- the ones associated with evolved stellar phases -- dominate the behaviour with z and logM*. By analysing the stellar populations of both types of systems, different characteristics emerge such as median ages, metallicities, and time since last burst of star formation. These results seem to indicate that UV upturn systems have narrower star-formation histories, higher metallicities, and slightly older populations.
