氦的沉积作用与布里渊星系团中的UV上升
Helium Sedimentation and the UV Upturn in Brightest Cluster Galaxies
摘要：
银河演化探测器（GALEX）的最新观测显示，在最亮的星系团（BCGs）光谱中存在强烈的意外紫外线过剩。我们认为，过量的紫外信号是由年老和演化的核心氦燃烧星产生的，如果祖星具有高的氦丰度值，紫外通量强度将大大增强。在这项工作中，我们提出，沉积过程可以大大提高在BCGs的He丰度。我们的模型预测，在更大规模的，低红移，和动态放松的BCGs的紫外线通量强度更强。这些预测可以用当前一代的GALEX+SDSS观测进行检验。
英文摘要：
Recent observations with Galaxy Evolution Explorer (GALEX) show strong unexpected UV excess in the spectrum of brightest cluster galaxies (BCGs). It is believed that the excess UV signal is produced by old and evolved core-He burning stars, and the UV flux strength could be greatly enhanced if the progenitor stars have high value of He abundance. In this work, we propose that sedimentation process can greatly enhance the He abundance in BCGs. Our model predicts that the UV flux strength is stronger in more massive, low-redshift, and dynamically relaxed BCGs. These predictions are testable with the current generation of GALEX+SDSS observations.
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