发表机构
Massachusetts Institute of Technology; Columbia University; Michigan State University; University of Cambridge; University of Modena and Reggio Emilia; Universidad de Santiago de Chile（麻省理工学院; 哥伦比亚大学; 密歇根州立大学; 剑桥大学; 摩德纳和雷焦艾米利亚大学; 智利圣地亚哥大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文利用FUSE光谱测量29个大质量椭圆星系的O VI发射，推断CGM冷却速率，发现其高于文献值约80%，且冷却效率随质量演化，从10^5.5 K到分子相的冷却被抑制一个数量级。
AI 中文摘要
这是本系列论文中的第二篇，我们采用现代方法重新审视了来自远紫外光谱探测器（FUSE）的29个大质量椭圆星系的档案远紫外光谱。在第一篇论文中，我们利用孔径匹配测光进行了SED建模，并分析了这些星系中的年轻和年老恒星族。在本论文中，我们报告了每个星系经过消光校正的O VI λλ1032,1038 Å通量及上限，并利用这些数据在稳态辐射冷却假设下，通过星系周介质（CGM）的多相凝聚推断气体冷却通过10^5.5 K的速率（\\(\dot{M}_{\rm O\\,VI}\\)）。通过同时考虑银河系内和本征消光，我们发现\\(\dot{M}_{\rm O\\,VI}\\)普遍大于文献中先前报道的值，中位数增大约80%。此外，我们量化了\\(\dot{M}_{\rm O\\,VI}\\)与恒星形成率、基于经典光度的X射线冷却速率以及X射线光谱冷却速率之间的相关性。结果表明，来自\\(\gtrsim 10^7\\) K的星系周介质的冷却效率随宿主质量演化，在星系团尺度上比在星系群和椭圆星系尺度上被抑制约4-5倍。相反，在稳态冷却假设下，从10^5.5 K冷却到分子相的效率似乎被抑制了一个数量级，且与质量无关，这需要湍流混合层、热传导、多相循环、底重初始质量函数或其他额外物理机制来解释。
英文摘要
This is the second paper in a series where we examine archival far-ultraviolet spectroscopy of 29 massive elliptical galaxies from the Far Ultraviolet Spectroscopic Explorer (FUSE) with modern methods. In the first paper, we performed SED modeling with aperture-matched photometry and analyzed the young and old stellar populations in these galaxies. In this paper, we report extinction-corrected O VI $λλ$1032,1038 $\mathring{\rm A}$ fluxes and upper limits for each galaxy, which we use to infer the rate at which gas is cooling through $10^{5.5}$ K via multiphase condensation of the galaxy's CGM ($\dot{M}_{\rm O\,VI}$) under the assumption of steady radiative cooling. By considering both Galactic and intrinsic extinction, we overwhelmingly find $\dot{M}_{\rm O\,VI}$ to be larger than values found previously in the literature by a median of $\sim 80\%$. Additionally, we quantify correlations between $\dot{M}_{\rm O\,VI}$ and star formation rates, classical luminosity-based X-ray cooling rates, and X-ray spectroscopic cooling rates. The results suggest that the efficiency of cooling from the $\gtrsim 10^7$ K circumgalactic medium evolves with host mass, being suppressed by a factor of $\sim 4$-$5$ more at the cluster scale than it is at the group and elliptical scales. In contrast, under the steady cooling assumption, cooling from $10^{5.5}$ K to the molecular phase appears to be suppressed by an order of magnitude, independent of mass, requiring turbulent mixing layers, thermal conduction, multiphase recycling, a bottom-heavy initial mass function, or some other additional physics to explain.
CommentsSubmitted to ApJ. The data release on Zenodo will be made public following the review process
