星系中分子气体与恒星形成的研究进展

Progress on the Study of Molecular Gas and Star Formation in Galaxies

星系中气体转化为恒星的过程决定了星系的结构和演化,因此研究恒星形成最直接的原料--分子气体的含量、分子气体形成恒星的规律以及会受哪些物理机制的影响,对于理解星系的形成和演化具有重要意义。近年来,随着观测技术和设备(尤其是射电望远镜)的发展,天文学家可以在不同尺度上探测到越来越多星系的多种分子多种能级跃迁的谱线。首先,介绍了探测分子气体的多种方法和新的发现;然后基于CO巡天数据和致密分子气体数据,分别在统计上讨论了分子气体分布及分子气体含量与恒星形成率之间的紧密关系,并与小尺度上的恒星形成理论进行了比较;最后,结合影响星系演化的物理过程,讨论活动星系核、星系形态以及星系所处环境对分子气体的影响。

Star formation is a process that gas cool,condense and form stars,and it plays a very important role in galaxy structure growth and evolution.Therefore it is important to study the molecular gas content,its relationship to star formation,and the physical processes that affect properties of galaxies,to have a complete picture of galaxy formation and evolution.With the advancement of observational technology(especially radio telescope),recently,there are more and more studies of molecular gas at various scales.This review gives a summary on recent progress:first we introduce various methods of tracing molecular gas and the new results;then review the molecular gas scaling relations from statistical studies,including molecular gas fraction and depletion time,based on observations of CO emission lines and dense gas tracers,and then compare them with theory of star formation on small scales;finally discuss how the morphology quenching,AGN feedback,and environment affect the molecular gas in galaxies and cease the star formation.