报告题目：Cold, Warm and Hot Molecular Gas in Infrared Galaxies

　　报 告 人：Nanyao Lu (Caltech)

　　摘    要：We present our results from Herschel/SPIRE spectroscopic observations of CO J-to-(J-1) transitions for a large sample of luminous IR galaxies. We show that molecular gas in IR galaxies generally consists of up to 3 distinctive temperature/density components. While CO (1-0) probes the cold phase, the mid-J (4 < J < 10) CO line emission arises from a warm gas phase dominated by current star formation (SF). An AGN can result in a hot gas that emits primarily at J > 10. This picture is further supported by our on-going high angular resolution (<0.2" or 100 pc) ALMA mapping in CO (6-5) that unveiled a good spatial correlation between the warm CO line emission and other SF tracers. Our data suggest that a mid-J CO line emission, e.g., CO (7-6), is a good SF rate tracer, which may be less AGN-contaminated and more practical in the upcoming ALMA era than the total IR dust emission at cosmological distances. We test this on galaxies up to z ~ 6 and consider potential low metallicity effect.

　　时    间：2014年7月18日（星期五）上午 10：00

　　地    点：紫台办公楼619 会议室

　　联 系 人：马红君 （83332210）

欢迎大家积极参加！

　　                                         紫金山天文台学术委员会