题　  目：Warm Molecular Gas in Luminous Infrared Galaxies: Gas and Dust Heating, and the Roles of Star Formation and AGN

报 告 人: Dr. Nanyao Lu(吕南姚，California Institute of Technology)

Abstract: We describe a Herschel/SPIRE 194-671 micron spectroscopic survey of a flux-limited sample of 125 local luminous infrared galaxies (LIRGs).  The survey generated rich data on molecular line emission, including detections in almost every target of (i) the CO rotational line emission from warm and dense molecular gas, (ii) the [NII] 205 micro line from ionized gas, and (iii) the [CI] 370 and/or 609 micron lines arising mainly from less dense molecular gas where low-J CO lines arise.  We present our observational results and statistical correlations among CO line luminosities, IR dust luminosity and color, and whether a target is known to harbor an AGN or not.  We show that an increasing [NII] 205 micro to a mid-J CO line ratio traces galaxies of increasingly denser gas and/or more intense UV radiation field.  Our CO data show (a) that for most LIRGS, there is a remarkable proportionality between molecular gas heating and total dust heating, suggesting a star formation-dominated case where CO line emission occurs primarily at mid J levels (i.e., 4 < J < 10), and (b) that an AGN heats CO gas to emit lines primarily at higher J levels.  As a result, the mid-J CO line emission can provide a robust tool to separate starburst-dominated from AGN-dominated galaxies, and to observationally quantify the fractional luminosity of the dust emission that is due to AGN heating.

时　  间：7月29日（周一）上午10:00

地　  点：苏福特一楼会议室

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