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SHAO Astrophysics Colloquium

Title: An ALMA View of Local Luminous Infrared Galaxies/Quasars

Speaker: Yu GAO (高煜), Purple Mountain Observatory

Time: 3:00 pm, Nov. 14th (Thursday)

Location: Lecture Hall, 3rd floor

Abstract: After a brief overview on the current millimeter (mm)/submm interferometers, we quickly go over the roadmaps leading to the ALMA. We then present a summary of our ALMA CO(6-5) imaging observations in 6 nearby luminous infrared (IR) galaxies (LIRGs) as well as CO(1-0) maps in 8 local IR quasars. CO(6-5) probes the warm and dense molecular gas and shows the tightest linear correlations with the far-IR (i.e., the star formation rate, SFR), whereas CO(1-0) traces the total molecular gas with a nonlinear relationship with the SFR (aka, the Kennicutt-Schmidt laws) in galaxies. Our ALMA images with superb angular resolutions explore the physical conditions in cold dust and warm/dense molecular gas at a spatial resolution on the characteristic size-scale of giant molecular clouds in LIRGs. A variety of CO(6-5) morphology and kinematics in nuclear regions — from clumpy “chaotic” ~kpc disk with starburst ring to compact AGN/starburst and that with possible warm/dense gas outflows — reveals the complex process in the fueling dense molecular gas into central nuclear regions, the heating/cooling of the gas and dust, and the feeding the compact starbursts/AGNs in LIRGs. CO(1-0) observations of IR QSOs reveal a wide diversity of CO distribution and kinematics of their host galaxies: about half of them show rotating disks yet the merging is also still ongoing in some host galaxies of IR QSOs. We finally discuss these in the ‘standard’ evolution scenario from gas-rich mergers to quasars.

 
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The Astrophysics division is the main group engaged in astrophysical research at Shanghai Astronomical Observatory. Research areas include active galactic nuclei and high energy astrophysics, galaxy formation and evolution, cosmology and large scale structure, star clusters and the structure of the Milk Way, star formation, and planetary astrophysics. There are now 45 faculty members, 6 postdocs, and 65 graduate students in the division.

The Astrophysics division maintains close partnerships with many astronomical research institutes, including the joint Key laboratory of research in galaxies and cosmology of CAS with University of Science and Technology of China, the joint astrophysics center with Xiamen University. Members of the astrophysics division also participate in many international and domestic astronomical projects, including LAMOST, HXMT, FAST, the Sloan Digital Sky Survey IV, TMT, LSST, etc.

 

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