8-12 juin, 2014


Luminous Infrared Galaxies through the Eyes of Modern Submillimeter Interferometers

Kazimierz Sliwa (McMaster University)

Christine Wilson (McMaster University)

Luminous Infrared Galaxies (LIRGs) allow us to study the most extreme modes of star formation in the local universe. The burst of star formation is believed to be triggered by the merger of two gas-rich galaxies. The Submillimeter Array (SMA) sample of Wilson et al. (2008) consists of 14 local (D < 200 Mpc) LIRGs of varying merger stages allowing us to study the evolution of the molecular gas, the fuel for star formation, along the merger process. We are using high-resolution 12^CO and 13^CO observations to constrain the physical conditions (temperature, density, column density, etc.) of the molecular gas of the sample via a radiative transfer analysis. For VV 114, we obtained new 13^CO J=1-0 ALMA observations and combined it with the 13^CO J=2-1 SMA observations to constrain the 12^CO-to-13^CO abundance ratio ([12^CO]/[13^CO]) of a LIRG for the first time, using high-resolution observations. We find an unusually high [12^CO]/[13^CO] ratio, roughly 3 times that of the local ISM value, which may have been caused by an inflow of pristine molecular gas from the outskirts of the merging systems and/or increased production of 12^C from the ongoing starburst. We will also present new results for NGC 1614, adding new CARMA 12^CO and 13^CO J=1-0, and ALMA 12^CO J=3-2 and J=6-5 observations into the radiative transfer analysis. We will constrain [12^CO]/[13^CO] and measure the highly debated 12^CO-to-H_2 conversion factor, alpha_CO, to compare to VV 114 and Arp 299. The ALMA 12^CO J=6-5 observations will be used to look for evidence of a hot molecular gas component as seen for other starburst systems like M82, Arp 220 and the Antennae.
(doit être confirmé par le SOC)