An ALMA view on the compact obscured nuclei of luminous IR galaxies

Until recently, the study of the molecular interstellar medium of galaxies has been mostly focused on a few, relatively abundant, molecular species. Recent attempts at modeling the molecular emission of active galaxies have shown that standard high-density tracers do not provide univocal results and are not able to discriminate between different relevant environments (e.g., star-formation vs AGN). Spectral lines surveys allow us to explore the richness of the molecular spectrum of galaxies, provide tighter constrains to astrochemical models, and find new more sensitive tracers of specific gas properties. What started as a time-consuming pioneering work has become now routinely accessible with the advent of ALMA. Here I report the results of the first ALMA spectral scan of an obscured luminous infrared galaxy (LIRG), NGC 4418. The galaxy has a very compact IR core and narrow emission lines that make it the perfect target for the study of vibrationally excited molecules. More than 200 emission lines from 40 molecular species were identified and modeled via an LTE and NLTE analysis. The molecular excitation and abundances derived offer a unique insight into the chemistry of obscured LIRGs.
20/11/2014 - 13:00
Francesco Costagliola