Exploring the molecular chemistry and excitation in obscured LIRGs: An ALMA mm-wave spectral scan of NGC 4418

Paper in proceeding, 2016

The compact, obscured nuclei (CON) of luminous infrared galaxies (LIRG) combine large molecular columns with intense infrared (IR), ultra-violet (UV), and X-radiation and represent ideal laboratories for the study of the chemistry of the interstellar medium (ISM) under extreme conditions. Here we present the first ALMA wide-band spectral scan of a dusty LIRG, the CON NGC 4418. We derive molecular abundances and compare them with other Galactic and extragalactic sources. Our spectral scan confirms that the chemical complexity in the nucleus of NGC 4418 is one of the highest ever observed outside our Galaxy. We suggest that the galaxy may be a template for a new kind of chemistry and excitation, typical of CON.