paper

ALMA Sub-arcsec-resolution 183 GHz H2O and Dense Molecular Line Observations of Nearby Ultraluminous Infrared Galaxies

arXiv:2111.09338 · doi:10.3847/1538-4357/ac3a68

Abstract

We present the results of ALMA 2 mm, 1-resolution observations of ten (ultra)luminous infrared galaxies ([U]LIRGs; infrared luminosity 10L) at 0.15, targeting dense (10 cm) molecular (HCN, HCO, and HNC J=2-1) and 183 GHz HO 3-2 emission lines. Higher HCN to HCO J=2-1 flux ratios are observed in some, but not all, AGN-important ULIRGs than in starburst-classified sources. We detect 183 GHz HO emission in almost all AGN-important ULIRGs, and elevated HO emission is found in two sources with elevated HCN J=2-1 emission, relative to HCO J=2-1. Except one ULIRG (the Superantennae), the HO emission largely comes from the entire nuclear regions (1 kpc), rather than AGN-origin megamaser at the very center (1 kpc). Nuclear (1 kpc) dense molecular gas mass derived from HCO J=2-1 luminosity is a few 10M, and its depletion time is estimated to be 10 yr in all sources. Vibrationally excited J=2-1 emission lines of HCN and HNC are detected in a few (U)LIRGs, but those of HCO are not. It is suggested that in mid-infrared-radiation-exposed innermost regions around energy sources, HCO and HNC are substantially less abundant than HCN. In our ALMA 2 mm data of ten (U)LIRGs, two continuum sources are serendipitously detected within 10, which are likely to be an infrared luminous dusty galaxy at 1 and a blazar.

50 pages, 16 Figures. ApJ accepted

References in corpus (46)

Cited by in corpus (4)