ALMA observations of molecular gas in the host galaxy of AT2018cow

Abstract

We investigate the molecular gas in, and star-formation properties of, the host galaxy (CGCG 137-068) of a mysterious transient, AT2018cow, at kpc and larger scales, using archival band-3 data from the Atacama Large Millimeter/submillimeter Array (ALMA). AT2018cow is the nearest Fast-Evolving Luminous Transient (FELT), and this is the very first study unveiling molecular-gas properties of FELTs. The achieved rms and beam size are 0.21 mJy beam${}^{-1}$ at a velocity resolution of $40$ km s${}^{-1}$ and $3".66\times 2".71$ ($1.1\mathrm{kpc}\times 0.8\mathrm{kpc}$), respectively. CO($J$=1-0) emission is successfully detected. The total molecular gas mass inferred from the CO data is $(1.85\pm 0.04)\times 10^8$ M${}_{\odot }$ with the Milky Way CO-to-H${}_2$ conversion factor. The H${}_2$ column density at the AT2018cow site is estimated to be $8.6\times 10^{20}$ cm${}^{-2}$. The ALMA data reveal that (1) CGCG 137-068 is a normal star-forming (SF) dwarf galaxy in terms of its molecular gas and star-formation properties and (2) AT2018cow is located between a CO peak and a blue star cluster. These properties suggest on-going star formation and favor the explosion of a massive star as the progenitor of AT2018cow. We also find that CGCG 137-068 has a solar or super-solar metallicity. If the metallicity of the other FELT hosts is not higher than average, then some property of SF dwarf galaxies other than metallicity may be related to FELTs.

8 pages, 3 figures, 2 tables, accepted for publication in ApJL

References in corpus (12)

• A Highly Consistent Framework for the Evolution of the Star-Forming "Main Sequence" from z~0-6
• xCOLD GASS: the complete IRAM-30m legacy survey of molecular gas for galaxy evolution studies
• An ultraviolet-optical flare from the tidal disruption of a helium-rich stellar core
• A Continuum of H- to He-Rich Tidal Disruption Candidates With a Preference for E+A Galaxies
• Rapidly-Evolving and Luminous Transients from Pan-STARRS1
• Measured Metallicities at the Sites of Nearby Broad-Lined Type Ic Supernovae and Implications for the SN-GRB Connection
• Constraints on core-collapse supernova progenitors from correlations with H-alpha emission
• On the association between core-collapse supernovae and HII regions
• The Post-Starburst Evolution of Tidal Disruption Event Host Galaxies
• Supernovae and their host galaxies - II. The relative frequencies of supernovae types in spirals
• HI 21cm mapping of the host galaxy of AT2018cow: a fast-evolving luminous transient within a ring of high column density gas
• Molecular Gas Properties in the Host Galaxy of GRB080207

Cited by in corpus (9)

• A Blast from the Pasture: Studying the environment of AT 2018cow with MUSE
• The Host Galaxies of Rapidly Evolving Transients in the Dark Energy Survey
• An environmental analysis of the fast transient AT2018cow and implications for its progenitor and late-time brightness
• A possible 250-second X-ray quasi-periodicity in the fast blue optical transient AT2018cow
• Late-time Hubble Space Telescope Observations of AT 2018cow. I. Further Constraints on the Fading Prompt Emission and Thermal Properties 50--60 Days Post-discovery
• Real-time Discovery of AT2020xnd: A Fast, Luminous Ultraviolet Transient with Minimal Radioactive Ejecta
• Spatially Resolved Molecular Gas Properties of Host Galaxy of Type I Superluminous Supernova SN 2017egm
• The interstellar medium in the environment of the supernova-less long-duration GRB 111005A
• Diverse Properties of Molecular Gas in the Host Galaxies of Fast Radio Bursts