H I 21 cm mapping of the host galaxy of AT2018cow: a fast-evolving luminous transient within a ring of high column density gas
Abstract
We report Giant Metrewave Radio Telescope H I 21 cm imaging of CGCG 137-068, the host galaxy of the fast-evolving luminous transient (FELT) AT2018cow. This is the first study of the gas properties of a FELT host galaxy. We obtain a total H I mass of (6.6 ± 0.9) × 108 M⊙ for the host galaxy, which implies an atomic gas depletion time of 3 Gyr and a gas-to-stellar mass ratio of 0.47, consistent with values in normal star-forming dwarf galaxies. At spatial resolutions of ≥6 kpc, the H I of CGCG 137-068 appears to be distributed in a disc, in mostly regular rotation. However, at spatial resolutions of 2 kpc, the highest column density H I is found to lie in an asymmetric ring around the central regions, with H I column densities ≥1021 cm-2; AT2018cow lies within this high column density ring. This H I ring could be suggestive of an interaction between CGCG 137-068 and a companion galaxy. Such a ring is ideal for the formation of compact regions of star formation hosting massive stars, favouring massive star progenitor models for AT2018cow. We measure a 1.4 GHz flux density of 1.13 ± 0.13 mJy for AT2018cow on 2018 August 27.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- May 2019
- DOI:
- 10.1093/mnrasl/slz035
- arXiv:
- arXiv:1903.00477
- Bibcode:
- 2019MNRAS.485L..93R
- Keywords:
-
- stars: individual: AT2018cow;
- stars: massive;
- galaxies: ISM;
- galaxies: kinematics and dynamics;
- galaxies: star formation;
- radio lines: galaxies;
- Astrophysics - High Energy Astrophysical Phenomena;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- Accepted for publication in MNRAS Letters. For the definitive version visit https://academic.oup.com/mnras. 5 pages, 3 figures, 1 table