On the nature of the unusual transient AT 2018cow from HI observations of its host galaxy. (arXiv:1902.10144v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Michalowski_M/0/1/0/all/0/1">Michał J. Michałowski</a> (AMU, Poznań), <a href="http://arxiv.org/find/astro-ph/1/au:+Kamphuis_P/0/1/0/all/0/1">P. Kamphuis</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hjorth_J/0/1/0/all/0/1">J. Hjorth</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kann_D/0/1/0/all/0/1">D. A. Kann</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Postigo_A/0/1/0/all/0/1">A. de Ugarte Postigo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Galbany_L/0/1/0/all/0/1">L. Galbany</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Fynbo_J/0/1/0/all/0/1">J. P. U. Fynbo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ghosh_A/0/1/0/all/0/1">A. Ghosh</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hunt_L/0/1/0/all/0/1">L. K. Hunt</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kuncarayakti_H/0/1/0/all/0/1">H. Kuncarayakti</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Floch_E/0/1/0/all/0/1">E. Le Floc'h</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lesniewska_A/0/1/0/all/0/1">A. Leśniewska</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Misra_K/0/1/0/all/0/1">K. Misra</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Guelbenzu_A/0/1/0/all/0/1">A. Nicuesa Guelbenzu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Palazzi_E/0/1/0/all/0/1">E. Palazzi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rasmussen_J/0/1/0/all/0/1">J. Rasmussen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Resmi_L/0/1/0/all/0/1">L. Resmi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Rossi_A/0/1/0/all/0/1">A. Rossi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Savaglio_S/0/1/0/all/0/1">S. Savaglio</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Schady_P/0/1/0/all/0/1">P. Schady</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Schulze_S/0/1/0/all/0/1">S. Schulze</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Thone_C/0/1/0/all/0/1">C. C. Thöne</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Watson_D/0/1/0/all/0/1">D. Watson</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Jozsa_G/0/1/0/all/0/1">G. I. G. Józsa</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Serra_P/0/1/0/all/0/1">P. Serra</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Smirnov_O/0/1/0/all/0/1">O. M. Smirnov</a>
Unusual stellar explosions represent an opportunity to learn about both
stellar and galaxy evolution. Mapping the atomic gas in host galaxies of such
transients can lead to an understanding of the conditions triggering them. We
provide resolved atomic gas observations of the host galaxy, CGCG137-068, of
the unusual, poorly-understood transient AT 2018cow searching for clues to
understand its nature. We test whether it is consistent with a recent inflow of
atomic gas from the intergalactic medium, as suggested for host galaxies of
gamma-ray bursts (GRBs) and some supernovae (SNe). We observed the HI hyperfine
structure line of the AT 2018cow host with the Giant Metrewave Radio Telescope.
There is no atomic gas concentration near the position of AT 2018cow. The gas
distribution is much more regular than those of GRB/SN hosts. The AT 2018cow
host has an atomic gas mass lower by 0.24 dex than predicted from its star
formation rate (SFR) and is at the lower edge of the galaxy main sequence. We
detected two faint HI emitters 100-150 kpc away, but at low significance. In
the continuum we detected the emission of AT 2018cow and of a star-forming
region in the north-eastern part of the bar (away from AT 2018cow). This region
hosts a third of the galaxy’s SFR. The absence of atomic gas close to AT
2018cow, along with a normal SFR and regular HI velocity field, sets
CGCG137-068 apart from GRB/SN hosts studied in HI. The environment of AT
2018cow therefore suggests that its progenitor may not have been a massive
star. Our findings are consistent with an origin of the transient that does not
require a connection between its progenitor and gas concentration or inflow: an
exploding low-mass star, a tidal disruption event, a merger of white dwarfs, or
a merger between a neutron star and a giant star.
Unusual stellar explosions represent an opportunity to learn about both
stellar and galaxy evolution. Mapping the atomic gas in host galaxies of such
transients can lead to an understanding of the conditions triggering them. We
provide resolved atomic gas observations of the host galaxy, CGCG137-068, of
the unusual, poorly-understood transient AT 2018cow searching for clues to
understand its nature. We test whether it is consistent with a recent inflow of
atomic gas from the intergalactic medium, as suggested for host galaxies of
gamma-ray bursts (GRBs) and some supernovae (SNe). We observed the HI hyperfine
structure line of the AT 2018cow host with the Giant Metrewave Radio Telescope.
There is no atomic gas concentration near the position of AT 2018cow. The gas
distribution is much more regular than those of GRB/SN hosts. The AT 2018cow
host has an atomic gas mass lower by 0.24 dex than predicted from its star
formation rate (SFR) and is at the lower edge of the galaxy main sequence. We
detected two faint HI emitters 100-150 kpc away, but at low significance. In
the continuum we detected the emission of AT 2018cow and of a star-forming
region in the north-eastern part of the bar (away from AT 2018cow). This region
hosts a third of the galaxy’s SFR. The absence of atomic gas close to AT
2018cow, along with a normal SFR and regular HI velocity field, sets
CGCG137-068 apart from GRB/SN hosts studied in HI. The environment of AT
2018cow therefore suggests that its progenitor may not have been a massive
star. Our findings are consistent with an origin of the transient that does not
require a connection between its progenitor and gas concentration or inflow: an
exploding low-mass star, a tidal disruption event, a merger of white dwarfs, or
a merger between a neutron star and a giant star.
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