J/A+A/627/A106 HI observations of AT 2018cow (Michalowski+, 2019)
Nature of the unusual transient AT 2018cow from HI observations
of its host galaxy.
Michalowski M. J., Kamphuis P., Hjorth J., Kann D. A.,
de Ugarte Postigo A., Galbany L., Fynbo J. P. U., Ghosh A., Hunt L. K.,
Kuncarayakti H., Le Flo'h E., Lesniewska A., Misra K.,
Nicuesa Guelbenzu A., Palazzi E., Rasmussen J., Resmi L., Rossi A.,
Savaglio S., Schady P., Schulze S., Thone C. C., Watson D., Jozsa G. I. G.,
Serra P., Smirnov O. M.
<Astron. Astrophys. 627, A106 (2019)>
=2019A&A...627A.106M 2019A&A...627A.106M (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, optical ; Galaxies, radio ; H I data ; Interferometry ;
Interstellar medium ; Radio continuum ; Radio lines ; Supernovae
Keywords: dust, extinction - galaxies: individual: CGCG137-068 -
galaxies: ISM - galaxies: star formation -
radio lines: galaxies - supernovae: individual: AT 2018cow
Abstract:
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 AT2018cow 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 AT2018cow host with
the Giant Metrewave Radio Telescope. There is no unusual atomic gas
concentration near the position of AT2018cow. The gas distribution is
much more regular than those of GRB/SN hosts. The AT2018cow host has
an atomic gas mass lower by 0.24dex than predicted from its star
formation rate (SFR) and is at the lower edge of the galaxy main
sequence. In the continuum we detected the emission of AT2018cow and
of a star-forming region in the north-eastern part of the bar (away
from AT2018cow). This region hosts a third of the galaxy's SFR. The
absence of atomic gas concentration close to AT2018cow, along with a
normal SFR and regular HI velocity field, sets CGCG137-068 apart from
GRB/SN hosts studied in HI. The environment of AT2018cow 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.
We interpret the recently reported atomic gas ring in CGCG137-068 as a
result of internal processes connected with gravitational resonances
caused by the bar.
Description:
GMRT HI data for CGCG137-068, AT2018cow host.
Objects:
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RA (2000) DE Designation(s)
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16 16 00.2 +22 16 04.9 AT 2018cow = SN 2018cow
16 16 00.6 +22 16 08.0 CGCG137-068 = Z 137-68
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 180 17 List of fits images and datacubes
fits/* . 17 Individual fits images and datacubes
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
10- 18 F9.5 deg DEdeg Declination of center (J2000)
20- 23 I4 --- Nx Number of pixels along X-axis
25- 28 I4 --- Ny Number of pixels along Y-axis
30- 31 I2 --- Nz ? Number of slices, for the datacubes
33- 58 A26 "datime" Obs.date Observation date
60- 70 E11.6 Hz bFreq ? Lower value of frequency interval,
for the datacubes
72- 82 E11.6 Hz BFreq ? Upper value of frequency interval,
for the datacubes
84- 90 F7.1 Hz dFreq ? Frequency resolution, for the datacubes
92- 97 I6 Kibyte size Size of FITS file
99-134 A36 --- FileName Name of FITS file, in subdirectory fits
136-180 A45 --- Title Title of the FITS file
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Acknowledgements:
Michal Michalowski, mj.michalowski(at)gmail.com
(End) Michal Michalowski [AMU, Poznan, PL], Patricia Vannier [CDS] 21-Jun-2019