Panning for gold, but finding helium: Discovery of the ultra-stripped supernova SN 2019wxt from gravitational-wave follow-up observations
Journal article, 2023
We present the results from multi-wavelength observations of a transient discovered during an intensive follow-up campaign of S191213g, a gravitational wave (GW) event reported by the LIGO-Virgo Collaboration as a possible binary neutron star merger in a low latency search. This search yielded SN 2019wxt, a young transient in a galaxy whose sky position (in the 80% GW contour) and distance (∼150 Mpc) were plausibly compatible with the localisation uncertainty of the GW event. Initially, the transienta's tightly constrained age, its relatively faint peak magnitude (Mi ∼ -16.7 mag), and the r-band decline rate of ∼1 mag per 5 days appeared suggestive of a compact binary merger. However, SN 2019wxt spectroscopically resembled a type Ib supernova, and analysis of the optical-near-infrared evolution rapidly led to the conclusion that while it could not be associated with S191213g, it nevertheless represented an extreme outcome of stellar evolution. By modelling the light curve, we estimated an ejecta mass of only ∼0.1 M·, with 56Ni comprising ∼20% of this. We were broadly able to reproduce its spectral evolution with a composition dominated by helium and oxygen, with trace amounts of calcium. We considered various progenitor channels that could give rise to the observed properties of SN 2019wxt and concluded that an ultra-stripped origin in a binary system is the most likely explanation. Disentangling genuine electromagnetic counterparts to GW events from transients such as SN 2019wxt soon after discovery is challenging: in a bid to characterise this level of contamination, we estimated the rate of events with a volumetric rate density comparable to that of SN 2019wxt and found that around one such event per week can occur within the typical GW localisation area of O4 alerts out to a luminosity distance of 500 Mpc, beyond which it would become fainter than the typical depth of current electromagnetic follow-up campaigns.
Gravitational waves
Supernovae: individual: SN2019wxt
Binaries: general
Stars: evolution
Supernovae: general
Author
I. Agudo
Institute of Astrophysics of Andalusia (IAA)
L. Amati
Istituto nazionale di astrofisica (INAF)
T. An
Shanghai Astronomical Observatory
F. E. Bauer
Pontificia Universidad Catolica de Chile
S. Benetti
Istituto nazionale di astrofisica (INAF)
M.G. Bernardini
Istituto nazionale di astrofisica (INAF)
R. J. Beswick
University of Manchester
K. Bhirombhakdi
Space Telescope Science Institute (STScI)
T. De Boer
University of Hawaii
M. Branchesi
Gran Sasso Science Institute (GSSI)
S.J. Brennan
University College Dublin
E. Brocato
Istituto nazionale di astrofisica (INAF)
M.D. Caballero-García
Institute of Astrophysics of Andalusia (IAA)
E. Cappellaro
Istituto nazionale di astrofisica (INAF)
N. Castro Rodríguez
Instituto de Astrofísica de Canarias
A.J. Castro-Tirado
Institute of Astrophysics of Andalusia (IAA)
K.C. Chambers
University of Hawaii
E. Chassande-Mottin
APC - AstroParticule et Cosmologie
S. Chaty
APC - AstroParticule et Cosmologie
T.-W. Chen
Oskar Klein Centre
A. Coleiro
APC - AstroParticule et Cosmologie
S. Covino
Istituto nazionale di astrofisica (INAF)
F. Da'ammando
Istituto di Radioastronomia
P. Da'avanzo
Istituto nazionale di astrofisica (INAF)
V. Da'elia
Osservatorio Astronomico di Roma
A. Fiore
Istituto nazionale di astrofisica (INAF)
A. Flörs
Helmholtz
M Fraser
University College Dublin
S. Frey
Hungarian Academy of Sciences
C. Frohmaier
University of Southampton
M. Fulton
Queen's University Belfast
L. Galbany
Institute of Space Sciences (ICE) - CSIC
C. Gall
Niels Bohr Institute
H. Gao
University of Hawaii
Jorge García-Rojas
Instituto de Astrofísica de Canarias
G. Ghirlanda
Istituto nazionale di astrofisica (INAF)
S. Giarratana
Istituto di Radioastronomia
J.H. Gillanders
Queen's University Belfast
M. Giroletti
Istituto di Radioastronomia
B.P. Gompertz
University of Birmingham
M. Gromadzki
University of Warsaw
K. E. Heintz
Cosmic Dawn Center (DAWN)
J. Hjorth
Niels Bohr Institute
Y.-D. Hu
Institute of Astrophysics of Andalusia (IAA)
M.E. Huber
University of Hawaii
A. Inkenhaag
Radboud University
L. Izzo
Niels Bohr Institute
Z.P. Jin
Chinese Academy of Sciences
P. G. Jonker
Radboud University
D.A. Kann
Institute of Astrophysics of Andalusia (IAA)
E.C. Kool
Oskar Klein Centre
R Kotak
University of Turku
G. Leloudas
Technical University of Denmark (DTU)
Andrew Levan
Radboud University
C. C. Lin
University of Hawaii
J.D. Lyman
The University of Warwick
E.A. Magnier
University of Hawaii
K. Maguire
Trinity College Dublin
I. Mandel
Monash University
B. Marcote
Joint Institute for VLBI in Europe (JIVE)
D. Mata Sánchez
Instituto de Astrofísica de Canarias
S. Mattila
University of Turku
A. Melandri
Istituto nazionale di astrofisica (INAF)
M.J. Michaåà  Owski
Adam Mickiewicz University in Poznań
J. Moldon
Institute of Astrophysics of Andalusia (IAA)
M. Nicholl
University of Birmingham
A. Nicuesa Guelbenzu
Thüringer Landessternwarte Tautenburg
S.R. Oates
University of Birmingham
F. Onori
Istituto nazionale di astrofisica (INAF)
M. Orienti
Istituto di Radioastronomia
R. Paladino
Istituto di Radioastronomia
Z. Paragi
Joint Institute for VLBI in Europe (JIVE)
M.A. Pérez-Torres
Institute of Astrophysics of Andalusia (IAA)
E. Pian
Istituto nazionale di astrofisica (INAF)
G. Pignata
Millennium Institute of Astrophysics
S. Piranomonte
Osservatorio Astronomico di Roma
J. Quirola-Vásquez
Pontificia Universidad Catolica de Chile
F. Ragosta
Osservatorio Astronomico di Roma
A. Rau
Max Planck Society
S. Ronchini
Gran Sasso Science Institute (GSSI)
A. Rossi
Istituto nazionale di astrofisica (INAF)
R. Sánchez-Ramírez
Institute of Astrophysics of Andalusia (IAA)
O. S. Salafia
Istituto nazionale di astrofisica (INAF)
S. Schulze
Oskar Klein Centre
S. J. Smartt
Queen's University Belfast
K.W. Smith
Queen's University Belfast
J Sollerman
Oskar Klein Centre
S. Srivastav
Queen's University Belfast
R. L. C. Starling
University Of Leicester
D. Steeghs
The University of Warwick
H.F. Stevance
Queen's University Belfast
Nial R. Tanvir
University Of Leicester
Vincenzo Testa
Osservatorio Astronomico di Roma
M.A.P. Torres
Instituto de Astrofísica de Canarias
A. Valeev
Russian Academy of Sciences
S. D. Vergani
Observatoire de Paris-Meudon
D. Vescovi
Goethe University Frankfurt
R. Wainscost
University of Hawaii
D. Watson
Cosmic Dawn Center (DAWN)
K. Wiersema
The University of Warwick
Lukasz Wyrzykowski
University of Warsaw
Jun Yang
Chalmers, Space, Earth and Environment, Onsala Space Observatory
S. Yang
Oskar Klein Centre
D.R. Young
Queen's University Belfast
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 675 A201Subject Categories
Astronomy, Astrophysics and Cosmology
DOI
10.1051/0004-6361/202244751