@misc{10481/70465,
year = {2021},
month = {5},
url = {http://hdl.handle.net/10481/70465},
abstract = {We present DES14X2fna, a high-luminosity, fast-declining Type IIb supernova (SN IIb) at redshift z = 0.0453, detected by the
Dark Energy Survey (DES). DES14X2fna is an unusual member of its class, with a light curve showing a broad, luminous peak
reaching Mr   −19.3mag 20 d after explosion. This object does not show a linear decline tail in the light curve until  60 d
after explosion, after which it declines very rapidly (4.30 ± 0.10 mag 100 d−1 in the r band). By fitting semi-analytic models
to the photometry of DES14X2fna, we find that its light curve cannot be explained by a standard 56Ni decay model as this is
unable to fit the peak and fast tail decline observed. Inclusion of either interaction with surrounding circumstellar material or a
rapidly-rotating neutron star (magnetar) significantly increases the quality of the model fit. We also investigate the possibility
for an object similar to DES14X2fna to act as a contaminant in photometric samples of SNe Ia for cosmology, finding that
a similar simulated object is misclassified by a recurrent neural network (RNN)-based photometric classifier as an SN Ia in
∼1.1–2.4 per cent of cases in DES, depending on the probability threshold used for a positive classification.},
organization = {Science and Technology Facilities Council through the DISCnet Centre for Doctoral Training},
organization = {EU/FP7-ERC grant	615929},
organization = {European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant	839090},
organization = {Spanish grant within the European Funds for Regional Development (FEDER)	PGC2018-095317-B-C21},
organization = {United States Department of Energy (DOE)},
organization = {National Science Foundation (NSF)},
organization = {Spanish Government},
organization = {UK Research & Innovation (UKRI)},
organization = {Science & Technology Facilities Council (STFC)},
organization = {UK Research & Innovation (UKRI)},
organization = {Higher Education Funding Council for England},
organization = {National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign},
organization = {Kavli Institute of Cosmological Physics at the University of Chicago},
organization = {Mitchell Institute for Fundamental Physics and Astronomy at Texas AM University},
organization = {Financiadora de Inovacao e Pesquisa (Finep)},
organization = {Fundacao Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio De Janeiro (FAPERJ)},
organization = {Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPQ)},
organization = {Ministerio da Ciencia, Tecnologia e Inovacao},
organization = {German Research Foundation (DFG)},
organization = {Collaborating Institutions in the Dark Energy Survey},
organization = {National Science Foundation (NSF)	AST-1138766	
AST-1536171},
organization = {MINECO	AYA2015-71825	
ESP2015-66861	
FPA2015-68048	
SEV-2016-0588	
SEV-2016-0597	
MDM-2015-0509},
organization = {European Commission},
organization = {CERCA program of the Generalitat de Catalunya},
organization = {European Research Council (ERC)	FP7/2007-2013},
organization = {European Research Council (ERC)
European Commission	240672	
291329	
306478},
organization = {Brazilian Instituto Nacional de Ciencia e Tecnologia (INCT) e-Universe (CNPq grant)	465376/2014-2},
organization = {Fermi Research Alliance, LLC	DE-AC02-07CH11359},
organization = {Anglo-Australian Telescope	A/2013B/012},
organization = {National Aeronautics & Space Administration (NASA)},
publisher = {Oxford University Press},
keywords = {Supernovae: general},
keywords = {Supernovae: individual: DES14X2fna},
title = {Understanding the extreme luminosity of DES14X2fna},
doi = {10.1093/mnras/stab1478},
author = {Grayling, M. and Galbany González, Lluis and DES Collaboration},
}