Understanding the extreme luminosity of DES14X2fna
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Oxford University Press
Supernovae: generalSupernovae: individual: DES14X2fna
M Grayling... [et al.]. Understanding the extreme luminosity of DES14X2fna, Monthly Notices of the Royal Astronomical Society, Volume 505, Issue 3, August 2021, Pages 3950–3967, [https://doi.org/10.1093/mnras/stab1478]
SponsorshipScience and Technology Facilities Council through the DISCnet Centre for Doctoral Training; EU/FP7-ERC grant 615929; European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant 839090; Spanish grant within the European Funds for Regional Development (FEDER) PGC2018-095317-B-C21; United States Department of Energy (DOE); National Science Foundation (NSF); Spanish Government; UK Research & Innovation (UKRI); Science & Technology Facilities Council (STFC); UK Research & Innovation (UKRI); Higher Education Funding Council for England; National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign; Kavli Institute of Cosmological Physics at the University of Chicago; Mitchell Institute for Fundamental Physics and Astronomy at Texas AM University; Financiadora de Inovacao e Pesquisa (Finep); Fundacao Carlos Chagas Filho de Amparo a Pesquisa do Estado do Rio De Janeiro (FAPERJ); Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPQ); Ministerio da Ciencia, Tecnologia e Inovacao; German Research Foundation (DFG); Collaborating Institutions in the Dark Energy Survey; National Science Foundation (NSF) AST-1138766 AST-1536171; MINECO AYA2015-71825 ESP2015-66861 FPA2015-68048 SEV-2016-0588 SEV-2016-0597 MDM-2015-0509; European Commission; CERCA program of the Generalitat de Catalunya; European Research Council (ERC) FP7/2007-2013; European Research Council (ERC) European Commission 240672 291329 306478; Brazilian Instituto Nacional de Ciencia e Tecnologia (INCT) e-Universe (CNPq grant) 465376/2014-2; Fermi Research Alliance, LLC DE-AC02-07CH11359; Anglo-Australian Telescope A/2013B/012; National Aeronautics & Space Administration (NASA)
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.