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 M-r similar or equal to -19.3 mag 20 d after explosion. This object does not show a linear decline tail in the light curve until similar or equal to 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 Ni-56 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 similar to 1.1-2.4 percent of cases in DES, depending on the probability threshold used for a positive classification.

Understanding the extreme luminosity of DES14X2fna

Costanzi, M.;
2021-01-01

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 M-r similar or equal to -19.3 mag 20 d after explosion. This object does not show a linear decline tail in the light curve until similar or equal to 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 Ni-56 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 similar to 1.1-2.4 percent of cases in DES, depending on the probability threshold used for a positive classification.
2021
Pubblicato
https://academic.oup.com/mnras/article/505/3/3950/6283733#332891567
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11368/2993672
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