Abstract
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 ≃ −19.3 mag 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.
Highlights
Core-collapse supernovae (SNe) are a diverse and heterogeneous population of events, with the variety of observed sub-types reflecting the complexity of their possible progenitor systems and astrophysics
We have shown that the r-band peak of DES14X2fna shows close resemblance to the R-band peak of SN 1998bw, potentially suggesting that they share a source of luminosity at this phase of the light curve
DES14X2fna is an unusual SN IIb with both a very high peak luminosity and very fast late-time decline compared to other SNe IIb
Summary
Core-collapse supernovae (SNe) are a diverse and heterogeneous population of events, with the variety of observed sub-types reflecting the complexity of their possible progenitor systems and astrophysics. Some SNe IIb (e.g. 1993J, Richmond et al 1994; 2016gkg, Arcavi et al 2017b; Bersten et al 2018) exhibit an initial peak in their light curves, which has been attributed to postshock-breakout cooling in the case of a progenitor with a compact core surrounded by extended, low-mass material (Bersten et al 2012; Nakar & Piro 2014) This typically occurs over a short period of a few days, and is not observed in all SNe IIb (e.g. SN 2008ax; Pastorello et al 2008), potentially because the SN is not discovered until after this phase.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
