iPTF16abc and the population of Type Ia supernovae: comparing the photospheric, transitional, and nebular phases

Abstract

Key information about the progenitor system and the explosion mechanism of Type Ia supernovae (SNe Ia) can be obtained from early observations, within a few days from explosion. iPTF16abc was discovered as a young SN Ia with excellent early time data. Here, we present photometry and spectroscopy of the SN in the nebular phase. A comparison of the early time data with a sample of SNe Ia shows distinct features, differing from normal SNe Ia at early phases but similar to normal SNe Ia at a few weeks after maximum light (i.e. the transitional phase) and well into the nebular phase. The transparency timescales (t 0 ) for this sample of SNe Ia range between ∼ 25 and 41 days indicating a diversity in the ejecta masses. t 0 also weakly correlates with the peak bolometric luminosity, consistent with the interpretation that SNe with higher ejecta masses would produce more 56 Ni . Comparing the t 0 and the maximum luminosity, L max distribution of a sample of SNe Ia to predictions from a wide range of explosion models we find an indication that the sub-Chandrasekhar mass models span the range of observed values. However, the bright end of the distribution can be better explained by Chandrasekhar mass delayed detonation models, hinting at multiple progenitor channels to explain the observed bolometric properties of SNe Ia. iPTF16abc appears to be consistent with the predictions from the M ch models.

Anomaly Detection in the Open Supernova Catalog

“…11). The transitional and nebular spectrum of SN2016bln appear similar to the normal SN2011fe as well as to over-luminous SNe 1991T and 1999aa [103]. a peculiar rise time, non-evolving blue colour, and unusual strong C II absorption.…”

Characterizing the secondary maximum in the r-band for Type Ia supernovae: diagnostic for the ejecta mass

“…In previous works a direct comparison of the model predictions for t 0 versus other global properties (e.g. 56 Ni mass) has been important to suggest that multiple progenitor channels could be contributing to the observed diversity of SNe Ia (Scalzo et al 2014;Childress, et al 2015;Wygoda, Elbaz & Katz 2017;Dhawan, et al 2018). Additionally, studies have compared different properties of SNe Ia (e.g.…”

“…We add an error of 2 days to the error from the fit of t 0 , corresponding to the average error in inferring the rise time of an SN Ia (see Scalzo et al 2014, for details). The bolometric light curve is created from the multi-band photometry using the method described in Dhawan, et al (2018). We convert the observed magnitudes to de-reddened fluxes and interpolate the filters onto the same time step.…”

Holismokes

“…The second LSN, iPTF16geu, was discovered by Goobar et al (2017) and is a type Ia supernova (SN Ia) at redshift 0.409 lensed by a galaxy at a redshift of 0.216. Several lensing studies on SN Refsdal have been performed (e.g., Rodney et al 2016;Kelly et al 2016b;Treu et al 2016;Pierel & Rodney 2019;Grillo et al 2016Grillo et al , 2020Baklanov et al 2021); iPTF16geu has been studied extensively (Goobar et al 2017;More et al 2017;Yahalomi et al 2017;Dhawan et al 2018;Johansson et al 2021) and shows strong signs of microlensing. Further studies on SNe Ia and their usability to measure time delays have been conducted by Goldstein et al (2018), Foxley-Marrable et al (2018), Huber et al (2019Huber et al ( , 2021.…”