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Title: Early Lightcurves of Type Ia Supernovae Are Consistent with Nondegenerate Progenitor Companions
Abstract If Type Ia supernovae (SNe Ia) result from a white dwarf being ignited by Roche-lobe overflow from a nondegenerate companion, then as the SN explosion runs into the companion star its ejecta will be shocked, causing an early blue excess in the lightcurve. A handful of these excesses have been found in single-object studies, but inferences about the population of SNe Ia as a whole have been limited because of the rarity of multiwavelength follow-up within days of explosion. Here we present a 3 yr investigation yielding a nearly unbiased sample of nine nearby (z < 0.01) SNe Ia with exemplary early data. The data are multiwavelength, coveringUBVgriand Neil Gehrels Swift Observatory UV bandpasses, and also early, with an average first epoch 16.0 days before maximum light. Of the nine objects, three show early blue excesses. We do not find enough statistical evidence to reject the null hypothesis that SNe Ia predominantly arise from Roche-lobe-overflowing single-degenerate systems (p= 0.94). When looking at the objects’ colors, we find the objects are almost uniformly near-UV–blue, in contrast to earlier literature samples which found that only a third of SNe Ia are near-UV–blue, and we find a seemingly continuous range ofB − Vcolors in the days after explosion, again in contrast with earlier claims in the literature. This study highlights the importance of early, multiwavelength, high-cadence data in determining the progenitor systems of SNe Ia and in revealing their diverse early behavior.  more » « less
Award ID(s):
1911151 1911225
PAR ID:
10653556
Author(s) / Creator(s):
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; more » ; « less
Publisher / Repository:
ApJ
Date Published:
Journal Name:
The Astrophysical Journal
Volume:
994
Issue:
1
ISSN:
0004-637X
Page Range / eLocation ID:
87
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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