Astrophys. J., 918, 89-89 (2021/September-2)
The nickel mass distribution of stripped-envelope supernovae: implications for additional power sources.
AFSARIARDCHI N., DROUT M.R., KHATAMI D.K., MATZNER C.D., MOON D.-S. and NI Y.Q.
Abstract (from CDS):
We perform a systematic study of the 56Ni mass (MNi) of 27 stripped-envelope supernovae (SESNe) by modeling their light-curve tails, highlighting that use of "Arnett's rule" overestimates MNi for SESNe by a factor of ∼2. Recently, Khatami & Kasen presented a new model relating the peak time (tp) and luminosity (Lp) of a radioactively powered supernova to its MNi that addresses several limitations of Arnett-like models, but depends on a dimensionless parameter, β. Using observed tp, Lp, and tail-measured MNi values for 27 SESNe, we observationally calibrate β for the first time. Despite scatter, we demonstrate that the model of Khatami & Kasen with empirically calibrated β values provides significantly improved measurements of MNi when only photospheric data are available. However, these observationally constrained β values are systematically lower than those inferred from numerical simulations, primarily because the observed sample has significantly higher (0.2-0.4 dex) Lp for a given MNi. While effects due to composition, mixing, and asymmetry can increase Lp none can explain the systematically low β values. However, the discrepancy can be alleviated if ∼7%-50% of Lp for the observed sample comes from sources other than radioactive decay. Either shock cooling or magnetar spin-down could provide the requisite luminosity. Finally, we find that even with our improved measurements, the MNi values of SESNe are still a factor of ∼3 larger than those of hydrogen-rich Type II SNe, indicating that these supernovae are inherently different in terms of the initial mass distributions of their progenitors or their explosion mechanisms.
© 2021. The American Astronomical Society. All rights reserved.
Supernovae - Core-collapse supernovae
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