The Nickel Mass Distribution of Stripped-Envelope Supernovae: Implications for Additional Power Sources. (arXiv:2009.06683v2 [astro-ph.HE] UPDATED)
<a href="http://arxiv.org/find/astro-ph/1/au:+Afsariardchi_N/0/1/0/all/0/1">Niloufar Afsariardchi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Drout_M/0/1/0/all/0/1">Maria R. Drout</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Khatami_D/0/1/0/all/0/1">David Khatami</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Matzner_C/0/1/0/all/0/1">Christopher D. Matzner</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Moon_D/0/1/0/all/0/1">Dae-Sik Moon</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ni_Y/0/1/0/all/0/1">Yuan Qi Ni</a>
We perform a systematic study of the $^{56}$Ni mass ($M_{rm Ni}$) of 27
stripped envelope supernovae (SESNe) by modeling their light-curve tails,
highlighting that use of “Arnett’s rule” overestimates $M_{rm Ni}$ for SESN
by a factor of $sim$2. Recently, citet{Khatami2019} presented a new model
relating the peak time ($t_{rm p}$) and luminosity ($L_{rm p}$) of a
radioactive-powered SN to its $M_{rm Ni}$ that addresses several limitations
of Arnett-like models, but depends on a dimensionless parameter, $beta$. Using
observed $t_{rm p}$, $L_{rm p}$, and tail-measured $M_{rm Ni}$ values for 27
SESN, we observationally calibrate $beta$ for the first time. Despite scatter,
we demonstrate that the model of citet{Khatami2019} with
empirically-calibrated $beta$ values provides significantly improved
measurements of $M_{rm Ni}$ when only photospheric data is available. However,
these observationally-constrained $beta$ values are systematically lower than
those inferred from numerical simulations, primarily because the observed
sample has significantly higher (0.2-0.4 dex) $L_{rm p}$ for a given $M_{rm
Ni}$. While effects due to composition, mixing, and asymmetry can increase
$L_{rm p}$ current models cannot explain the systematically low $beta$
values. However, the discrepancy can be alleviated if $sim$7–50% of $L_{rm
p}$ for the observed sample originates from sources other than $^{56}$Ni.
Either shock cooling or magnetar spin-down could provide the requisite
luminosity. Finally, we find that even with our improved measurements, the
$M_{rm Ni}$ values of SESN are still a factor of $sim$3 larger than those of
hydrogen-rich Type II SN, indicating that these supernovae are inherently
different in terms of their progenitor initial mass distributions or explosion
mechanisms.
We perform a systematic study of the $^{56}$Ni mass ($M_{rm Ni}$) of 27
stripped envelope supernovae (SESNe) by modeling their light-curve tails,
highlighting that use of “Arnett’s rule” overestimates $M_{rm Ni}$ for SESN
by a factor of $sim$2. Recently, citet{Khatami2019} presented a new model
relating the peak time ($t_{rm p}$) and luminosity ($L_{rm p}$) of a
radioactive-powered SN to its $M_{rm Ni}$ that addresses several limitations
of Arnett-like models, but depends on a dimensionless parameter, $beta$. Using
observed $t_{rm p}$, $L_{rm p}$, and tail-measured $M_{rm Ni}$ values for 27
SESN, we observationally calibrate $beta$ for the first time. Despite scatter,
we demonstrate that the model of citet{Khatami2019} with
empirically-calibrated $beta$ values provides significantly improved
measurements of $M_{rm Ni}$ when only photospheric data is available. However,
these observationally-constrained $beta$ values are systematically lower than
those inferred from numerical simulations, primarily because the observed
sample has significantly higher (0.2-0.4 dex) $L_{rm p}$ for a given $M_{rm
Ni}$. While effects due to composition, mixing, and asymmetry can increase
$L_{rm p}$ current models cannot explain the systematically low $beta$
values. However, the discrepancy can be alleviated if $sim$7–50% of $L_{rm
p}$ for the observed sample originates from sources other than $^{56}$Ni.
Either shock cooling or magnetar spin-down could provide the requisite
luminosity. Finally, we find that even with our improved measurements, the
$M_{rm Ni}$ values of SESN are still a factor of $sim$3 larger than those of
hydrogen-rich Type II SN, indicating that these supernovae are inherently
different in terms of their progenitor initial mass distributions or explosion
mechanisms.
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