Constraining Type Ia Supernova Asymmetry with the Gamma Ray Escape Timescale. (arXiv:1901.05057v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Levanon_N/0/1/0/all/0/1">Naveh Levanon</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Soker_N/0/1/0/all/0/1">Noam Soker</a> (Technion, Israel)
We calculate the effects of an asymmetric $^{56}mathrm{Ni}$ distribution in
Type Ia supernova (SN Ia) ejecta on the late light curve ($>40$ days after
peak) using the gamma ray escape timescale ($t_0$) and find it is modest
compared to other possible variations in ejecta structure. We parameterize
asymmetry in the $^{56}mathrm{Ni}$ distribution and calculate $t_0$ for a grid
of SN ejecta models spanning a large volume of the asymmetry parameter space.
The models have spherical density profiles while the $^{56}mathrm{Ni}$
distribution in them has various levels of asymmetry. By placing constraints
based on the observational measurement of $t_0$ and other general properties of
SN Ia ejecta, we find the range of allowed asymmetry in the $^{56}mathrm{Ni}$
distribution. We find that models with a single ejecta mass and varying
$^{56}mathrm{Ni}$ distributions cannot explain the full range of observed
$t_0$ values. This strengthens the claim that both Chandrasekhar mass and
sub-Chandrasekhar mass explosions are required to explain the diversity of SN
Ia observations. We quantify the level of asymmetry in the $^{56}mathrm{Ni}$
distribution that is allowed from the various constraints, and find that some
level of asymmetry in the distribution is not ruled out.
We calculate the effects of an asymmetric $^{56}mathrm{Ni}$ distribution in
Type Ia supernova (SN Ia) ejecta on the late light curve ($>40$ days after
peak) using the gamma ray escape timescale ($t_0$) and find it is modest
compared to other possible variations in ejecta structure. We parameterize
asymmetry in the $^{56}mathrm{Ni}$ distribution and calculate $t_0$ for a grid
of SN ejecta models spanning a large volume of the asymmetry parameter space.
The models have spherical density profiles while the $^{56}mathrm{Ni}$
distribution in them has various levels of asymmetry. By placing constraints
based on the observational measurement of $t_0$ and other general properties of
SN Ia ejecta, we find the range of allowed asymmetry in the $^{56}mathrm{Ni}$
distribution. We find that models with a single ejecta mass and varying
$^{56}mathrm{Ni}$ distributions cannot explain the full range of observed
$t_0$ values. This strengthens the claim that both Chandrasekhar mass and
sub-Chandrasekhar mass explosions are required to explain the diversity of SN
Ia observations. We quantify the level of asymmetry in the $^{56}mathrm{Ni}$
distribution that is allowed from the various constraints, and find that some
level of asymmetry in the distribution is not ruled out.
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