POSSIS: predicting spectra, light curves and polarization for multi-dimensional models of supernovae and kilonovae. (arXiv:1906.04205v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Bulla_M/0/1/0/all/0/1">Mattia Bulla</a>

We present POSSIS, a time-dependent three-dimensional Monte Carlo code for
modelling radiation transport in supernovae and kilonovae. The code
incorporates wavelength- and time-dependent opacities and predicts
viewing-angle dependent spectra, light curves and polarization for both
idealized and hydrodynamical explosion models. We apply the code to a kilonova
model with two distinct ejecta components, one including lanthanide elements
with relatively high opacities and the other devoid of lanthanides and
characterized by lower opacities. We find that a model with total ejecta mass
$M_mathrm{ej}=0.04,M_odot$ and half-opening angle of the lanthanide-rich
component $Phi=30^circ$ provides a good match to GW 170817 / AT 2017gfo for
orientations near the polar axis (i.e. for a system viewed close to face-on).
We then show how crucial is the use of self-consistent multi-dimensional models
in place of combining one-dimensional models to infer important parameters as
the ejecta masses. We finally explore the impact of $M_mathrm{ej}$ and $Phi$
on the synthetic observables and highlight how the relatively fast computation
times of POSSIS make it well-suited to perform parameter-space studies and
extract key properties of supernovae and kilonovae. Spectra calculated with
POSSIS in this and future studies will be made publicly available.

We present POSSIS, a time-dependent three-dimensional Monte Carlo code for
modelling radiation transport in supernovae and kilonovae. The code
incorporates wavelength- and time-dependent opacities and predicts
viewing-angle dependent spectra, light curves and polarization for both
idealized and hydrodynamical explosion models. We apply the code to a kilonova
model with two distinct ejecta components, one including lanthanide elements
with relatively high opacities and the other devoid of lanthanides and
characterized by lower opacities. We find that a model with total ejecta mass
$M_mathrm{ej}=0.04,M_odot$ and half-opening angle of the lanthanide-rich
component $Phi=30^circ$ provides a good match to GW 170817 / AT 2017gfo for
orientations near the polar axis (i.e. for a system viewed close to face-on).
We then show how crucial is the use of self-consistent multi-dimensional models
in place of combining one-dimensional models to infer important parameters as
the ejecta masses. We finally explore the impact of $M_mathrm{ej}$ and $Phi$
on the synthetic observables and highlight how the relatively fast computation
times of POSSIS make it well-suited to perform parameter-space studies and
extract key properties of supernovae and kilonovae. Spectra calculated with
POSSIS in this and future studies will be made publicly available.

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