Wollaeger Abstract: Kilonova Model Grid from Multigroup Radiative Transfer in 2D Axisymmetry

The mass ejected from the merger of two neutron stars undergoes r-process nucleosynthesis, producing heavy elements that radioactively decay.  This decay heats the expanding ejecta and powers a kilonova: an optical-IR transient on the timescale of days to weeks.  On August 17, 2017, neutron star merger GW170817 was observed in the form of gravitational waves and a kilonova, providing a wealth of electromagnetic data and prompting light curve modeling efforts to get estimates of the ejecta properties.  Due to the variability in fidelity and underlying assumptions of the kilonova models, estimates of the dynamical and post-merger (wind) ejecta mass both varied by orders of magnitude, and ejecta speeds by a factor of a few.  To control for the effect of model fidelity, using one code we simulate a suite of kilonova models that span the space of uncertainty of GW170817 ejecta mass and velocity.  The models assume a two-component morphology with toroidal dynamical ejecta and either spherical or lobed wind, and two fiducial wind compositions.  The simulations are performed with SuperNu, a Monte Carlo radiative transfer code, in 2D axisymmetric geometry with multigroup opacity from the LANL suite of relativistic atomic physics codes.  We compare the model light curves and spectra to those of GW170817.  This grid of models is intended for use in constraining uncertainty in future kilonova observations, and augmented or refined as time proceeds.