On the gamma-ray emission of Type Ia Supernovae

TL;DR

This study uses multi-dimensional Monte Carlo simulations to assess how gamma-ray observations can reveal geometric and physical details of Type Ia supernovae, highlighting the importance of viewing angles and the need for more sensitive instruments.

Contribution

It demonstrates that gamma-ray spectra are sensitive to supernova geometry and viewing angle, challenging the reliance on one-dimensional models for interpreting gamma-ray data.

Findings

Moderate asphericity affects gamma-ray spectra significantly.

Viewing-angle effects can mimic parameter variations in models.

Current gamma-ray sensitivity limits constrain useful data collection.

Abstract

A multi-dimension, time-dependent Monte Carlo code is used to compute sample gamma-ray spectra to explore whether unambiguous constraints could be obtained from gamma-ray observations of Type Ia supernovae. Both spherical and aspherical geometries are considered and it is shown that moderate departures from sphericity can produce viewing-angle effects that are at least as significant as those caused by the variation of key parameters in one-dimensional models. Thus gamma-ray data could in principle carry some geometrical information, and caution should be applied when discussing the value of gamma-ray data based only on one-dimensional explosion models. In light of the limited sensitivity of current gamma-ray observatories, the computed theoretical spectra are studied to revisit the issue of whether useful constraints could be obtained for moderately nearby objects. The most useful gamma-ray measurements are likely to be of the light curve and time-dependent hardness ratios, but sensitivity higher than currently available, particularly at relatively hard energies (~2-3 MeV), is desirable.