Examining Neutrino-Matter Interactions in the Cassiopeia A Supernova

TL;DR

This study proposes using X-ray observations of Cassiopeia A to confirm neutrino-matter interactions in supernovae by analyzing elemental ratios, providing potential constraints on neutrino properties.

Contribution

It introduces a novel observational method to verify neutrino interactions in supernova remnants through elemental composition analysis.

Findings

Measured Mn/Fe ratio supports neutrino interactions.

Results suggest neutrino processes significantly influence supernova nucleosynthesis.

Method can constrain supernova neutrino parameters.

Abstract

Neutrino interactions with stellar material are widely believed to be fundamental to the explosion of massive stars. However, this important process has remained difficult to confirm observationally. We propose a new method to verify it using X-ray observations of the supernova remnant Cassiopeia A. The elemental composition in its Fe-rich ejecta that could have been produced at the innermost region of the supernova, where neutrinos are expected to interact, allows us to examine the presence of neutrino interactions. Here we demonstrate that the amount of Mn produced without neutrino nucleosynthesis processes (i.e., the $\nu$- and $\nu$p-process) is too small to explain the Mn/Fe mass ratio we measure (0.14--0.67\%). This result supports the operation of significant neutrino interactions in the Cassiopeia A supernova. If the observed Mn/Fe mass ratio purely reflects the production at the innermost region of the supernova, this would be the first robust confirmation of neutrino-matter interactions in an individual supernova. We further show that the Mn/Fe mass ratio has the potential to constrain supernova neutrino parameters (i.e., total neutrino luminosity, neutrino temperature). Future spatially-resolved, high-resolution X-ray spectroscopy will allow us to investigate the details of neutrino-supernova astrophysics through its signatures in elemental composition not only in Cassiopeia A but also in other remnants.