Probing Isomeric Transitions in Gamma-Ray Bursts from Neutron Star Mergers

Neutron star mergers are rich sources of elements heavier than iron, created through rapid nucleosynthesis processes. The landmark detection of a binary neutron star merger GW170817, was observed through both gravitational waves and electromagnetic signals. This event included a gamma-ray burst (GRB 170817A) shortly after the merger, followed by a prolonged afterglow.

A notable aspect of GRB 170817A was its gamma-ray spectrum, exhibiting two distinct components—a hard short pulse and a softer thermal one. This study investigates the possibility of this GRB spectrum to contain gamma-ray de-excitations from isomeric transitions. We establish a criterion to select isomers that potentially explain the spectral feature of this GRB.

We developed an interactive webpage, showcasing gamma-ray spectra from key isomers. This data will be integrated into astrophysical simulations, aiming to precisely predict isomeric abundances from astrophysical rapid-processes. This research enhances our understanding of nuclear processes in cosmic events and contributes to the broader field of astrophysics.