The observability of magnetohydrodynamic supernovae and their remnants using MeV gamma lines

Magneto-rotational supernovae (MR-SNe) are rare, highly energetic explosions characterized by exceptionally strong magnetic fields. Although uncommon, they are promising candidates for enriching galaxies with heavy r-process elements. Due to their rapid and early mass ejection compared to typical core-collapse supernovae, MR-SNe can provide the neutron-rich conditions necessary for robust r-process nucleosynthesis. In this work, we simulate beta-decay gamma-ray emission from an MR-SN at various evolutionary stages, from early epochs to optically thin phases, using tracer data from the ejecta in conjunction with the PRISM nucleosynthesis network and the ENDF/B-VIII.0 nuclear database. Our results show that in supernova remnants, gamma-ray signatures of isotopes such as 126Sn (and its daughter 126Sb) would serve as a compelling indicator of an r-process-producing supernova. Furthermore, the neutron-rich environments conducive to the r-process may also enhance the synthesis of 60Fe, making the detection of 60Fe (or its decay product 60Co) an additional diagnostic of favorable conditions. We also present predictions for prompt gamma-ray emissions from a future Galactic MR-SN event and highlight isotopes such as 131I, 132I, 132Te, 125Sb, 106Rh, and 103Ru as promising candidates for detection with upcoming MeV gamma-ray observatories.