March 2026 WG3 meeting

Wednesday 18 Mar 2026, 16:00 → 17:00 Europe/Rome

Maurizio Giannotti

Garv Chauhan will present the talk:

Title : 511 keV Gamma-Ray Echo from Particle Decays in Supernovae

Abstract : A core-collapse supernova (CCSN) can lead to the production of beyond Standard Model (BSM) particles such as axion-like particles (ALPs). In my talk, I will discuss how the decays of such heavy species can give rise to a unique 511 keV gamma-ray signature associated with BSM particles produced in the core. We use this signal to set bounds on the $G_{a\gamma\gamma}$ based on measurements from the Pioneer Venus Orbiter during SN 1987A. Moreover, I will show that upcoming MeV-gap gamma-ray telescopes such as COSI and AMEGO with sensitivity in the 511 keV range, can place strong constraints or provide a complementary pathway for ALP discovery. Finally, I will emphasize that such an “echo” signal should exist for all species that decay into neutrinos, radiatively, or directly into positrons.