Speaker
Description
Core-collapse supernovae can produce light, weakly interacting particles with MeV-scale masses, such as light dark matter or axion-like particles. After escaping the supernova core with semi-relativistic velocities, these particles propagate through the Galaxy and may reach Earth long after the explosion. Since they propagate with a spread in velocities, the particles from a single supernova arrive as a highly extended packet that can span thousands of years.
It is often assumed that the superposition of packets from many past Galactic supernovae results in a smooth and stationary diffuse flux that can be searched for in terrestrial detectors. In this work, we revisit this approximation and analyze it critically, emphasizing two ingredients that are typically neglected: the finite observation time of detectors and the energy-dependent time structure of the particle packet emitted by each supernova. Considering realistic experimental timescales, detectors effectively probe only a narrow energy slice of each packet, rather than the full spectrum.
Motivated by these effects, we develop a stochastic description of the diffuse flux by simulating the supernova history of our galaxy and computing the resulting distribution of detectable signals. We show that they exhibit sizeable fluctuations in the spectral shape, reflecting the stochastic nature of the SN population. In contrast, the commonly used diffuse approximation effectively averages over these fluctuations and tends to systematically overestimate the expected flux in detectors. Our framework provides a more realistic prediction of the signal and its variability, and naturally allows us to explore the low-mass regime in a consistent way. As an application, we revisit constraints on MeV-scale fermionic dark matter and axion-like particles, obtaining revised bounds based on this stochastic treatment.
This talk is based on https://arxiv.org/pdf/2602.17597
| Main Contribution topic | Light Dark Matter |
|---|---|
| Secondary contribution topic | Axion / Sterile |