Speaker
Description
Dark matter (DM) may accumulate in the gravitational potential of compact astrophysical objects, forming dense bound halos. In particular, if primordial black holes (PBHs) are present, their gravitational field can capture surrounding DM particles and produce a steep density spike in the inner halo region. The resulting compact DM structure provides an environment where microscopic particle processes can lead to macroscopic electromagnetic phenomena.
For axion or axion-like particle (ALP) dark matter, the large phase-space density in the spike can trigger efficient photon production through stimulated decay. Above a critical density, this process may lead to rapid amplification of low-frequency electromagnetic radiation. Such emission is expected to originate from the innermost region of the PBH-induced halo and could contribute to transient or persistent radio signals.
We discuss the formation and evolution of axion halos around PBHs and explore the resulting observational signatures. Photons generated in the DM halo can propagate over cosmological distances and may be detectable by current or future radio observations.