Speaker
Description
We investigate multi-messenger signatures from QCD-axion ultracompact minihalos seeded by stellar-mass primordial black holes. During the inspiral of a neutron star around the central PBH, dynamical friction from the dense axion minihalo modifies the gravitational-wave phase, while axions entering the neutron-star magnetosphere can resonantly convert into narrow-band radio photons. We model the minihalo formation, adopt a conservative inner density profile together with a phenomenological phase-space distribution. We then calculate the gravitational focusing of axions near the conversion surface and determine the resulting radio and gravitational-wave signals. The combined gravitational-wave and radio observations provide a distinctive probe of both the compact and particle components of dark matter (arXiv: 2608.25338 [hep-ph]).