Enhanced disruption of axion minihalos by multiple stellar encounters in the Milky Way
Phys. Rev. D 111, 123023 – Published 13 June, 2025
DOI: https://doi.org/10.1103/w9rn-qmbx
Abstract
If QCD axion dark matter formed postinflation, axion miniclusters emerged from isocurvature fluctuations and later merged hierarchically into minihalos. These minihalos, potentially disrupted by stellar encounters in the Milky Way, affect axion detectability. We extend prior analyses by more accurately incorporating multiple stellar encounters and dynamical relaxation timescales, simulating minihalo orbits in the Galactic potential. Our results show stellar interactions are more destructive than previously estimated, reducing minihalo mass retention at the solar system to 30%, compared to earlier estimates of 60%. This enhanced loss arises from cumulative energy injections when relaxation periods between stellar encounters are accounted for. The altered minihalo mass function implies a larger fraction of axion dark matter occupies interminihalo space, potentially increasing the local axion density and improving haloscope detection prospects. This work highlights the significance of detailed modeling of stellar disruptions in shaping the axion dark matter distribution.
Physics Subject Headings (PhySH)
Corrections
3 September, 2025
Correction: A typographical error in the text above Eq. (36) has been fixed. A missing sign in the fourth sentence of the third to last paragraph of Sec. IX has been fixed.
