Stimulated capture of axion dark matter around primordial black holes
Abstract
We study the stimulated capture of axion and axion-like particles around primordial black holes, mediated by quartic self-interactions. We identify the parametric regions where Bose-enhanced growth overcomes cosmological dilution and derive analytic criteria for efficient formation and long-term survival of the hydrogenic ground-state cloud, confronting them with current bounds on axion-photon couplings. We discuss observational implications of these PBH+cloud systems, including resonant axion-to-photon conversion in neutron star magnetospheres and finite-size microlensing distortions. In the former case, the resonance condition selects a conversion shell outside the neutron star surface, and we show that the large axion occupation number of the cloud can compensate for the small conversion probability. The resulting transient line flux densities can exceed nominal VLA and ALMA sensitivities in regions where the Galactic encounter rate is observationally relevant. Independently, when the cloud size becomes comparable to or larger than the Einstein radius, finite-size effects can modify the standard point-lens microlensing light curve.
Related
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- Implications of Inelastic Dark Matter for Primordial Dark-Star Evolution: Kinematic Thresholds and Nonthermal Capture
- Coherent versus incoherent amplification: from parametric resonance to the kinetic regime in stimulated axion decay
- Primordial black holes and gravitational waves from aligned axion inflation
- Primordial Black Hole and Gravitational Wave by Peaked Cosmic Perturbations from Axion Curvaton
BibTeX
@misc{branco2026stimulated,
title = {{Stimulated capture of axion dark matter around primordial black holes}},
author = {Nuno P. Branco and João G. Rosa},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.21951},
eprint = {2610.21951},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.21951},
}
RIS
TY - UNPB
TI - Stimulated capture of axion dark matter around primordial black holes
AU - Nuno P. Branco
AU - João G. Rosa
PY - 2026
DA - 2026/10/15
PB - arXiv
DO - 10.48550/arxiv.2610.21951
UR - https://arxiv.org/abs/2610.21951
AB - We study the stimulated capture of axion and axion-like particles around primordial black holes, mediated by quartic self-interactions. We identify the parametric regions where Bose-enhanced growth overcomes cosmological dilution and derive analytic criteria for efficient formation and long-term survival of the hydrogenic ground-state cloud, confronting them with current bounds on axion-photon couplings. We discuss observational implications of these PBH+cloud systems, including resonant axion-to-photon conversion in neutron star magnetospheres and finite-size microlensing distortions. In the former case, the resonance condition selects a conversion shell outside the neutron star surface, and we show that the large axion occupation number of the cloud can compensate for the small conversion probability. The resulting transient line flux densities can exceed nominal VLA and ALMA sensitivities in regions where the Galactic encounter rate is observationally relevant. Independently, when the cloud size becomes comparable to or larger than the Einstein radius, finite-size effects can modify the standard point-lens microlensing light curve.
ER -