A1 Journal article (refereed)
Radio signatures from encounters between neutron stars and QCD-axion minihalos around primordial black holes (2021)
Nurmi, S., Schiappacasse, E. D., & Yanagida, T. T. (2021). Radio signatures from encounters between neutron stars and QCD-axion minihalos around primordial black holes. Journal of Cosmology and Astroparticle Physics, 2021(9), Article 004. https://doi.org/10.1088/1475-7516/2021/09/004
JYU authors or editors
Publication details
All authors or editors: Nurmi, Sami; Schiappacasse, Enrico D.; Yanagida, Tsutomu T.
Journal or series: Journal of Cosmology and Astroparticle Physics
eISSN: 1475-7516
Publication year: 2021
Publication date: 01/09/2021
Volume: 2021
Issue number: 9
Article number: 004
Publisher: IOP Publishing
Publication country: United Kingdom
Publication language: English
DOI: https://doi.org/10.1088/1475-7516/2021/09/004
Publication open access: Not open
Publication channel open access:
Publication is parallel published (JYX): https://jyx.jyu.fi/handle/123456789/78326
Publication is parallel published: https://arxiv.org/abs/2102.05680
Abstract
Probing the QCD axion dark matter (DM) hypothesis is extremely challenging as the axion interacts very weakly with Standard Model particles. We propose a new avenue to test the QCD axion DM via transient radio signatures coming from encounters between neutron stars (NSs) and axion minihalos around primordial black holes (PBHs). We consider a general QCD axion scenario in which the PQ symmetry breaking occurs before (or during) inflation coexisting with a small fraction of DM in the form of PBHs. The PBHs will unavoidably acquire around them axion minihalos with the typical length scale of parsecs. The axion density in the minihalos may be much higher than the local DM density, and the presence of these compact objects in the Milky Way today provides a novel chance for testing the axion DM hypothesis. We study the evolution of the minihalo mass distribution in the Galaxy accounting for tidal forces and estimate the encounter rate between NSs and the dressed PBHs. We find that the encounters give rise to transient line-like emission of radio frequency photons produced by the resonant axion-photon conversion in the NS magnetosphere and the characteristic signal could be detectable with the sensitivity of current and prospective radio telescopes. It would be important to investigate in detail search strategies for such signals which would provide a novel pathway for QCD axion detection.
Keywords: cosmology; dark matter; radio waves; neutron stars; black holes
Contributing organizations
Ministry reporting: Yes
Reporting Year: 2021
JUFO rating: 1