Dipole radiation and beyond from axion stars in electromagnetic fields

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dc.citation.articleNumber182
dc.citation.journalTitleJournal of High Energy Physics
dc.citation.volumeNumber2021
dc.contributor.authorAmin, Mustafa A.
dc.contributor.authorLong, Andrew J.
dc.contributor.authorMou, Zong-Gang
dc.contributor.authorSaffin, Paul M.
dc.date.accessioned2022-05-25T17:37:43Z
dc.date.available2022-05-25T17:37:43Z
dc.date.issued2021
dc.description.abstractWe investigate the production of photons from coherently oscillating, spatially localized clumps of axionic fields (oscillons and axion stars) in the presence of external electromagnetic fields. We delineate different qualitative behaviour of the photon luminosity in terms of an effective dimensionless coupling parameter constructed out of the axion-photon coupling, and field amplitude, oscillation frequency and radius of the axion star. For small values of this dimensionless coupling, we provide a general analytic formula for the dipole radiation field and the photon luminosity per solid angle, including a strong dependence on the radius of the configuration. For moderate to large coupling, we report on a non-monotonic behavior of the luminosity with the coupling strength in the presence of external magnetic fields. After an initial rise in luminosity with the coupling strength, we see a suppression (by an order of magnitude or more compared to the dipole radiation approximation) at moderately large coupling. At sufficiently large coupling, we find a transition to a regime of exponential growth of the luminosity due to parametric resonance. We carry out 3+1 dimensional lattice simulations of axion electrodynamics, at small and large coupling, including non-perturbative effects of parametric resonance as well as backreaction effects when necessary. We also discuss medium (plasma) effects that lead to resonant axion to photon conversion, relevance of the coherence of the soliton, and implications of our results in astrophysical and cosmological settings.
dc.identifier.citationAmin, Mustafa A., Long, Andrew J., Mou, Zong-Gang, et al.. "Dipole radiation and beyond from axion stars in electromagnetic fields." <i>Journal of High Energy Physics,</i> 2021, (2021) Springer Nature: https://doi.org/10.1007/JHEP06(2021)182.
dc.identifier.digitalDipoleRadiationAndBeyondFromAx
dc.identifier.doihttps://doi.org/10.1007/JHEP06(2021)182
dc.identifier.urihttps://hdl.handle.net/1911/112415
dc.language.isoeng
dc.publisherSpringer Nature
dc.rightsThis article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/
dc.titleDipole radiation and beyond from axion stars in electromagnetic fields
dc.typeJournal article
dc.type.dcmiText
dc.type.publicationpublisher version
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