Relevance of photon-photon dispersion within the jet for blazar axionlike particle searches

Axionlike particles (ALPs) could mix with photons in the presence of astrophysical magnetic fields. Searching for this effect in gamma-ray observations of blazars has provided some of the strongest constraints on ALP parameter space so far. Previously, photon-photon dispersion of gamma rays off of t...

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Main Authors: Davies, J, Cotter, G, Meyer, M
Format: Journal article
Language:English
Published: American Physical Society 2022
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author Davies, J
Cotter, G
Meyer, M
author_facet Davies, J
Cotter, G
Meyer, M
author_sort Davies, J
collection OXFORD
description Axionlike particles (ALPs) could mix with photons in the presence of astrophysical magnetic fields. Searching for this effect in gamma-ray observations of blazars has provided some of the strongest constraints on ALP parameter space so far. Previously, photon-photon dispersion of gamma rays off of the cosmic microwave background has been shown to be important for these calculations and is universally included in ALP-photon mixing models. Here, we assess the effects of dispersion off of other photon fields within the blazar (produced by the accretion disk, the broad line region, the dust torus, starlight, and the synchrotron field) by modeling the jet and fields of the flat spectrum radio quasar 3C454.3 and propagating ALPs through the model both with and without the full dispersion calculation. We find that the full dispersion calculation can strongly affect the mixing, particularly at energies above 100 GeV—often reducing the ALP-photon conversion probability. This could have implications for future searches planned with, e.g., the Cherenkov Telescope Array, particularly those looking for a reduced opacity of the Universe at the highest energies.
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spelling oxford-uuid:8b920f11-6055-4579-84d6-489325619adc2022-04-29T11:30:54ZRelevance of photon-photon dispersion within the jet for blazar axionlike particle searchesJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:8b920f11-6055-4579-84d6-489325619adcEnglishSymplectic ElementsAmerican Physical Society2022Davies, JCotter, GMeyer, MAxionlike particles (ALPs) could mix with photons in the presence of astrophysical magnetic fields. Searching for this effect in gamma-ray observations of blazars has provided some of the strongest constraints on ALP parameter space so far. Previously, photon-photon dispersion of gamma rays off of the cosmic microwave background has been shown to be important for these calculations and is universally included in ALP-photon mixing models. Here, we assess the effects of dispersion off of other photon fields within the blazar (produced by the accretion disk, the broad line region, the dust torus, starlight, and the synchrotron field) by modeling the jet and fields of the flat spectrum radio quasar 3C454.3 and propagating ALPs through the model both with and without the full dispersion calculation. We find that the full dispersion calculation can strongly affect the mixing, particularly at energies above 100 GeV—often reducing the ALP-photon conversion probability. This could have implications for future searches planned with, e.g., the Cherenkov Telescope Array, particularly those looking for a reduced opacity of the Universe at the highest energies.
spellingShingle Davies, J
Cotter, G
Meyer, M
Relevance of photon-photon dispersion within the jet for blazar axionlike particle searches
title Relevance of photon-photon dispersion within the jet for blazar axionlike particle searches
title_full Relevance of photon-photon dispersion within the jet for blazar axionlike particle searches
title_fullStr Relevance of photon-photon dispersion within the jet for blazar axionlike particle searches
title_full_unstemmed Relevance of photon-photon dispersion within the jet for blazar axionlike particle searches
title_short Relevance of photon-photon dispersion within the jet for blazar axionlike particle searches
title_sort relevance of photon photon dispersion within the jet for blazar axionlike particle searches
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AT cotterg relevanceofphotonphotondispersionwithinthejetforblazaraxionlikeparticlesearches
AT meyerm relevanceofphotonphotondispersionwithinthejetforblazaraxionlikeparticlesearches