Photon and axion oscillation in a magnetized medium: A general treatment

Abstract

Pseudoscalar particles, with almost zero mass and very weak coupling to the visible matter, arise in many extensions of the standard model of particle physics. Their mixing with photons in the presence of an external magnetic field leads to many interesting astrophysical and cosmological consequences. This mixing depends on the medium properties, the momentum of the photon and the background magnetic field. Here we give a general treatment of pseudoscalar-photon oscillations in a background magnetic field, taking the Faraday term into account. We give predictions valid in all regimes, under the assumption that the frequency of the wave is much higher than the plasma frequency of the medium. At sufficiently high frequencies, the Faraday effect is negligible and we reproduce the standard pseudoscalar-photon mixing phenomenon. However at low frequencies, where Faraday effect is important, the mixing formulae are considerably modified. We explicitly compute the contribution due to the longitudinal mode of the photon and show that it is negligible.

Photon-axion mixing within the jets of active galactic nuclei and prospects for detection

“…For the values relevant to this work, Faraday rotation effects can be neglected [34]. When P 0 ≃ 1, photon-ALP conversion is saturated, since for every photon converting into an ALP there is also an ALP converting to a photon.…”

Extragalactic photon-ALP conversion at CTA energies

“…In the present work we take a closer look at the qualitative impact of this contribution on the photon-ALP oscillations in extragalactic magnetic fields. In particular, we expand on the considerable progress in the analytical description of oscillations between photons and ALPs [60,[67][68][69][70][71][72][73][74][75][76][77] by treating absorption and dispersion rigorously. Because the additional contribution suppresses the oscillation length such that l osc ≈ 80 TeV ω Mpc for ω 3 TeV, we also present an interpretation of the various phenomena and issues of photon-ALP oscillations that arise in the regime where l osc becomes of similar size as l and l t .…”

Photon-axion conversion, magnetic field configuration, and polarization of photons

“…Mixing can also increase the transparency of high energy photon [17][18][19][20][21][22][23][24][25][26]. In addition, the astrophysical and cosmological consequences have been studied from various points of view [27][28][29][30]. Conventionally, one assumes that the universe is made by patches of coherent domains, each with a uniform magnetic field and that their direction varies randomly from domain to domain.…”