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Main Authors: Long, Andrew J., Schiappacasse, Enrico D.
Format: Preprint
Published: 2024
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Online Access:https://arxiv.org/abs/2408.04551
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author Long, Andrew J.
Schiappacasse, Enrico D.
author_facet Long, Andrew J.
Schiappacasse, Enrico D.
contents In the strong magnetic field of a neutron star's magnetosphere, axions coupled to electromagnetism develop a nonzero probability to convert into photons. Past studies have revealed that the axion-photon conversion can be resonantly enhanced. We recognize that the axion-photon resonance admits two parametrically distinct resonant solutions, which we call the mass-matched resonance and the Euler-Heisenberg assisted resonance. The mass-matched resonance occurs at a point in the magnetosphere where the radially-varying plasma frequency crosses the axion mass $ω_\mathrm{pl} \approx m_a$. The Euler-Heisenberg assisted resonance occurs where the axion energy satisfies $ω\approx (2 ω_\mathrm{pl}^2 / 7 g_{γγγγ} \bar{B}^2 )^{1/2}$. This second resonance is made possible though the strong background magnetic field $\bar{B}$ as well as the nonzero Euler-Heisenberg four-photon self interaction, which has the coupling $g_{γγγγ} = 8 α^2 / 45 m_e^4$. We study the resonant conversion of relativistic axion dark radiation into photons via the Euler-Heisenberg assisted resonance, and we calculate the expected electromagnetic radiation assuming different values for the axion-photon coupling $g_{aγγ}$ and different amplitudes for the axion flux onto the neutron star $Φ_a$. We briefly discuss several possible sources of axion dark radiation. Achieving a sufficiently strong axion flux to induce a detectable electromagnetic signal seems unlikely.
format Preprint
id arxiv_https___arxiv_org_abs_2408_04551
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Resonant conversion of axion dark radiation into terahertz electromagnetic radiation in a neutron star magnetosphere
Long, Andrew J.
Schiappacasse, Enrico D.
High Energy Physics - Phenomenology
Cosmology and Nongalactic Astrophysics
In the strong magnetic field of a neutron star's magnetosphere, axions coupled to electromagnetism develop a nonzero probability to convert into photons. Past studies have revealed that the axion-photon conversion can be resonantly enhanced. We recognize that the axion-photon resonance admits two parametrically distinct resonant solutions, which we call the mass-matched resonance and the Euler-Heisenberg assisted resonance. The mass-matched resonance occurs at a point in the magnetosphere where the radially-varying plasma frequency crosses the axion mass $ω_\mathrm{pl} \approx m_a$. The Euler-Heisenberg assisted resonance occurs where the axion energy satisfies $ω\approx (2 ω_\mathrm{pl}^2 / 7 g_{γγγγ} \bar{B}^2 )^{1/2}$. This second resonance is made possible though the strong background magnetic field $\bar{B}$ as well as the nonzero Euler-Heisenberg four-photon self interaction, which has the coupling $g_{γγγγ} = 8 α^2 / 45 m_e^4$. We study the resonant conversion of relativistic axion dark radiation into photons via the Euler-Heisenberg assisted resonance, and we calculate the expected electromagnetic radiation assuming different values for the axion-photon coupling $g_{aγγ}$ and different amplitudes for the axion flux onto the neutron star $Φ_a$. We briefly discuss several possible sources of axion dark radiation. Achieving a sufficiently strong axion flux to induce a detectable electromagnetic signal seems unlikely.
title Resonant conversion of axion dark radiation into terahertz electromagnetic radiation in a neutron star magnetosphere
topic High Energy Physics - Phenomenology
Cosmology and Nongalactic Astrophysics
url https://arxiv.org/abs/2408.04551