Axion dark matter can resonantly convert to photons in the magnetosphere of neutron stars, possibly giving rise to radio signals observable on Earth. This method for the indirect detection of axion dark matter has recently received significant attention in the literature. The calculation of the radio signal is complicated by a number of effects; most importantly, the gravitational infall of the axions onto the neutron star accelerates them to semi-relativistic speed, and the neutron star magnetosphere is highly anisotropic. Both of these factors complicate the calculation of the conversion of axions to photons. In this work, we present the first fully three-dimensional calculation of the axion-photon conversion in highly magnetised anisotropic media. Depending on the axion trajectory, this calculation leads to orders-of-magnitude differences in the conversion compared to the simplified one-dimensional calculation used so far in the literature, altering the directionality of the produced photons. Our results will have important implications for the radio signal one would observe in a telescope.
Millar, Alexander J., et al. "Axion-photon conversion in strongly magnetised plasmas." Journal of Cosmology and Astroparticle Physics, vol. 2021, no. 11, Nov. 2021. https://doi.org/10.1088/1475-7516/2021/11/013
@article{osti_1982456,
author = {Millar, Alexander J. and Baum, Sebastian and Lawson, Matthew and Marsh, M.C. David},
title = {Axion-photon conversion in strongly magnetised plasmas},
annote = {Axion dark matter can resonantly convert to photons in the magnetosphere of neutron stars, possibly giving rise to radio signals observable on Earth. This method for the indirect detection of axion dark matter has recently received significant attention in the literature. The calculation of the radio signal is complicated by a number of effects; most importantly, the gravitational infall of the axions onto the neutron star accelerates them to semi-relativistic speed, and the neutron star magnetosphere is highly anisotropic. Both of these factors complicate the calculation of the conversion of axions to photons. In this work, we present the first fully three-dimensional calculation of the axion-photon conversion in highly magnetised anisotropic media. Depending on the axion trajectory, this calculation leads to orders-of-magnitude differences in the conversion compared to the simplified one-dimensional calculation used so far in the literature, altering the directionality of the produced photons. Our results will have important implications for the radio signal one would observe in a telescope.},
doi = {10.1088/1475-7516/2021/11/013},
url = {https://www.osti.gov/biblio/1982456},
journal = {Journal of Cosmology and Astroparticle Physics},
issn = {ISSN 1475-7516},
number = {11},
volume = {2021},
place = {United States},
publisher = {Institute of Physics (IOP)},
year = {2021},
month = {11}}
USDOE Office of Science (SC), High Energy Physics (HEP); European Research Council (ERC); Swedish Research Council (VR); Swedish Science Council; National Science Foundation (NSF); Gordon and Betty Moore Foundation; Simons Investigator Award
OSTI ID:
1982456
Journal Information:
Journal of Cosmology and Astroparticle Physics, Journal Name: Journal of Cosmology and Astroparticle Physics Journal Issue: 11 Vol. 2021; ISSN 1475-7516