Abstract
Axions are well-motivated candidates for dark matter. Recently, much interest has focused on the detection of photons produced by the resonant conversion of axion dark matter in neutron star magnetospheres. Various groups have begun to obtain radio data to search for the signal, however, more work is needed to obtain a robust theory prediction for the corresponding radio lines. In this work we derive detailed properties for the signal, obtaining both the line shape and time-dependence. The principal physical effects are from refraction in the plasma as well as from gravitation which together lead to substantial lensing which varies over the pulse period. The time-dependence from the co-rotation of the plasma with the pulsar distorts the frequencies leading to a Doppler broadened signal whose width varies in time. For our predictions, we trace curvilinear rays to the line of sight using the full set of equations from Hamiltonian optics for a dispersive medium in curved spacetime. Thus, for the first time, we describe the detailed shape of the line signal as well as its time dependence, which is more pronounced compared to earlier results. Our prediction of the features of the signal will be essential for this kind of dark matter search.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
M. Dine and W. Fischler, The Not So Harmless Axion, Phys. Lett. B 120 (1983) 137 [INSPIRE].
L.F. Abbott and P. Sikivie, A Cosmological Bound on the Invisible Axion, Phys. Lett. B 120 (1983) 133 [INSPIRE].
J. Preskill, M.B. Wise and F. Wilczek, Cosmology of the Invisible Axion, Phys. Lett. B 120 (1983) 127 [INSPIRE].
A. Arvanitaki, S. Dimopoulos, S. Dubovsky, N. Kaloper and J. March-Russell, String Axiverse, Phys. Rev. D 81 (2010) 123530 [arXiv:0905.4720] [INSPIRE].
P. Svrček and E. Witten, Axions In String Theory, JHEP 06 (2006) 051 [hep-th/0605206] [INSPIRE].
W.-Y. Ai, J.S. Cruz, B. Garbrecht and C. Tamarit, Absence of CP violation in the strong interactions, arXiv:2001.07152 [INSPIRE].
R.D. Peccei and H.R. Quinn, Constraints Imposed by CP Conservation in the Presence of Instantons, Phys. Rev. D 16 (1977) 1791 [INSPIRE].
J.E. Kim, Weak Interaction Singlet and Strong CP Invariance, Phys. Rev. Lett. 43 (1979) 103 [INSPIRE].
M.A. Shifman, A.I. Vainshtein and V.I. Zakharov, Can Confinement Ensure Natural CP Invariance of Strong Interactions?, Nucl. Phys. B 166 (1980) 493 [INSPIRE].
M. Dine, W. Fischler and M. Srednicki, A Simple Solution to the Strong CP Problem with a Harmless Axion, Phys. Lett. B 104 (1981) 199 [INSPIRE].
A.R. Zhitnitsky, On Possible Suppression of the Axion Hadron Interactions (in Russian), Sov. J. Nucl. Phys. 31 (1980) 260 [INSPIRE].
L. Di Luzio, M. Giannotti, E. Nardi and L. Visinelli, The landscape of QCD axion models, Phys. Rept. 870 (2020) 1 [arXiv:2003.01100] [INSPIRE].
G. Sigl, Astrophysical Haloscopes, Phys. Rev. D 96 (2017) 103014 [arXiv:1708.08908] [INSPIRE].
A. Caputo, M. Regis, M. Taoso and S.J. Witte, Detecting the Stimulated Decay of Axions at RadioFrequencies, JCAP 03 (2019) 027 [arXiv:1811.08436] [INSPIRE].
A. Caputo, C.P. Garay and S.J. Witte, Looking for Axion Dark Matter in Dwarf Spheroidals, Phys. Rev. D 98 (2018) 083024 [Erratum ibid. 99 (2019) 089901] [arXiv:1805.08780] [INSPIRE].
R.A. Battye, B. Garbrecht, J.I. McDonald, F. Pace and S. Srinivasan, Dark matter axion detection in the radio/mm-waveband, Phys. Rev. D 102 (2020) 023504 [arXiv:1910.11907] [INSPIRE].
P. Carenza, A. Mirizzi and G. Sigl, Dynamical evolution of axion condensates under stimulated decays into photons, Phys. Rev. D 101 (2020) 103016 [arXiv:1911.07838] [INSPIRE].
R. Balkin, J. Serra, K. Springmann and A. Weiler, The QCD axion at finite density, JHEP 07 (2020) 221 [arXiv:2003.04903] [INSPIRE].
J.H. Buckley, P.S.B. Dev, F. Ferrer and F.P. Huang, Fast radio bursts from axion stars moving through pulsar magnetospheres, Phys. Rev. D 103 (2021) 043015 [arXiv:2004.06486] [INSPIRE].
J.L. Bernal, A. Caputo and M. Kamionkowski, Strategies to Detect Dark-Matter Decays with Line-Intensity Mapping, Phys. Rev. D 103 (2021) 063523 [arXiv:2012.00771] [INSPIRE].
A. Caputo, A. Vittino, N. Fornengo, M. Regis and M. Taoso, Searching for axion-like particle decay in the near-infrared background: an updated analysis, JCAP 05 (2021) 046 [arXiv:2012.09179] [INSPIRE].
J.-F. Fortin, H.-K. Guo, S.P. Harris, D. Kim, K. Sinha and C. Sun, Axions: From magnetars and neutron star mergers to beam dumps and BECs, Int. J. Mod. Phys. D 30 (2021) 2130002 [arXiv:2102.12503] [INSPIRE].
S. Nurmi, E.D. Schiappacasse and T.T. Yanagida, Radio signatures from encounters between neutron stars and QCD-axion minihalos around primordial black holes, JCAP 09 (2021) 004 [arXiv:2102.05680] [INSPIRE].
H. An, F.P. Huang, J. Liu and W. Xue, Radio-frequency Dark Photon Dark Matter across the Sun, Phys. Rev. Lett. 126 (2021) 181102 [arXiv:2010.15836] [INSPIRE].
G.G. Raffelt, Stars as laboratories for fundamental physics: The astrophysics of neutrinos, axions, and other weakly interacting particles (1996) [INSPIRE].
F.V. Day and J.I. McDonald, Axion superradiance in rotating neutron stars, JCAP 10 (2019) 051 [arXiv:1904.08341] [INSPIRE].
C.A.J. O’Hare, A. Caputo, A.J. Millar and E. Vitagliano, Axion helioscopes as solar magnetometers, Phys. Rev. D 102 (2020) 043019 [arXiv:2006.10415] [INSPIRE].
B. Garbrecht and J.I. McDonald, Axion configurations around pulsars, JCAP 07 (2018) 044 [arXiv:1804.04224] [INSPIRE].
A. Prabhu and N.M. Rapidis, Resonant Conversion of Dark Matter Oscillons in Pulsar Magnetospheres, JCAP 10 (2020) 054 [arXiv:2005.03700] [INSPIRE].
T.D.P. Edwards, B.J. Kavanagh, L. Visinelli and C. Weniger, Transient Radio Signatures from Neutron Star Encounters with QCD Axion Miniclusters, arXiv:2011.05378 [INSPIRE].
J.-F. Fortin, H.-K. Guo, S.P. Harris, E. Sheridan and K. Sinha, Magnetars and axion-like particles: probes with the hard X-ray spectrum, JCAP 06 (2021) 036 [arXiv:2101.05302] [INSPIRE].
T.K. Poddar and S. Mohanty, Probing the angle of birefringence due to long range axion hair from pulsars, Phys. Rev. D 102 (2020) 083029 [arXiv:2003.11015] [INSPIRE].
S.P. Harris, J.-F. Fortin, K. Sinha and M.G. Alford, Axions in neutron star mergers, JCAP 07 (2020) 023 [arXiv:2003.09768] [INSPIRE].
M.S. Pshirkov and S.B. Popov, Conversion of Dark matter axions to photons in magnetospheres of neutron stars, J. Exp. Theor. Phys. 108 (2009) 384 [arXiv:0711.1264] [INSPIRE].
D. Lai and J. Heyl, Probing Axions with Radiation from Magnetic Stars, Phys. Rev. D 74 (2006) 123003 [astro-ph/0609775] [INSPIRE].
A. Hook, Y. Kahn, B.R. Safdi and Z. Sun, Radio Signals from Axion Dark Matter Conversion in Neutron Star Magnetospheres, Phys. Rev. Lett. 121 (2018) 241102 [arXiv:1804.03145] [INSPIRE].
F.P. Huang, K. Kadota, T. Sekiguchi and H. Tashiro, Radio telescope search for the resonant conversion of cold dark matter axions from the magnetized astrophysical sources, Phys. Rev. D 97 (2018) 123001 [arXiv:1803.08230] [INSPIRE].
D.A. Camargo, F.S. Queiroz and R. Sturani, Detecting Dark Matter with Neutron Star Spectroscopy, JCAP 09 (2019) 051 [arXiv:1901.05474] [INSPIRE].
B.R. Safdi, Z. Sun and A.Y. Chen, Detecting Axion Dark Matter with Radio Lines from Neutron Star Populations, Phys. Rev. D 99 (2019) 123021 [arXiv:1811.01020] [INSPIRE].
T.D.P. Edwards, M. Chianese, B.J. Kavanagh, S.M. Nissanke and C. Weniger, Unique Multimessenger Signal of QCD Axion Dark Matter, Phys. Rev. Lett. 124 (2020) 161101 [arXiv:1905.04686] [INSPIRE].
M. Leroy, M. Chianese, T.D.P. Edwards and C. Weniger, Radio Signal of Axion-Photon Conversion in Neutron Stars: A Ray Tracing Analysis, Phys. Rev. D 101 (2020) 123003 [arXiv:1912.08815] [INSPIRE].
MADMAX interest Group collaboration, MADMAX: A new road to axion dark matter detection, J. Phys. Conf. Ser. 1342 (2020) 012098 [arXiv:1712.01062] [INSPIRE].
MADMAX collaboration, A new experimental approach to probe QCD axion dark matter in the mass range above 40 μeV, Eur. Phys. J. C 79 (2019) 186 [arXiv:1901.07401] [INSPIRE].
HAYSTAC collaboration, HAYSTAC Status, Results, and Plans, in 13th Conference on the Intersections of Particle and Nuclear Physics, (2019) [arXiv:1901.01668] [INSPIRE].
ADMX collaboration, A SQUID-based microwave cavity search for dark-matter axions, Phys. Rev. Lett. 104 (2010) 041301 [arXiv:0910.5914] [INSPIRE].
B.T. McAllister, G. Flower, E.N. Ivanov, M. Goryachev, J. Bourhill and M.E. Tobar, The ORGAN Experiment: An axion haloscope above 15 GHz, Phys. Dark Univ. 18 (2017) 67 [arXiv:1706.00209] [INSPIRE].
M. Lawson, A.J. Millar, M. Pancaldi, E. Vitagliano and F. Wilczek, Tunable axion plasma haloscopes, Phys. Rev. Lett. 123 (2019) 141802 [arXiv:1904.11872] [INSPIRE].
J. Schütte-Engel et al., Axion quasiparticles for axion dark matter detection, JCAP 08 (2021) 066 [arXiv:2102.05366] [INSPIRE].
M. Baryakhtar, J. Huang and R. Lasenby, Axion and hidden photon dark matter detection with multilayer optical haloscopes, Phys. Rev. D 98 (2018) 035006 [arXiv:1803.11455] [INSPIRE].
J.W. Foster et al., Green Bank and Effelsberg Radio Telescope Searches for Axion Dark Matter Conversion in Neutron Star Magnetospheres, Phys. Rev. Lett. 125 (2020) 171301 [arXiv:2004.00011] [INSPIRE].
J. Darling, New Limits on Axionic Dark Matter from the Magnetar PSR J1745-2900, Astrophys. J. Lett. 900 (2020) L28 [arXiv:2008.11188] [INSPIRE].
J. Darling, Search for Axionic Dark Matter Using the Magnetar PSR J1745-2900, Phys. Rev. Lett. 125 (2020) 121103 [arXiv:2008.01877] [INSPIRE].
S.J. Witte, D. Noordhuis, T.D.P. Edwards and C. Weniger, Axion-Photon Conversion in Neutron Star Magnetospheres: The Role of the Plasma in the Goldreich-Julian Model, arXiv:2104.07670 [INSPIRE].
G. Raffelt and L. Stodolsky, Mixing of the Photon with Low Mass Particles, Phys. Rev. D 37 (1988) 1237 [INSPIRE].
T. Poston and I. Stewart, Catastrophe Theory and Its Applications, Dover books on mathematics, Dover Publications (1996).
M.S. Alenazi and P. Gondolo, Phase-space distribution of unbound dark matter near the Sun, Phys. Rev. D 74 (2006) 083518 [astro-ph/0608390] [INSPIRE].
A. Rogers, Frequency-dependent effects of gravitational lensing within plasma, Mon. Not. Roy. Astron. Soc. 451 (2015) 17 [arXiv:1505.06790] [INSPIRE].
F.H. Vincent et al., Accurate Ray-tracing of Realistic Neutron Star Atmospheres for Constraining Their Parameters, Astrophys. J. 855 (2018) 116 [arXiv:1711.02414] [INSPIRE].
D. Psaltis and T. Johannsen, A Ray-Tracing Algorithm for Spinning Compact Object Spacetimes with Arbitrary Quadrupole Moments. I. Quasi-Kerr Black Holes, Astrophys. J. 745 (2012) 1 [arXiv:1011.4078] [INSPIRE].
T. Johannsen and D. Psaltis, Testing the No-Hair Theorem with Observations in the Electromagnetic Spectrum: II. Black-Hole Images, Astrophys. J. 718 (2010) 446 [arXiv:1005.1931] [INSPIRE].
S. Weinberg, Eikonal method in magnetohydrodynamics, Phys. Rev. 126 (1962) 1899.
J.I. Mcdonald and L.B. Ventura, Bending of light in axion backgrounds, arXiv:2008.12923 [INSPIRE].
J.I. McDonald and L.B. Ventura, Optical properties of dynamical axion backgrounds, Phys. Rev. D 101 (2020) 123503 [arXiv:1911.10221] [INSPIRE].
P. Goldreich and W.H. Julian, Pulsar electrodynamics, Astrophys. J. 157 (1969) 869 [INSPIRE].
J. Pétri, Theory of pulsar magnetosphere and wind, J. Plasma Phys. 82 (2016) 635820502 [arXiv:1608.04895] [INSPIRE].
J. Bicak and P. Hadrava, General-relativistic radiative transfer theory in refractive and dispersive media, Astron. Astrophys. 44 (1975) 389.
Author information
Authors and Affiliations
Corresponding author
Additional information
Publisher’s Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
ArXiv ePrint: 2104.08290
Rights and permissions
Open Access . This 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.
About this article
Cite this article
Battye, R.A., Garbrecht, B., McDonald, J. et al. Radio line properties of axion dark matter conversion in neutron stars. J. High Energ. Phys. 2021, 105 (2021). https://doi.org/10.1007/JHEP09(2021)105
Received:
Revised:
Accepted:
Published:
DOI: https://doi.org/10.1007/JHEP09(2021)105