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Magnetic Dynamo Caused by Axions in Neutron Stars.
Filippo Anzuini1,2,3, José A Pons4, Antonio Gómez-Bañón4
1School of Physics and Astronomy, Monash University, Clayton, Victoria 3800, Australia.
Physical Review Letters
|March 3, 2023
Summary
Axion-photon coupling can amplify neutron star magnetic fields and internal heating. This contradicts observations, leading to derived bounds on axion properties to prevent dynamo activation.
Area of Science:
- Astrophysics
- Particle Physics
- Condensed Matter Physics
Background:
- Axion-photon coupling modifies electrodynamics, impacting astrophysical objects.
- Neutron stars possess strong magnetic fields and are potential axion laboratories.
Purpose of the Study:
- Investigate the impact of axion-photon coupling on neutron star magnetic fields and thermal properties.
- Derive constraints on axion parameters based on neutron star observations.
Main Methods:
- Theoretical modeling of axion-photon interactions within neutron stars.
- Analysis of Maxwell's equations with an added dynamo term.
- Comparison of theoretical predictions with observational data of thermally emitting neutron stars.
Main Results:
- Axion-photon coupling can drive a magnetic dynamo, significantly increasing neutron star magnetic energy.
- This dynamo mechanism leads to substantial internal heating via enhanced dissipation of electric currents.
- Predicted increases in magnetic energy and thermal luminosity contradict observations of stable neutron stars.
Conclusions:
- The magnetic dynamo mechanism driven by axions is constrained by current neutron star observations.
- New bounds on the axion decay constant and axion mass can be derived to prevent dynamo activation.
- These findings have implications for axion detection strategies and fundamental physics.
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