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Effective field theory of force-free electrodynamics

Gralla, Samuel E.; Iqbal, Nabil

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Samuel E. Gralla


Force-free electrodynamics (FFE) is a closed set of equations for the electromagnetic field of a magnetically dominated plasma. There are strong arguments for the existence of force-free plasmas near pulsars and active black holes, but FFE alone cannot account for the observational signatures, such as coherent radio emission and relativistic jets and winds. We reformulate FFE as the effective field theory of a cold string fluid and initiate a systematic study of corrections in a derivative expansion. At leading order the effective theory is equivalent to (generalized) FFE, with the strings comprised by magnetic field line world sheets. Higher-order corrections generically give rise to nonzero accelerating electric fields (E⋅B≠0). We discuss potential observable consequences and comment on an intriguing numerical coincidence.


Gralla, S. E., & Iqbal, N. (2019). Effective field theory of force-free electrodynamics. Physical Review D, 99(10), Article 105004.

Journal Article Type Article
Acceptance Date Mar 27, 2019
Online Publication Date May 14, 2019
Publication Date Apr 30, 2019
Deposit Date May 15, 2019
Publicly Available Date May 17, 2019
Journal Physical Review D
Print ISSN 2470-0010
Electronic ISSN 2470-0029
Publisher American Physical Society
Peer Reviewed Peer Reviewed
Volume 99
Issue 10
Article Number 105004
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Published Journal Article (295 Kb)

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Copyright Statement
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by SCOAP3.

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