Origin of Pulsed Radio Emission from Magnetars

Zeng, Shuzhe; Philippov, Alexander; Juno, James; Beloborodov, Andrei M.; Popova, Elena

doi:10.3847/2041-8213/ae2ade

Origin of Pulsed Radio Emission from Magnetars

Journal Article · Wed Dec 31 00:00:00 EST 2025 · The Astrophysical Journal. Letters

DOI:https://doi.org/10.3847/2041-8213/ae2ade· OSTI ID:3013631

^[1]; ^[1]; ^[2]; ^[3]; Popova, Elena ^[1]

Univ. of Maryland, College Park, MD (United States)
Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)
Columbia Univ., New York, NY (United States); Max Planck Institute for Astrophysics, Garching (Germany)

Extended periods of radio pulsations have been observed for six magnetars, displaying characteristics different from those of ordinary pulsars. In this Letter, we argue that radio emission is generated in a closed, twisted magnetic flux bundle originating near the magnetic pole and extending beyond 100 km from the magnetar. The electron–positron flow in the twisted bundle has to carry electric current and, at the same time, experiences a strong drag from the radiation field of the magnetar. This combination forces the plasma into a “radiatively locked” state with a sustained two-stream instability, generating radio emission. We demonstrate this mechanism using novel first-principles simulations that follow the plasma behavior by solving the relativistic Vlasov equation with the discontinuous Galerkin method. First, using one-dimensional simulations, we demonstrate how radiative drag induces the two-stream instability, sustaining turbulent electric fields. When extended to two dimensions, the system produces electromagnetic waves, including superluminal modes capable of escaping the magnetosphere. We measure their frequency and emitted power and incorporate the local simulation results into a global magnetospheric model. The model explains key features of the observed radio emission from magnetars: its appearance after an X-ray outburst, wide pulse profiles, luminosities ∼10³⁰ erg s⁻¹, and a broad range of frequencies extending up to ∼100 GHz.

View Accepted Manuscript (DOE)

Research Organization:: Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)

Sponsoring Organization:: National Science Foundation (NSF); Simons Foundation; Texas Advanced Computing Center; USDOE Office of Science (SC)

Grant/Contract Number:: AC02-09CH11466

OSTI ID:: 3013631

Journal Information:: The Astrophysical Journal. Letters, Journal Name: The Astrophysical Journal. Letters Journal Issue: 2 Vol. 996; ISSN 2041-8205; ISSN 2041-8213

Publisher:: IOP PublishingCopyright Statement

Country of Publication:: United States

Language:: English

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