Fundamental physics from the strong-field regime of gravity
Josu Aurrekoetxea - University of Oxford
Mahlmann, J. (2023). Magnetar Eruptions and Electromagnetic Fireworks. Perimeter Institute. https://pirsa.org/23040134
Mahlmann, Jens. Magnetar Eruptions and Electromagnetic Fireworks. Perimeter Institute, Apr. 20, 2023, https://pirsa.org/23040134
@misc{ pirsa_PIRSA:23040134,
doi = {10.48660/23040134},
url = {https://pirsa.org/23040134},
author = {Mahlmann, Jens},
keywords = {Strong Gravity},
language = {en},
title = {Magnetar Eruptions and Electromagnetic Fireworks},
publisher = {Perimeter Institute},
year = {2023},
month = {apr},
note = {PIRSA:23040134 see, \url{https://pirsa.org}}
}
Highly magnetized neutron stars are a source of extreme transients observed in different bands, like the fast radio burst (FRB) and associated hard X-ray burst from the Galactic magnetar SGR 1935+2154. The origin of such outbursts, hard X-rays on the one hand and millisecond duration FRBs on the other hand, is still unknown. We present a global model for various kinds of such magnetar outbursting activities. Crustal surface motions are expected to twist the inner magnetar magnetosphere by shifting the frozen-in footpoints of magnetic field lines. We discuss criteria for the development of various instabilities of 3D twisted flux bundles in the force-free dipolar magnetospheres and compare their energetic properties to observations of magnetar X-ray flares. We then review a recently developed FRB generation mechanism in the outer magnetosphere of a magnetar. The strong magnetic pulse induced by a magnetar flare collides with the current sheet of the magnetar wind, compresses and fragments it into a self-similar chain of magnetic islands. Time-dependent plasma currents created during their collisions produce relatively narrow-band GHz emission with luminosities sufficient to explain bright extragalactic FRBs.
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