Stabilizing effect of magnetic helicity on magnetic cavities in the intergalactic medium

Candelaresi, S. and Del Sordo, F. (2020) Stabilizing effect of magnetic helicity on magnetic cavities in the intergalactic medium. Astrophysical Journal, 896(1), 86. (doi: 10.3847/1538-4357/ab8dc0)

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We investigate the effect of magnetic helicity on the stability of buoyant magnetic cavities as found in the intergalactic medium. In these cavities we insert helical magnetic fields and test whether or not helicity can increase their stability to shredding through the Kelvin–Helmholtz instability and, with that, their lifetime. This is compared to the case of an external vertical magnetic field that is known to reduce the growth rate of the Kelvin–Helmholtz instability. By comparing a low-helicity configuration with a high-helicity one with the same magnetic energy, we find that an internal helical magnetic field stabilizes the cavity. This effect increases as we increase the helicity content. Stabilizing the cavity with an external magnetic field requires instead a significantly stronger field at higher magnetic energy. We conclude that the presence of helical magnetic fields is a viable mechanism to explain the stability of intergalactic cavities on timescales longer than 100 Myr.

Item Type:Articles
Additional Information:The authors appreciate the support given by the HPC3 Europe program HPC-EUROPA3 (INFRAIA-2016-1-730897). S.C. acknowledges financial support from the UK’s STFC (grant number ST/K000993).
Glasgow Author(s) Enlighten ID:Candelaresi, Dr Simon
Authors: Candelaresi, S., and Del Sordo, F.
College/School:College of Science and Engineering > School of Mathematics and Statistics > Mathematics
Journal Name:Astrophysical Journal
Publisher:IOP Publishing
ISSN (Online):1538-4357
Published Online:16 June 2020
Copyright Holders:Copyright © 2020 The Authors
First Published:First published in Astrophysical Journal 896(1): 86
Publisher Policy:Reproduced under a Creative Commons License

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