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Lookup NU author(s): Dr Luiz Felippe RodriguesORCiD, Dr Graeme Sarson, Professor Anvar ShukurovORCiD, Professor Paul BushbyORCiD, Dr Andrew Fletcher
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).
We examine the evolution of the Parker instability in galactic disks using 3D numerical simulations. We consider a local Cartesian box section of a galactic disk, where gas, magnetic fields, and cosmic rays are all initially in a magnetohydrostatic equilibrium. This is done for different choices of initial cosmic-ray density and magnetic field. The growth rates and characteristic scales obtained from the models, as well as their dependences on the density of cosmic rays and magnetic fields, are in broad agreement with previous (linearized, ideal) analytical work. However, this nonideal instability develops a multimodal 3D structure, which cannot be quantitatively predicted from the earlier linearized studies. This 3D signature of the instability will be of importance in interpreting observations. As a preliminary step toward such interpretations, we calculate synthetic polarized intensity and Faraday rotation measure (RM) maps, and the associated structure functions of the latter, from our simulations; these suggest that the correlation scales inferred from RM maps are a possible probe for the cosmic-ray content of a given galaxy. Our calculations highlight the importance of cosmic rays in these measures, making them an essential ingredient of realistic models of the interstellar medium.
Author(s): Rodrigues LFS, Sarson GR, Shukurov A, Bushby PJ, Fletcher A
Publication type: Article
Publication status: Published
Journal: The Astrophysical Journal
Year: 2016
Volume: 816
Issue: 1
Print publication date: 01/01/2016
Online publication date: 21/12/2015
Acceptance date: 05/11/2015
Date deposited: 10/02/2016
ISSN (print): 0004-637X
ISSN (electronic): 1538-4357
Publisher: IOP
URL: http://dx.doi.org/10.3847/0004-637X/816/1/2
DOI: 10.3847/0004-637X/816/1/2
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