Application of a helicity proxy to edge-on galaxies. Issue 4 (29th June 2020)

• Record Type: Journal Article
• Authors: Brandenburg, Axel; Furuya, Ray S
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 496:Issue 4(2020)
• Page Start: 4749
• Page End: 4759
• Publication Date: 2020-06-29
• Subjects: dynamo -- MHD -- polarization -- turbulence -- galaxies: individual: NGC 891 -- galaxies: magnetic fields; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/staa1795
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: We study the prospects of detecting magnetic helicity in galaxies by observing the dust polarization of the edge-on galaxy NGC 891. Our numerical results of mean-field dynamo calculations show that there should be a large-scale component of the rotationally invariant parity-odd B polarization that we predict to be negative in the first and third quadrants, and positive in the second and fourth quadrants. The large-scale parity-even E polarization is predicted to be negative near the axis and positive further away in the outskirts. These properties are shown to be mostly a consequence of the magnetic field being azimuthal and the polarized intensity being maximum at the centre of the galaxy and are not a signature of magnetic helicity.