Statistical properties of the population of the Galactic centre filaments – II. The spacing between filaments

Date

2022-06-20

Department

Program

Citation of Original Publication

F Yusef-Zadeh, R G Arendt, M Wardle, S Boldyrev, I Heywood, W Cotton, F Camilo, Statistical properties of the population of the Galactic centre filaments – II. The spacing between filaments, Monthly Notices of the Royal Astronomical Society, Volume 515, Issue 2, September 2022, Pages 3059–3093, https://doi.org/10.1093/mnras/stac1696

Rights

This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society © 2022 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.

Subjects

Abstract

We carry out a population study of magnetized radio filaments in the Galactic centre using MeerKAT data by focusing on the spacing between the filaments that are grouped. The morphology of a sample of 43 groupings containing 174 magnetized radio filaments are presented. Many grouped filaments show harp-like, fragmented cometary tail-like, or loop-like structures in contrast to many straight filaments running mainly perpendicular to the Galactic plane. There are many striking examples of a single filament splitting into two prongs at a junction, suggestive of a flow of plasma along the filaments. Spatial variations in spectral index, brightness, bending, and sharpening along the filaments indicate that they are evolving on a 105−6-yr time-scale. The mean spacings between parallel filaments in a given grouping peaks at ∼16 arcsec. We argue by modeling that the filaments in a grouping all lie on the same plane and that the groupings are isotropically oriented in 3D space. One candidate for the origin of filamentation is interaction with an obstacle, which could be a compact radio source, before a filament splits and bends into multiple filaments. In this picture, the obstacle or sets the length scale of the separation between the filaments. Another possibility is synchrotron cooling instability occurring in cometary tails formed as a result of the interaction of cosmic ray driven Galactic centre outflow with obstacles such as stellar winds. In this picture, the mean spacing and the mean width of the filaments are expected to be a fraction of a parsec, consistent with observed spacing.