Issue |
A&A
Volume 686, June 2024
|
|
---|---|---|
Article Number | A104 | |
Number of page(s) | 16 | |
Section | Galactic structure, stellar clusters and populations | |
DOI | https://doi.org/10.1051/0004-6361/202348993 | |
Published online | 03 June 2024 |
The Galactic latitude dependency of Faraday complexity in the S-PASS/ATCA RM catalogue
1
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
e-mail: sranchod@mpifr-bonn.mpg.de
2
Wits Centre for Astrophysics, School of Physics, University of the Witwatersrand, 1 Jan Smuts Avenue, Johannesburg 2000, South Africa
3
Department of Physics, University of Pretoria, Private Bag X20, Pretoria 0028, South Africa
4
SKA Observatory, Jodrell Bank, Lower Withington, Macclesfield SK11 9FT, UK
5
Research School of Astronomy & Astrophysics, Australian National University, Canberra, ACT 2611, Australia
Received:
18
December
2023
Accepted:
14
March
2024
The S-band Polarisation All Sky Survey (SPASS/ATCA) rotation measure (RM) catalogue is the largest broadband RM catalogue to date, increasing the RM density in the sparse southern sky. Through analysis of this catalogue, we report a latitude dependency of the Faraday complexity of polarised sources in this catalogue within 10° of the Galactic plane towards the inner Galaxy. In this study, we aim to investigate this trend with follow-up observations using the Australia Telescope Compact Array (ATCA). We observe 95 polarised sources from the SPASS/ATCA RM catalogue at 1.1–3.1 GHz with ATCA’s 6 km configuration. We present Stokes QU fitting results and a comparative analysis with the SPASS/ATCA catalogue. We find an overall decrease in complexity in these sources with the higher angular resolution observations, with a complexity fraction of 42%, establishing that the majority of the complexity in the SPASS/ATCA sample is due to the mixing-in of diffuse Galactic emission at scales θ > 2.8′. Furthermore, we find a correlation between our observed small-scale complexity θ < 2.8′ and the Galactic spiral arms, which we interpret to be due to Galactic turbulence or small-scale polarised emission. These results emphasise the importance of considering the maximum angular scale to which the observations are sensitive in the classification of Faraday complexity; the effect of which can be more carefully investigated with SKA-precursor and pathfinder arrays (e.g. MeerKAT and ASKAP).
Key words: polarization / techniques: polarimetric / Galaxy: general / radio continuum: galaxies
© The Authors 2024
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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Open access funding provided by Max Planck Society.
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