The Galactic latitude dependency of Faraday complexity in the S-PASS/ATCA RM catalogue

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...

Full description

Saved in:
Bibliographic Details
Published in:Astronomy and astrophysics (Berlin) 2024-06, Vol.686
Main Authors: Ranchod, S., Mao, S. A., Deane, R., Sridhar, S., Damas-Segovia, A., Livingston, J.D., Ma, Y.K.
Format: Article
Language:English
Subjects:
Angular resolution
Arrays
Broadband
Complexity
Emission
Galactic structure
Sky surveys (astronomy)
Southern sky
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary: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 $ > 2.8'$. Furthermore, we find a correlation between our observed small-scale complexity $ < 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).
ISSN:0004-6361
1432-0746
DOI:10.1051/0004-6361/202348993