The Galactic latitude dependency of Faraday complexity in the S-PASS/ATCA RM catalogue
| Autor: | Ranchod, S., Mao, S. A., Deane, R., Sridhar, S. S., Damas-Segovia, A., Livingston, J. D., Ma, Y. K. |
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| Rok vydání: | 2024 |
| Předmět: | |
| Zdroj: | A&A 686, A104 (2024) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1051/0004-6361/202348993 |
| Popis: | 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$^\circ$ 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 $\theta > 2.8'$. Furthermore, we find a correlation between our observed small-scale complexity $\theta < 2.8'$ 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). Comment: 16 pages, 16 figures |
| Databáze: | arXiv |
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