Details

Autor(en) / Beteiligte

• Thomson, Alec J. M.
• McConnell, David
• Lenc, Emil
• Galvin, Timothy J.
• Rudnick, Lawrence
• Heald, George
• Hale, Catherine L.
• Duchesne, Stefan W.
• Anderson, Craig S.
• Carretti, Ettore
• Federrath, Christoph
• Gaensler, B. M.
• Harvey-Smith, Lisa
• Haverkorn, Marijke
• Hotan, Aidan W.
• Ki Ma, Yik
• Murphy, Tara
• McClure-Griffiths, N. M.
• Moss, Vanessa A.
• O’Sullivan, Shane P.
• Raja, Wasim
• Seta, Amit
• Van Eck, Cameron L.
• West, Jennifer L.
• Whiting, Matthew T.
• Wieringa, Mark H.

Titel

The Rapid ASKAP Continuum Survey III: Spectra and Polarisation In Cutouts of Extragalactic Sources (SPICE-RACS) first data release

Ist Teil von

• Publications of the Astronomical Society of Australia, 2023-08, Vol.40, Article e040

Ort / Verlag

New York, USA: Cambridge University Press

Erscheinungsjahr

2023

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The Australian SKA Pathfinder (ASKAP) radio telescope has carried out a survey of the entire Southern Sky at 887.5 MHz. The wide area, high angular resolution, and broad bandwidth provided by the low-band Rapid ASKAP Continuum Survey (RACS-low) allow the production of a next-generation rotation measure (RM) grid across the entire Southern Sky. Here we introduce this project as Spectral and Polarisation in Cutouts of Extragalactic sources from RACS (SPICE-RACS). In our first data release, we image 30 RACS-low fields in Stokes I, Q, U at 25 $^{\prime\prime}$ angular resolution, across 744–1032 MHz with 1 MHz spectral resolution. Using a bespoke, highly parallelised, software pipeline we are able to rapidly process wide-area spectro-polarimetric ASKAP observations. Notably, we use ‘postage stamp’ cutouts to assess the polarisation properties of 105912 radio components detected in total intensity. We find that our Stokes Q and U images have an rms noise of $\sim$ 80 $\unicode{x03BC}$ Jy PSF $^{-1}$ , and our correction for instrumental polarisation leakage allows us to characterise components with $\gtrsim$ 1% polarisation fraction over most of the field of view. We produce a broadband polarised radio component catalogue that contains 5818 RM measurements over an area of $\sim$ 1300 deg $^{2}$ with an average error in RM of $1.6^{+1.1}_{-1.0}$ rad m $^{-2}$ , and an average linear polarisation fraction $3.4^{+3.0}_{-1.6}$ %. We determine this subset of components using the conditions that the polarised signal-to-noise ratio is $>$ 8, the polarisation fraction is above our estimated polarised leakage, and the Stokes I spectrum has a reliable model. Our catalogue provides an areal density of $4\pm2$ RMs deg $^{-2}$ ; an increase of $\sim$ 4 times over the previous state-of-the-art (Taylor, Stil, Sunstrum 2009, ApJ, 702, 1230). Meaning that, having used just 3% of the RACS-low sky area, we have produced the 3rd largest RM catalogue to date. This catalogue has broad applications for studying astrophysical magnetic fields; notably revealing remarkable structure in the Galactic RM sky. We will explore this Galactic structure in a follow-up paper. We will also apply the techniques described here to produce an all-Southern-sky RM catalogue from RACS observations. Finally, we make our catalogue, spectra, images, and processing pipeline publicly available.