V-LoTSS: The circularly polarised LOFAR Two-metre Sky Survey

Callingham, J.R.; Shimwell, T.W.; Vedantham, H.K.; Bassa, C.G.; O’Sullivan, S.P.; Yiu, T.W.H.; Bloot, S.; Best, P.N.; Hardcastle, M.J.; Haverkorn, M.; Kavanagh, R.D.; Lamy, L.; Pope, B.J.S.; Röttgering, H.J.A.; Schwarz, D.J.; Tasse, C.; van Weeren, R.J.; White, G.J.; Zarka, P.; Bomans, D.J.; Bonafede, A.; Bonato, M.; Botteon, A.; Bruggen, M.; Chyży, K.T.; Drabent, A.; Emig, K.L.; Gloudemans, A.J.; Gürkan, G.; Hajduk, M.; Hoang, D.N.; Hoeft, M.; Iacobelli, M.; Kadler, M.; Kunert-Bajraszewska, M.; Mingo, B.; Morabito, L.K.; Nair, D.G.; Pérez-Torres, M.; Ray, T.P.; Riseley, C.J.; Rowlinson, A.; Shulevski, A.; Sweijen, F.; Timmerman, R.; Vaccari, M.; Zheng, J.

Abstract

We present the detection of 68 sources from the most sensitive radio survey in circular polarisation conducted to date. We used the second data release of the 144 MHz LOFAR Two-metre Sky Survey to produce circularly polarised maps with a median noise of 140 µJy beam−1 and resolution of 20″ for ≈27% of the northern sky (5634 deg2). The leakage of total intensity into circular polarisation is measured to be ≈0.06%, and our survey is complete at flux densities ≥1 mJy. A detection is considered reliable when the circularly polarised fraction exceeds 1%. We find the population of circularly polarised sources is composed of four distinct classes: stellar systems, pulsars, active galactic nuclei, and sources unidentified in the literature. The stellar systems can be further separated into chromospherically active stars, M dwarfs, and brown dwarfs. Based on the circularly polarised fraction and lack of an optical counterpart, we show it is possible to infer whether the unidentified sources are likely unknown pulsars or brown dwarfs. By the completion of this survey of the northern sky, we expect to detect 300±100 circularly polarised sources.

Citation

Callingham, J., Shimwell, T., Vedantham, H., Bassa, C., O’Sullivan, S., Yiu, T., …Zheng, J. (2023). V-LoTSS: The circularly polarised LOFAR Two-metre Sky Survey. Astronomy & Astrophysics, 670, Article A124. https://doi.org/10.1051/0004-6361/202245567

• Journal Article Type: Article
• Acceptance Date: Dec 17, 2022
• Online Publication Date: Feb 17, 2023
• Publication Date: 2023-02
• Deposit Date: Jun 7, 2023
• Publicly Available Date: Jun 21, 2023
• Journal: Astronomy & Astrophysics
• Print ISSN: 0004-6361
• Electronic ISSN: 1432-0746
• Publisher: EDP Sciences
• Peer Reviewed: Peer Reviewed
• Volume: 670
• Article Number: A124
• DOI: https://doi.org/10.1051/0004-6361/202245567
• Public URL: https://durham-repository.worktribe.com/output/1172631