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The Apertif science verification campaign. Characteristics of polarised radio sources

Adebahr, B. and Berger, A. and Adams, E. A. K. and Hess, K. M. and de Blok, W. J. G. and Dénes, H. and Moss, V. A. and Schulz, R. and van der Hulst, J. M. and Connor, L. and Damstra, S. and Hut, B. and Ivashina, M. V. and Loose, G. M. and Maan, Y. and Mika, A. and Mulder, H. and Norden, M. J. and Oostrum, L. C. and Orrú, E. and Ruiter, M. and Smits, R. and van Cappellen, W. A. and van Leeuwen, J. and Vermaas, N. J. and Vohl, D. and Ziemke, J. (2022) The Apertif science verification campaign. Characteristics of polarised radio sources. Astronomy and Astrophysics, 663 . Art. No. A103. ISSN 0004-6361. doi:10.1051/0004-6361/202243201.

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Context. The characteristics of the polarised radio sky are a key ingredient in constraining evolutionary models of magnetic fields in the Universe and their role in feedback processes. The origin of the polarised emission and the characteristics of the intergalactic medium on the line of sight can be investigated using large samples of polarised sources. Ancillary infrared (IR) and optical data can be used to study the nature of the emitting objects. Aims. We analyse five early science datasets from the APERture Tile in Focus (Apertif) phased array feed system to verify the polarisation capabilities of Apertif in view of future larger data releases. We aim to characterise the source population of the polarised sky in the L-Band using polarised source information in combination with IR and optical data. Methods. We use automatic routines to generate full field-of-view Q- and U-cubes and perform rotation measure (RM)-Synthesis, source finding, and cross-matching with published radio, optical, and IR data to generate polarised source catalogues. All sources were inspected individually by eye for verification of their IR and optical counterparts. Spectral energy distribution (SED)-fitting routines were used to determine photometric redshifts, star-formation rates, and galaxy masses. IR colour information was used to classify sources as active galactic nuclei (AGN) or star-forming-dominated and early- or late-type. Results. We surveyed an area of 56 deg² and detected 1357 polarised source components in 1170 sources. The fraction of polarised sources is 10.57% with a median fractional polarisation of 4.70 ± 0.14%. We confirmed the reliability of the Apertif measurements by comparing them with polarised cross-identified NVSS sources. Average RMs of the individual fields lie within the error of the best Milky Way foreground measurements. All of our polarised sources were found to be dominated by AGN activity in the radio regime with most of them being radio-loud (79%) and of the Fanaroff-Riley (FR)II class (87%). The host galaxies of our polarised source sample are dominated by intermediate disc and star-forming disc galaxies. The contribution of star formation to the radio emission is on the order of a few percent for ≈10% of the polarised sources while for ≈90% it is completely dominated by the AGN. We do not see any change in fractional polarisation for different star-formation rates of the AGN host galaxies. Conclusions. The Apertif system is suitable for large-area high-sensitivity polarised sky surveys. The data products of the polarisation analysis pipeline can be used to investigate the Milky Way magnetic field on projected scales of several arcminutes as well as the origin of the polarised emission in AGN and the properties of their host galaxies.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Adebahr, B.0000-0002-5447-6878
Adams, E. A. K.0000-0002-9798-5111
Hess, K. M.0000-0001-9662-9089
de Blok, W. J. G.0000-0001-8957-4518
Dénes, H.0000-0002-9214-8613
Moss, V. A.0000-0002-3005-9738
van der Hulst, J. M.0000-0002-9316-763X
Connor, L.0000-0002-7587-6352
Ivashina, M. V.0000-0002-6584-1826
Loose, G. M.0000-0003-4721-747X
Maan, Y.0000-0002-0862-6062
Mika, A.0000-0003-0666-2032
Oostrum, L. C.0000-0001-8724-8372
van Cappellen, W. A.0000-0002-3390-2268
van Leeuwen, J.0000-0001-8503-6958
Vohl, D.0000-0003-1779-4532
Alternate Title:The Apertif science verification campaign - Characteristics of polarised radio sources
Additional Information:© ESO 2022. Received: 26 January 2022 Accepted: 13 March 2022. This research made use of Montage. It is funded by the National Science Foundation under Grant Number ACI-1440620, and was previously funded by the National Aeronautics and Space Administration’s Earth Science Technology Office, Computation Technologies Project, under Cooperative Agreement Number NCC5-626 between NASA and the California Institute of Technology. The Montage distribution includes an adaptation of the MOPEX algorithm developed at the Spitzer Science Center. BA and AB acknowledge funding from the German Science Foundation DFG, within the Collaborative Research Center SFB1491 “Cosmic Interacting Matters - From Source to Signal”. EAKA is supported by the WISE research programme, which is financed by the Dutch Research Council (NWO). K.M.H. acknowledges funding from the State Agency for Research of the Spanish Ministry of Science, Innovation and Universities through the “Center of Excellence Severo Ochoa” awarded to the Instituto de Astrofísica de Andalucía (SEV-2017-0709); from grant RTI2018-096228-B-C31 (Ministry of Science, Innovation and Universities/State Agency for Research/European Regional Development Funds, European Union); and from the coordination of the participation in SKA-SPAIN, funded by the Ministry of Science and innovation (MICIN). J.M.vdH. and K.M.H. acknowledge funding from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007-2013)/ERC Grant Agreement No. 291531 (‘HIStoryNU’). J.vL. acknowledges funding from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007–2013)/ERC Grant Agreement no. 617199 (‘ALERT’), and from Vici research programme ‘ARGO’ with project number 639.043.815, financed by the Dutch Research Council (NWO). DV acknowledges support from the Netherlands eScience Center (NLeSC) under grant ASDI.15.406. RS acknowledges funding from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007–2013)/ERC Grant Agreement No. 617199. LCO acknowledges funding from the European Research Council under the European Union’s Seventh Framework Programme (FP/2007–2013)/ERC Grant Agreement No. 617199.
Funding AgencyGrant Number
Deutsche Forschungsgemeinschaft (DFG)SFB 1491
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)UNSPECIFIED
Severo OchoaSEV-2017-0709
Ministerio de Ciencia, Innovación y Universidades (MCIU)RTI2018-096228-B-C31
European Regional Development FundUNSPECIFIED
European Research Council (ERC)291531
European Research Council (ERC)617199
Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO)639.043.815
Netherlands eScience CenterASDI.15.406
European Research Council (ERC)617199
Subject Keywords:methods: data analysis / polarization / surveys / galaxies: active / galaxies: magnetic fields
Record Number:CaltechAUTHORS:20220721-8702000
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Official Citation:The Apertif science verification campaign - Characteristics of polarised radio sources B. Adebahr, A. Berger, E. A. K. Adams, K. M. Hess, W. J. G. de Blok, H. Dénes, V. A. Moss, R. Schulz, J. M. van der Hulst, L. Connor, S. Damstra, B. Hut, M. V. Ivashina, G. M. Loose, Y. Maan, A. Mika, H. Mulder, M. J. Norden, L. C. Oostrum, E. Orrú, M. Ruiter, R. Smits, W. A. van Cappellen, J. van Leeuwen, N. J. Vermaas, D. Voh and J. Ziemke A&A, 663 (2022) A103 DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:115740
Deposited By: George Porter
Deposited On:21 Jul 2022 23:01
Last Modified:21 Jul 2022 23:01

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