Initial LOFAR observations of epoch of reionization windows II. Diffuse polarized emission in the ELAIS-N1 field
- Creators
- Jelić, V.
- de Bruyn, A. G.
- Mevius, M.
- Abdalla, F. B.
- Asad, K. M. B.
- Bernardi, G.
- Brentjens, M. A.
- Bus, S.
- Chapman, E.
- Ciardi, B.
- Daiboo, S.
- Fernandez, E. R.
- Ghosh, A.
- Harker, G.
- Jensen, H.
- Kazemi, S.
- Koopmans, L. V. E.
- Labropoulos, P.
- Martinez-Rubi, O.
- Mellema, G.
- Offringa, A. R.
- Pandey, V. N.
- Patil, A. H.
- Thomas, R. M.
- Vedantham, H. K.
- Veligatla, V.
- Yatawatta, S.
- Zaroubi, S.
- Alexov, A.
- Anderson, J.
- Avruch, I. M.
- Beck, R.
- Bell, M. E.
- Bentum, M. J.
- Best, P.
- Bonafede, A.
- Bregman, J.
- Breitling, F.
- Broderick, J.
- Brouw, W. N.
- Brüggen, M.
- Butcher, H. R.
- Conway, J. E.
- de Gasperin, F.
- de Geus, E.
- Deller, A.
- Dettmar, R.-J.
- Duscha, S.
- Eislöffel, J.
- Engels, D.
- Falcke, H.
- Fallows, R. A.
- Fender, R.
- Ferrari, C.
- Frieswijk, W.
- Garrett, M. A.
- Griessmeier, Jean-Mathias
- Gunst, A. W.
- Hamaker, J. P.
- Hassall, T. E.
- Haverkorn, M.
- Heald, G.
- Hessels, J. W. T.
- Hoeft, M.
- Hörandel, J.
- Horneffer, A.
- van Der Horst, A.
- Iacobelli, M.
- Juette, E.
- Karastergiou, A.
- Kondratiev, V. I.
- Kramer, M.
- Kuniyoshi, M.
- Kuper, G.
- van Leeuwen, J.
- Maat, P.
- Mann, G.
- Mckay-Bukowski, D.
- Mckean, J. P.
- Munk, H.
- Nelles, A.
- Norden, M. J.
- Paas, H.
- Pandey-Pommier, M.
- Pietka, G.
- Pizzo, R.
- Polatidis, A. G.
- Reich, W.
- Röttgering, H.
- Rowlinson, A.
- Scaife, A. M. M.
- Schwarz, D.
- Serylak, M.
- Smirnov, O.
- Steinmetz, M.
- Stewart, A.
- Tagger, Michel
- Tang, Y.
- Tasse, C.
- ter Veen, S.
- Thoudam, S.
- Toribio, C.
- Vermeulen, R.
- Vocks, C.
- van Weeren, R. J.
- Wijers, R. A. M. J.
- Wijnholds, S. J.
- Wucknitz, O.
- Zarka, P.
- Others:
- Netherlands Institute for Radio Astronomy (ASTRON)
- University College of London [London] (UCL)
- Max Planck Institute for Astrophysics ; Max-Planck-Gesellschaft
- University of Pennsylvania [Philadelphia]
- SRON Netherlands Institute for Space Research (SRON)
- Max-Planck-Institut für Radioastronomie (MPIFR)
- University of Southampton
- University of Edinburgh
- Jacobs University [Bremen]
- Leibniz-Institut für Astrophysik Potsdam (AIP)
- Thüringer Landessternwarte Tautenburg (TLS)
- Radboud University [Nijmegen]
- Joseph Louis LAGRANGE (LAGRANGE) ; Université Nice Sophia Antipolis (1965 - 2019) (UNS) ; COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur ; COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS)
- Leiden Observatory [Leiden] ; Universiteit Leiden [Leiden]
- Unité Scientifique de la Station de Nançay (USN) ; Observatoire des Sciences de l'Univers en région Centre (OSUC) ; Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris ; Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris ; Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris ; Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)
- Laboratoire de Physique et Chimie de l'Environnement et de l'Espace (LPC2E) ; Observatoire des Sciences de l'Univers en région Centre (OSUC) ; Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris ; Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris ; Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Centre National d'Études Spatiales [Paris] (CNES)
- Jodrell Bank Centre for Astrophysics (JBCA) ; University of Manchester [Manchester]
- University of Amsterdam [Amsterdam] (UvA)
- Ruhr-Universität Bochum [Bochum]
- Vrije Universiteit Medical Centre (VUMC) ; Vrije Universiteit Amsterdam [Amsterdam] (VU)
- University of Oulu
- Centre de Recherche Astrophysique de Lyon (CRAL) ; École normale supérieure - Lyon (ENS Lyon)-Université Claude Bernard Lyon 1 (UCBL) ; Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)
- School of Physics and Astronomy [Southampton] ; University of Southampton
- Laboratory for Atmospheric and Space Physics [Boulder] (LASP) ; University of Colorado [Boulder]
- Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA) ; Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris ; Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS)
- Institute for Mathematics, Astrophysics and Particle Physics (IMAPP) ; Radboud University [Nijmegen]
- Astronomical Institute Anton Pannekoek (AI PANNEKOEK) ; University of Amsterdam [Amsterdam] (UvA)
- ANR-09-JCJC-0001,OPALES(2009)
Description
Aims. This study aims to characterise the polarized foreground emission in the ELAIS-N1 field and to address its possible implications for extracting of the cosmological 21 cm signal from the LOw-Frequency ARray – Epoch of Reionization (LOFAR-EoR) data.Methods. We used the high band antennas of LOFAR to image this region and RM-synthesis to unravel structures of polarized emission at high Galactic latitudes.Results. The brightness temperature of the detected Galactic emission is on average ~4 K in polarized intensity and covers the range from –10 to + 13 rad m-2 in Faraday depth. The total polarized intensity and polarization angle show a wide range of morphological features. We have also used the Westerbork Synthesis Radio Telescope (WSRT) at 350 MHz to image the same region. The LOFAR and WSRT images show a similar complex morphology at comparable brightness levels, but their spatial correlation is very low. The fractional polarization at 150 MHz, expressed as a percentage of the total intensity, amounts to ≈1.5%. There is no indication of diffuse emission in total intensity in the interferometric data, in line with results at higher frequenciesConclusions. The wide frequency range, high angular resolution, and high sensitivity make LOFAR an exquisite instrument for studying Galactic polarized emission at a resolution of ~1–2 rad m-2 in Faraday depth. The different polarized patterns observed at 150 MHz and 350 MHz are consistent with different source distributions along the line of sight wring in a variety of Faraday thin regions of emission. The presence of polarized foregrounds is a serious complication for epoch of reionization experiments. To avoid the leakage of polarized emission into total intensity, which can depend on frequency, we need to calibrate the instrumental polarization across the field of view to a small fraction of 1%.
Abstract
International audience
Additional details
- URL
- https://hal-insu.archives-ouvertes.fr/insu-01280138
- URN
- urn:oai:HAL:insu-01280138v1
- Origin repository
- UNICA