Issue |
A&A
Volume 622, February 2019
LOFAR Surveys: a new window on the Universe
|
|
---|---|---|
Article Number | A16 | |
Number of page(s) | 12 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361/201833832 | |
Published online | 19 February 2019 |
The intergalactic magnetic field probed by a giant radio galaxy
1 Hamburger Sternwarte, Universität Hamburg, Gojenbergsweg 112, 21029 Hamburg, Germany
e-mail: shane@hs.uni-hamburg.de
2 Astronomical Observatory, Jagiellonian University, ul. Orla 171, Kraków, 30-244, Poland
3 Department of Physics and Astronomy, University of Calgary, Calgary, Alberta, T2N 1N4, Canada
4 CSIRO Astronomy and Space Science, PO Box 1130 Bentley, WA, 6102, Australia
5 The Cosmic Dawn Center, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark
6 Centre for Astrophysics and Cosmology, Science Institute, University of Iceland, Dunhagi 5, 107 Reykjavík, Iceland
7 Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen Ø, Denmark
8 INAF – Osservatorio Astronomico di Cagliari, Via della Scienza 5, 09047 Selargius (CA), Italy
9 Centre for Astrophysics Research, School of Physics, Astronomy and Mathematics, University of Hertfordshire, College Lane, Hatfield, AL10 9AB, UK
10 ASTRON, The Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA Dwingeloo, The Netherlands
11 Leiden Observatory, Leiden University, PO Box 9513 2300 RA Leiden, The Netherlands
12 GEPI & USN, Observatoire de Paris, Université PSL, CNRS, 5 Place Jules Janssen, 92190 Meudon, France
13 Department of Physics & Electronics, Rhodes University, PO Box 94 Grahamstown, 6140, South Africa
14 Dipartimento di Fisica e Astronomia, Universitá di Bologna, Via Gobetti 93/2, 40121 Bologna, Italy
15 Departamento de Astronomía, DCNE, Universidad de Guanajuato, Guanajuato, Mexico
16 HH Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol, BS8 1TL, UK
17 Department of Astrophysics/IMAPP, Radboud University Nijmegen, PO Box 9010 6500 GL Nijmegen, the Netherlands
18 Dept. of Space, Earth and Environment, Chalmers University of Technology, Onsala Space Observatory, 43992 Onsala, Sweden
19 INAF – Istituto di Radioastronomia, via P. Gobetti 101, 40129 Bologna, Italy
20 GFZ German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, Germany
21 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121, Bonn, Germany
22 Department of Physics, Kumamoto University, Kumamoto, 860-8555, Japan
23 Dunlap Institute for Astronomy and Astrophysics University of Toronto, Toronto, ON, M5S 3H4, Canada
24 Astrophysics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford, OX1 3RH, UK
Received:
12
July
2018
Accepted:
9
October
2018
Cosmological simulations predict that an intergalactic magnetic field (IGMF) pervades the large scale structure (LSS) of the Universe. Measuring the IGMF is important to determine its origin (i.e. primordial or otherwise). Using data from the LOFAR Two Metre Sky Survey (LoTSS), we present the Faraday rotation measure (RM) and depolarisation properties of the giant radio galaxy J1235+5317, at a redshift of z = 0.34 and 3.38 Mpc in size. We find a mean RM difference between the lobes of 2.5 ± 0.1 rad m−2, in addition to small scale RM variations of ∼0.1 rad m−2 . From a catalogue of LSS filaments based on optical spectroscopic observations in the local universe, we find an excess of filaments intersecting the line of sight to only one of the lobes. Associating the entire RM difference to these LSS filaments leads to a gas density-weighted IGMF strength of ∼0.3 μG. However, direct comparison with cosmological simulations of the RM contribution from LSS filaments gives a low probability (∼5%) for an RM contribution as large as 2.5 rad m−2, for the case of IGMF strengths of 10–50 nG. It is likely that variations in the RM from the Milky Way (on 11′ scales) contribute significantly to the mean RM difference, and a denser RM grid is required to better constrain this contribution. In general, this work demonstrates the potential of the LOFAR telescope to probe the weak signature of the IGMF. Future studies, with thousands of sources with high accuracy RMs from LoTSS, will enable more stringent constraints on the nature of the IGMF.
Key words: galaxies: active / radio continuum: galaxies / galaxies: magnetic fields / galaxies: jets / techniques: polarimetric / galaxies: clusters: individual: J1235+5317
© ESO 2019
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