The intergalactic magnetic field probed by a giant radio galaxy
Review article, 2019
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.
Galaxies: clusters: individual: J1235+5317
Techniques: polarimetric
Galaxies: active
Galaxies: jets
Galaxies: magnetic fields
Radio continuum: galaxies
Author
Shane P. O'Sullivan
University of Hamburg
J. Machalski
Jagiellonian University in Kraków
C.L. Van Eck
University of Calgary
G. Heald
Commonwealth Scientific and Industrial Research Organisation (CSIRO)
M. Brueggen
University of Hamburg
Johan P.U. Fynbo
Niels Bohr Institute
K. E. Heintz
University of Iceland
M. A. Lara-Lopez
Niels Bohr Institute
V. Vacca
Istituto nazionale di astrofisica (INAF)
M. J. Hardcastle
University of Hertfordshire
T. W. Shimwell
Netherlands Institute for Radio Astronomy (ASTRON)
Leiden University
C. Tasse
Rhodes University
Observatoire de Paris-Meudon
F. Vazza
University of Hamburg
Istituto di Radioastronomia
University of Bologna
H. Andernach
Universidad de Guanajuato
M. Birkinshaw
University of Bristol
M. Haverkorn
Radboud University
Cathy Horellou
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
W. L. Williams
University of Hertfordshire
J. J. Harwood
University of Hertfordshire
G. Brunetti
Istituto di Radioastronomia
J. M. Anderson
German Research Centre for Geosciences (GFZ)
S. A. Mao
Max Planck Society
B. Nikiel-Wroczyński
Jagiellonian University in Kraków
K. Takahashi
Kumamoto University
E. Carretti
Istituto di Radioastronomia
T. Vernstrom
University of Toronto
R. van Weeren
Leiden University
E. Orrú
Netherlands Institute for Radio Astronomy (ASTRON)
L. Morabito
University of Oxford
J. R. Callingham
Netherlands Institute for Radio Astronomy (ASTRON)
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 622 A16Subject Categories
Astronomy, Astrophysics and Cosmology
Other Physics Topics
DOI
10.1051/0004-6361/201833832