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.

Radio continuum: galaxies

Galaxies: active

Galaxies: jets

Galaxies: clusters: individual: J1235+5317

Galaxies: magnetic fields

Techniques: polarimetric


Shane P. O'Sullivan

University of Hamburg

J. Machalski

Jagiellonian University in Kraków

C.L. Van Eck

University of Calgary

G. Heald

CSIRO Astronomy and Space Science

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

INAF Osservatorio Astronomico di Cagliari

M. J. Hardcastle

University of Hertfordshire

T. W. Shimwell

Leiden University

Netherlands Institute for Radio Astronomy (ASTRON)

C. Tasse

Rhodes University

Observatoire de Paris-Meudon

F. Vazza

University of Bologna

Istituto di Radioastronomia

University of Hamburg

H. Andernach

Universidad de Guanajuato

M. Birkinshaw

University of Bristol

M. Haverkorn

Radboud University

Cathy Horellou

Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics, Extragalactic Astrophysics

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 A16

Subject Categories

Astronomy, Astrophysics and Cosmology

Other Physics Topics



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