The intergalactic magnetic field probed by a giant radio galaxy
Reviewartikel, 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: jets

Galaxies: active

Galaxies: clusters: individual: J1235+5317

Techniques: polarimetric

Radio continuum: galaxies

Galaxies: magnetic fields


Shane P. O'Sullivan

Universität Hamburg

J. Machalski

Uniwersytet Jagiellonski w Krakowie

C.L. Van Eck

University of Calgary

G. Heald

CSIRO Astronomy and Space Science

M. Brueggen

Universität Hamburg

Johan P.U. Fynbo

Niels Bohr Institute

K. E. Heintz

Háskóli Íslands

M. A. Lara-Lopez

Niels Bohr Institute

V. Vacca

Osservatorio Astronomico di Cagliari

M. J. Hardcastle

University of Hertfordshire

T. W. Shimwell

Universiteit Leiden

Netherlands Institute for Radio Astronomy (ASTRON)

C. Tasse

GEPI - Galaxies, Etoiles, Physique, Instrumentation

Rhodes University

F. Vazza

Universita di Bologna

Universität Hamburg

Istituto di Radioastronomia

H. Andernach

Universidad de Guanajuato

M. Birkinshaw

University of Bristol

M. Haverkorn

Radboud Universiteit

Cathy Horellou

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik, Extragalaktisk astrofysik

W. L. Williams

University of Hertfordshire

J. J. Harwood

University of Hertfordshire

G. Brunetti

Istituto di Radioastronomia

J. M. Anderson

Deutsches GeoForschungsZentrum (GFZ)

S. A. Mao

Max Planck-institutet

B. Nikiel-Wroczyński

Uniwersytet Jagiellonski w Krakowie

K. Takahashi

Kumamoto University

E. Carretti

Istituto di Radioastronomia

T. Vernstrom

University of Toronto

R. van Weeren

Universiteit Leiden

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


Astronomi, astrofysik och kosmologi

Annan fysik



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