The LOFAR view of intergalactic magnetic fields with giant radio galaxies

Abstract

Giant radio galaxies (GRGs) are physically large radio sources that extend well beyond their host galaxy environment. Their polarization properties are affected by the poorly constrained magnetic field that permeates the intergalactic medium on Mpc scales. A low frequency ($<$ 200 MHz) polarization study of this class of radio sources is now possible with LOFAR. Here we investigate the polarization properties and Faraday rotation measure (RM) of a catalog of GRGs detected in the LoTSS. This is the first low-frequency polarization study of a large sample of radio galaxies selected on their physical size. We explore the magneto-ionic properties of their under-dense environment and probe intergalactic magnetic fields using the Faraday rotation properties of their radio lobes. We use RM synthesis in the 120-168 MHz band to search for polarized emission and to derive the RM and fractional polarization of each detected source component. We study the depolarization between 1.4 GHz and 144 MHz using images from the NVSS. From a sample of 240 GRGs, we detected 37 sources in polarization, all with a total flux density above 56 mJy. The fractional polarization of the detected GRGs at 1.4 GHz and 144 MHz is consistent with a small amount of Faraday depolarization (a Faraday dispersion $<$ 0.3 rad m${}^{-2}$). Our analysis shows that the lobes are expanding into a low-density ($<10^{-5}$ cm${}^{-3}$) local environment permeated by weak magnetic fields ($<$0.1 $\mu$G) with fluctuations on scales of 3 to 25 kpc. The presence of foreground galaxy clusters appears to influence the polarization detection rate up to 2R${}_{500}$. In general, this work demonstrates the ability of LOFAR to quantify the rarefied environments in which these GRGs exist and highlights them as an excellent statistical sample to use as high precision probes of magnetic fields in the intergalactic medium and the Milky Way.

arXiv comment25 pages, 9 figures, 3 tables, accepted by A&A

References in corpus (55)

• Astropy: A Community Python Package for Astronomy
• The Sloan Digital Sky Survey: Technical Summary
• A Cosmology Calculator for the World Wide Web
• WSClean: an implementation of a fast, generic wide-field imager for radio astronomy
• Baryons in the Warm-Hot Intergalactic Medium
• Faraday Rotation Measure Synthesis
• The LOFAR Two-metre Sky Survey - I. Survey Description and Preliminary Data Release
• The LOFAR Two-metre Sky Survey - II. First data release
• A New Radio - X-Ray Probe of Galaxy Cluster Magnetic Fields
• A catalog of 132,684 clusters of galaxies identified from Sloan Digital Sky Survey III
• The Coma cluster magnetic field from Faraday rotation measures
• A GMBCG Galaxy Cluster Catalog of 55,424 Rich Clusters from SDSS DR7
• LOFAR facet calibration
• Magnetic Fields and Faraday Rotation in Clusters of Galaxies
• LOFAR 150-MHz observations of the Boötes field: Catalogue and Source Counts
• Faceting for direction-dependent spectral deconvolution
• Estimating extragalactic Faraday rotation
• The LOFAR Two-metre Sky Survey (LoTSS) III. First Data Release: optical/IR identifications and value-added catalogue
• Calibrating High-Precision Faraday Rotation Measurements for LOFAR and the Next Generation of Low-Frequency Radio Telescopes
• Calibration of the optical mass proxy for clusters of galaxies and an update of the WHL12 cluster catalog
• Giant Radio Sources
• Correlation of the magnetic field and the intra-cluster gas density in galaxy clusters
• Non-linear Kalman filters for calibration in radio interferometry
• Simulations of extragalactic magnetic fields and of their observables
• Giant radio galaxies in the LOFAR Two-metre Sky Survey-I
• Integrated Polarization of Sources at lambda ~1m and New Rotation Measure Ambiguities
• Simulations of magnetic fields in filaments
• The nature of the low-frequency emission of M51: First observations of a nearby galaxy with LOFAR
• Sardinia Radio Telescope observations of Abell 194 - the intra-cluster magnetic field power spectrum
• Structure in the Rotation Measure Sky
• New constraints on the magnetization of the cosmic web using LOFAR Faraday rotation observations
• The LOFAR Two-metre Sky Survey IV. First Data Release: Photometric redshifts and rest-frame magnitudes
• Differences in Faraday Rotation Between Adjacent Extragalactic Radio Sources as a Probe of Cosmic Magnetic Fields
• LoTSS DR1: Double-double radio galaxies in the HETDEX field
• The Cosmic Large-Scale Structure in X-rays (CLASSIX) Cluster Survey I: Probing galaxy cluster magnetic fields with line of sight rotation measures
• On the relationship between a giant radio galaxy MSH 05-22 and the ambient large-scale galaxy structure
• The intergalactic magnetic field probed by a giant radio galaxy
• An updated catalogue of giant radio sources
• Faraday Rotation Observations of Magnetic Fields in galaxy Clusters
• Detection Thresholds and Bias Correction in Polarized Intensity
• Fractional polarization and magnetic fields in the ICM
• Giant radio galaxies - II. Tracers of large-scale structure
• Discovery of Giant Radio Galaxies from NVSS: Radio & Infrared Properties
• Multifrequency observations of the jets in the radio galaxy NGC 315
• Polarized point sources in the LOFAR Two-meter Sky Survey: A preliminary catalog
• Detecting shocked intergalactic gas with X-ray and radio observations
• Diffuse polarized emission in the LOFAR Two-meter Sky Survey
• Analytic Detection Thresholds for Measurements of Linearly Polarized Intensity Using Rotation Measure Synthesis
• Wide-field LOFAR imaging of the field around the double-double radio galaxy B1834+620: A fresh view on a restarted AGN and doubeltjes
• The new sample of giant radio sources III. Statistical trends and correlations
• Faraday rotation at low frequencies: magnetoionic material of the large FRII radio galaxy PKS J0636-2036
• Untangling cosmic magnetic fields: Faraday tomography at metre wavelengths with LOFAR
• LOFAR first look at the giant radio galaxy 3C 236
• Reliable detection and characterization of low-frequency polarized sources in the LOFAR M51 field
• The rotation measures of high luminosity sources as seen from the NVSS

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• Magnetic field strength in cosmic web filaments
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• The MPIfR-MeerKAT Galactic Plane survey I -- System setup and early results
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• Radio observations of the merging galaxy cluster system Abell 3391-Abell 3395
• Constraints on Large-Scale Magnetic Fields in the Intergalactic Medium Using Cross-Correlation Methods
• Constraining Magnetic Fields in the Circumgalactic Medium
• Evolution of primordial magnetic fields during large-scale structure formation
• The POlarised GLEAM Survey (POGS) II: Results from an All-Sky Rotation Measure Synthesis Survey at Long Wavelengths
• The detection of cluster magnetic fields via radio source depolarisation
• Simulations and observational tests of primordial magnetic fields from Cosmic Microwave Background constraints
• New constraints on the magnetic field in filaments of the cosmic web
• Hard X-ray selected giant radio galaxies -- III. The LOFAR view
• A low frequency study of linear polarization in radio galaxies
• Evidence for strong intracluster magnetic fields in the early Universe
• Soft gamma-ray selected giant radio galaxies: an update
• Message in a Bottle: Unveiling the Magneto-Ionic Complexity of AGNs through the Stokes QU-Fitting Technique
• Filamentary Baryons and Where to Find Them: A forecast of synchrotron radiation from merger and accretion shocks in the local Cosmic Web
• SAGAN-VI: When Jets Meet Filaments -- Environmental Imprints on the Growth of Giant Radio Galaxies
• LOFAR Deep Fields: Probing the sub-mJy regime of polarized extragalactic sources in ELAIS-N1. II. Analysis
• Simulated Rotation Measure Sky from Primordial Magnetic Fields