Differences in Faraday Rotation Between Adjacent Extragalactic Radio Sources as a Probe of Cosmic Magnetic Fields

Abstract

Faraday rotation measures (RMs) of extragalactic radio sources provide information on line-of-sight magnetic fields, including contributions from our Galaxy, source environments, and the intergalactic medium (IGM). Looking at differences in RMs, $\Delta$RM, between adjacent sources on the sky can help isolate these different components. In this work, we classify adjacent polarized sources in the NVSS as random or physical pairs. We recompute and correct the uncertainties in the NVSS RM catalog, since these were significantly overestimated. Our sample contains 317 physical and 5111 random pairs, all with Galactic latitudes $|b|\ge 20^{\circ }$, polarization fractions $\ge 2\%$, and angular separations between $1{.}^{{}^{\prime }},$ and $20^{{}^{\prime }}$. We find an rms $\Delta$RM of $14.9\pm 0.4$rad m${}^{-2}$ and $4.6\pm 1.1$rad m${}^{-2}$ for random and physical pairs, respectively. This means polarized extragalactic sources that are close on the sky, but at different redshifts, have larger differences in RM than two components of one source. This difference of $\sim 10$rad m${}^{-2}$ is significant at $5\sigma$, and persists in different data subsamples. While there have been other statistical studies of $\Delta$RM between adjacent polarized sources, this is the first unambiguous demonstration that some of this RM difference must be extragalactic, thereby providing a firm upper limit on the RM contribution of the IGM. If the $\Delta$RMs originate local to the sources, then the local magnetic field difference between random sources is a factor of two larger than between components of one source. Alternatively, attributing the difference in $\Delta$RMs to the intervening IGM yields an upper limit on the IGM magnetic field strength of $40$nG.

26 pages, 13 figures, 3 tables. Accepted for publication in ApJ

References in corpus (49)

• The Wide-field Infrared Survey Explorer (WISE): Mission Description and Initial On-orbit Performance
• The 2dF Galaxy Redshift Survey: Spectra and redshifts
• The Ninth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the SDSS-III Baryon Oscillation Spectroscopic Survey
• The Eighth Data Release of the Sloan Digital Sky Survey: First Data from SDSS-III
• The 6dF Galaxy Survey: Final Redshift Release (DR3) and Southern Large-Scale Structures
• The GMRT 150 MHz All-sky Radio Survey: First Alternative Data Release TGSS ADR1
• Cluster Magnetic Fields
• Faraday Rotation Measure Synthesis
• The 2dF QSO Redshift Survey - XII. The spectroscopic catalogue and luminosity function
• The 6dF Galaxy Survey: Samples, Observational Techniques and the First Data Release
• Magnetic Field in Clusters of Galaxies
• Turbulence and Magnetic Fields in the Large Scale Structure of the Universe
• Pulsar rotation measures and the large-scale structure of Galactic magnetic field
• An improved map of the Galactic Faraday sky
• 2MASS Photometric Redshift catalog: a comprehensive three-dimensional census of the whole sky
• Photometric redshifts for the SDSS Data Release 12
• Estimating extragalactic Faraday rotation
• Complex Faraday depth structure of Active Galactic Nuclei as revealed by broadband radio polarimetry
• A Unified Catalog of Radio Objects Detected by NVSS, FIRST, WENSS, GB6, and SDSS
• A Survey of Extragalactic Faraday Rotation at High Galactic Latitude: The Vertical Magnetic Field of the Milky Way towards the Galactic Poles
• Radio Galaxy Zoo: host galaxies and radio morphologies derived from visual inspection
• On the amplification of magnetic fields in cosmic filaments and galaxy clusters
• Simulations of extragalactic magnetic fields and of their observables
• WISE x SuperCOSMOS photometric redshift catalog: 20 million galaxies over 3pi steradians
• A radio spectral index map and catalogue at 147-1400 MHz covering 80 per cent of the sky
• Integrated Polarization of Sources at lambda ~1m and New Rotation Measure Ambiguities
• A new sample of large angular size radio galaxies. I. The radio data
• Structure in the Rotation Measure Sky
• Observational constraints on models for the interstellar magnetic field in the Galactic disk
• Faraday Rotation Measure due to the Intergalactic Magnetic Field
• Forecasts for the detection of the magnetised cosmic web from cosmological simulations
• Magnetic Fields and Ionized Gas in the inner Galaxy: An Outer Scale for Turbulence and the Possible Role of HII Regions
• A Broadband Polarization Catalog of Extragalactic Radio Sources
• The intergalactic magnetic field probed by a giant radio galaxy
• Low Frequency Radio Constraints on the Synchrotron Cosmic Web
• A catalogue of photometric redshifts for the SDSS-DR9 galaxies
• Quasar Probabilities and Redshifts from WISE mid-IR through GALEX UV Photometry
• Limiting Magnetic Fields in the Cosmic Web with Diffuse Radio Emission
• Observations of a nearby filament of galaxy clusters with the Sardinia Radio Telescope
• Polarized point sources in the LOFAR Two-meter Sky Survey: A preliminary catalog
• Magnetic field disorder and Faraday effects on the polarization of extragalactic radio sources
• Using head-tail galaxies to constrain the intracluster magnetic field: an in-depth study of PKS J0334-3900
• A Selection of Giant Radio Sources from NVSS
• Faraday rotation at low frequencies: magnetoionic material of the large FRII radio galaxy PKS J0636-2036
• Simulations of cosmic rays in large-scale structures: numerical and physical effects
• Radio Polarization Properties of Quasars and Active Galaxies at High Redshifts
• The rotation measures of high luminosity sources as seen from the NVSS
• Detecting the cosmic web with radio surveys
• From the NVSS RM Catalogue to Future Polarisation Surveys

Cited by in corpus (45)

• Ultra-High-Energy Cosmic Rays: The Intersection of the Cosmic and Energy Frontiers
• Discovery of Magnetic Fields Along Stacked Cosmic Filaments as Revealed by Radio and X-Ray Emission
• New constraints on the magnetization of the cosmic web using LOFAR Faraday rotation observations
• Magnetic field strength in cosmic web filaments
• First Predicted Cosmic Ray Spectra, Primary-to-Secondary Ratios, and Ionization Rates from MHD Galaxy Formation Simulations
• The Galactic Faraday depth sky revisited
• A Large Scale Magneto-ionic Fluctuation in the Local Environment of Periodic Fast Radio Burst Source, FRB 20180916B
• Magnetic field evolution in cosmic filaments with LOFAR data
• Magnetogenesis around the first galaxies: the impact of different field seeding processes on galaxy formation
• Early Science from POSSUM: Shocks, turbulence, and a massive new reservoir of ionised gas in the Fornax cluster
• Magnetization of the intergalactic medium in the IllustrisTNG simulations: the importance of extended, outflow-driven bubbles
• Constraints on Large-Scale Magnetic Fields in the Intergalactic Medium Using Cross-Correlation Methods
• Constraining Magnetic Fields in the Circumgalactic Medium
• The LOFAR view of intergalactic magnetic fields with giant radio galaxies
• 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
• Simulations and observational tests of primordial magnetic fields from Cosmic Microwave Background constraints
• Polarized accretion shocks from the cosmic web
• New constraints on the magnetic field in filaments of the cosmic web
• The Complex Large-scale Magnetic Fields in the First Galactic Quadrant as Revealed by the Faraday Depth Profile Disparity
• Probing cluster magnetism with embedded and background radio sources in Planck clusters
• On the nature of LOFAR RMs and new constraints on magnetic fields in cosmic filaments and on magnetogenesis scenarios
• Magnetic fields in elliptical galaxies: Using the Laing-Garrington effect in radio galaxies and polarized emission from background radio sources
• The evolution of cosmic ray electrons in the cosmic web: seeding by AGN, star formation and shocks
• Evidence for strong intracluster magnetic fields in the early Universe
• A search for inter-cluster filaments with LOFAR and eROSITA
• Simulating the LOcal Web (SLOW) -- III: Synchrotron emission from the local cosmic web
• Intergalactic medium rotation measure of primordial magnetic fields
• Faint polarised sources in the Lockman Hole field at 1.4 GHz
• A new limit on intergalactic magnetic fields on sub-kpc scales from fast radio bursts
• Stacking the Synchrotron Cosmic Web with FIGARO
• Filamentary Baryons and Where to Find Them: A forecast of synchrotron radiation from merger and accretion shocks in the local Cosmic Web
• Polarised radiative transfer, rotation measure fluctuations and large-scale magnetic fields
• Revisiting primordial magnetic fields through 21-cm physics: Bounds and forecasts
• Searching for the Synchrotron Cosmic Web Again: A replication attempt
• Radio Observations as a Probe of Cosmic Web Magnetism
• Constraints on the magnetic field in the inter-cluster bridge A399-A401
• Properties of Compact Faint Radio Sources as a Function of Angular Size from Stacking
• 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
• Effects of Depolarizing Intervening Galaxies on Background Radio Emission I. Global Disk Magnetic Field
• Intergalactic magnetic field lower limits up to the redshift $z\approx 3$
• The Impact of Inhomogeneous Perturbations of the Inflaton on the Cosmological Primordial Magnetic Field
• Testing the correlation between bending angle and polarization properties of bent radio galaxies
• Primordial magnetic non-Gaussianity with generic vacua and detection prospects in CMB spectral distortions