A Broadband Spectro-polarimetric View of the NVSS Rotation Measure Catalogue I: Breaking the nπ-ambiguity

Abstract

The NRAO VLA Sky Survey (NVSS) Rotation Measure (RM) catalogue is invaluable for the study of cosmic magnetism. However, the RM values reported in it can be affected by n$\pi$-ambiguity, resulting in deviations of the reported RM from the true values by multiples of +-652.9 rad m-2. We therefore set off to observationally constrain the fraction of sources in the RM catalogue affected by this ambiguity. New broadband spectro-polarimetric observations were performed with the Karl G. Jansky Very Large Array (VLA) at 1--2 GHz, with 23 n$\pi$-ambiguity candidates selected by their peculiarly high |RM| values. We identified nine sources with erroneous RM values due to n$\pi$-ambiguity and 11 with reliable RM values. In addition, we found two sources to be unpolarised and one source to be inconsistent with neither n$\pi$-ambiguity nor reliable RM cases. By comparing the statistical distributions of the above two main classes, we devised a measure of how much a source's RM deviates from that of its neighbours: $\Delta /\sigma$, which we found to be a good diagnostic of n$\pi$-ambiguity. With this, we estimate that there are at least 50 sources affected by n$\pi$-ambiguity among the 37,543 sources in the catalogue. Finally, we explored the Faraday complexities of our sources revealed by our broadband observations.

arXiv comment27 pages, MNRAS accepted

References in corpus (67)

• Planck 2015 results. XIII. Cosmological parameters
• The 6dF Galaxy Survey: Final Redshift Release (DR3) and Southern Large-Scale Structures
• The 2MASS Redshift Survey - Description and Data Release
• Faraday Rotation Measure Synthesis
• The Fourteenth Data Release of the Sloan Digital Sky Survey: First Spectroscopic Data from the extended Baryon Oscillation Spectroscopic Survey and from the second phase of the Apache Point Observatory Galactic Evolution Experiment
• The Second Catalog of Active Galactic Nuclei Detected by the Fermi Large Area Telescope
• A New Model of the Galactic Magnetic Field
• Planck 2013 results. XXIX. Planck catalogue of Sunyaev-Zeldovich sources
• Magnetic Field in Clusters of Galaxies
• Magnetic Fields in Spiral Galaxies
• The Wisconsin H-Alpha Mapper Northern Sky Survey
• An Accurate Flux Density Scale from 1 to 50 GHz
• Radio observational constraints on Galactic 3D-emission models
• GASS: The Parkes Galactic All-Sky Survey. I. Survey Description, Goals, and Initial Data Release
• An improved map of the Galactic Faraday sky
• The Westerbork SINGS Survey II. Polarization, Faraday Rotation, and Magnetic Fields
• The magnetic field of the Large Magellanic Cloud revealed through Faraday rotation
• The Effelsberg-Bonn HI Survey: Milky Way gas. First data release
• Modeling the Magnetic Field in the Galactic Disk using New Rotation Measure Observations from the Very Large Array
• Estimating extragalactic Faraday rotation
• Complex Faraday depth structure of Active Galactic Nuclei as revealed by broadband radio polarimetry
• Radio polarization from the inner Galaxy at arcminute resolution
• A Survey of Extragalactic Faraday Rotation at High Galactic Latitude: The Vertical Magnetic Field of the Milky Way towards the Galactic Poles
• GASS: The Parkes Galactic All-Sky Survey. Update: improved correction for instrumental effects and new data release
• Nebular spectroscopy: A guide on H II regions and planetary nebulae
• Integrated Polarization Properties of 3C48, 3C138, 3C147, and 3C286
• Revealing the magnetic field in a distant galaxy cluster: discovery of the complex radio emission from MACS J0717.5 +3745
• Integrated Polarization of Sources at lambda ~1m and New Rotation Measure Ambiguities
• Magnetic Fields in Large Diameter HII Regions Revealed by the Faraday Rotation of Compact Extragalactic Radio Sources
• Detection of microgauss coherent magnetic fields in a galaxy five billion years ago
• The dynamical state of brightest cluster galaxies and the formation of clusters
• A Radio and Optical Polarization Study of the Magnetic Field in the Small Magellanic Cloud
• Rotation Measures of Radio Sources in Hot Galaxy Clusters
• Structure in the Rotation Measure Sky
• Magnetic Fields in the 3C 129 Cluster
• Magnetic Field Structure of the Large Magellanic Cloud from Faraday Rotation Measures of Diffuse Polarized Emission
• Comparison of algorithms for determination of rotation measure and Faraday structure I. 1100 - 1400 MHz
• DA495 - an aging pulsar wind nebula
• Broadband Radio Polarimetry and Faraday Rotation of 563 Extragalactic Radio Sources
• Two New Catalogues of Superclusters of Abell/ACO Galaxy Clusters out to redshift 0.15
• Detection Thresholds and Bias Correction in Polarized Intensity
• Broadband, radio spectro-polarimetric study of 100 radiative-mode and jet-mode AGN
• A radio-polarisation and rotation measure study of the Gum Nebula and its environment
• Ordered magnetic fields around radio galaxies: evidence for interaction with the environment
• A study of broadband Faraday rotation and polarization behaviour over 1.3--10 GHz in 36 discrete radio sources
• FR-II radio galaxies at low frequencies II: spectral ageing and source dynamics
• Constraints from Faraday rotation on the magnetic field structure in the Galactic halo
• Measurement of a Magnetic Field in a Leading Arm High Velocity Cloud
• Broadband radio spectro-polarimetric observations of high Faraday rotation measure AGN
• Faraday Rotation Measure Synthesis of intermediate redshift quasars as a probe of intervening matter
• Magnetized Gas in the Smith High Velocity Cloud
• Rotation measure synthesis at the 2 m wavelength of the FAN region: Unveiling screens and bubbles
• Detection of a Coherent Magnetic Field in the Magellanic Bridge through Faraday Rotation
• S-PASS/ATCA: a window on the magnetic universe in the southern hemisphere
• Spectropolarimetry with the Allen Telescope Array: Faraday Rotation toward Bright Polarized Radio Galaxies
• Detection of a ~20 kpc coherent magnetic field in the outskirt of merging spirals: the Antennae galaxies
• Radio Polarization Observations of the Snail: A Crushed Pulsar Wind Nebula in G327.1-1.1 with a Highly Ordered Magnetic Field
• Polarized synchrotron radiation from the Andromeda Galaxy M31 and background sources at 350 MHz
• Constraining the Magnetic Field of the Smith High Velocity Cloud using Faraday rotation
• Finding a faint polarized signal in wide-band radio data
• Finding a complex polarized signal in wide-band radio data
• Denser Sampling of the Rosette Nebula with Faraday Rotation Measurements: Improved Estimates of Magnetic Fields in HII Regions
• Extreme jet bending on kiloparsec scales : the 'doughnut' in NGC 6109
• Performance test of QU-fitting in cosmic magnetism study
• Revealing the Faraday Depth Structure of Radio Galaxy NGC 612 with Broad-Band Radio Polarimetric Observations
• The Magnetic Field of the H~II Region NGC 6334A
• The Lacerta OB1 Association

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• The coherent magnetic field of the Milky Way halo, Local Bubble and Fan Region
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• The Global Magneto-Ionic Medium Survey (GMIMS): The brightest polarized region in the Southern sky at 75cm and its implications for Radio Loop II
• The contribution of magnetized galactic outflows to extragalactic Faraday rotation
• Polarised radiative transfer, rotation measure fluctuations and large-scale magnetic fields
• The Galactic latitude dependency of Faraday complexity in the S-PASS/ATCA RM catalogue
• Distant probes of RM structure -- Where is the Faraday Rotation towards the Magellanic Leading Arm?
• The Galactic Faraday rotation sky 2020
• Modeling Local Bubble analogs II: Synthetic Faraday rotation maps
• A new window into the sub-parsec scale magnetic field in the Milky Way? Unveiling small-scale magneto-ionic structures with Faraday complexity
• Testing the correlation between bending angle and polarization properties of bent radio galaxies