The distribution of polarized radio sources $>$15$\mu$Jy in GOODS-N

Abstract

We present deep VLA observations of the polarization of radio sources in the GOODS-N field at 1.4 GHz at resolutions of 1.6" and 10". At 1.6", we find that the peak flux cumulative number count distribution is N($>$p) $\sim$ 45 * (p/30$\mu$Jy)${}^{-0.6}$ per square degree above a detection threshold of 14.5 $\mu$Jy. This represents a break from the steeper slopes at higher flux densities, resulting in fewer sources predicted for future surveys with the SKA and its precursors. It provides a significant challenge for using background RMs to study clusters of galaxies or individual galaxies. Most of the polarized sources are well above our detection limit, and are radio galaxies which are well-resolved even at 10", with redshifts from $\sim$0.2 - 1.9. We determined a total polarized flux for each source by integrating the 10" polarized intensity maps, as will be done by upcoming surveys such as POSSUM. These total polarized fluxes are a factor of 2 higher, on average, than the peak polarized flux at 1.6"; this would increase the number counts by $\sim$50% at a fixed flux level. The detected sources have rotation measures (RMs) with a characteristic rms scatter of $\sim$11$\frac{rad}{m^2}$ around the local Galactic value, after eliminating likely outliers. The median fractional polarization from all total intensity sources does not continue the trend of increasing at lower flux densities, as seen for stronger sources. The changes in the polarization characteristics seen at these low fluxes likely represent the increasing dominance of star-forming galaxies.

Published in ApJ; this version contains corrections which will appear as an Erratum to the published version; 18 pages, 15 figures

References in corpus (8)

• Science With The Australian Square Kilometre Array Pathfinder
• The intracluster magnetic field power spectrum in Abell 2255
• The Deep SWIRE Field I. 20cm Continuum Radio Observations: A Crowded Sky
• A Radio and Optical Polarization Study of the Magnetic Field in the Small Magellanic Cloud
• Radio Polarimetry of the ELAIS N1 Field: Polarized Compact Sources
• Magnetic field structures of galaxies derived from analysis of Faraday rotation measures, and perspectives for the SKA
• Multifrequency VLA observations of the FR I radio galaxy 3C 31: morphology, spectrum and magnetic field
• Deep, wide-field, global VLBI observations of the Hubble Deep Field North and Flanking Fields

Cited by in corpus (28)

• Resolved magnetic dynamo action in the simulated intracluster medium
• Comparison of algorithms for determination of rotation measure and Faraday structure I. 1100 - 1400 MHz
• The challenges of low-frequency radio polarimetry: lessons from the Murchison Widefield Array
• Degree of Polarization and Source Counts of Faint Radio Sources from Stacking Polarized Intensity
• ATLAS 1.4 GHz Data Release 2 -- II. Properties of the faint polarized sky
• The intra-cluster magnetic field in the double relic galaxy cluster Abell 2345
• Early Science from POSSUM: Shocks, turbulence, and a massive new reservoir of ionised gas in the Fornax cluster
• Magnetic field disorder and Faraday effects on the polarization of extragalactic radio sources
• Cosmic Magnetism in Centimeter and Meter Wavelength Radio Astronomy
• The eMERGE Survey I: Very Large Array 5.5 GHz observations of the GOODS-North Field
• Nature of Faint Radio Sources in GOODS-North and GOODS-South Fields - I. Spectral Index and Radio-FIR Correlation
• Statistical Techniques for Detecting the Intergalactic Magnetic Field from Large Samples of Extragalactic Faraday Rotation Data
• The detection of cluster magnetic fields via radio source depolarisation
• Rotation measure structure functions with higher-order stencils as a probe of small-scale magnetic fluctuations and its application to the Small and Large Magellanic Clouds
• Probing cluster magnetism with embedded and background radio sources in Planck clusters
• Nowhere to Hide: Radio-faint AGN in the GOODS-N field. II. Multi-wavelength AGN selection techniques and host galaxy properties
• Radio galaxies and their magnetic fields out to z <= 3
• Simulations of the polarized radio sky and predictions on the confusion limit in polarization for future radio surveys
• The MeerKAT Fornax Survey IV. A close look at the cluster physics through the densest rotation measure grid
• A low frequency study of linear polarization in radio galaxies
• Source Finding in Linear Polarization for LOFAR, and SKA Predecessor Surveys, using Faraday Moments
• The Apertif science verification campaign - Characteristics of polarised radio sources
• Faint polarised sources in the Lockman Hole field at 1.4 GHz
• The XXL Survey: XXXIX. Polarised radio sources in the XXL-South field
• The ViCTORIA project: description of a multi-frequency radio survey of the Virgo galaxy cluster
• Properties of Compact Faint Radio Sources as a Function of Angular Size from Stacking
• Testing the correlation between bending angle and polarization properties of bent radio galaxies
• Properties of Polarized Radio Sources in the Wide Chandra Deep Field South from 2 to 4GHz