Radio sources with ultra-high polarization

Abstract

A sample of 129 unresolved radio sources with ultrahigh linear polarization (>30 per cent) has been selected from the NRAO VLA Sky Survey. Such high average linear polarization is unusual in extragalactic sources. Higher resolution Australia Telescope Compact Array and Very Large Array observations confirm the high average polarization but find that most of these sources are extended. The Sloan Digital Sky Survey spectroscopy, where available, shows that the optical counterparts are elliptical galaxies with no detectable emission lines. The optical spectra, radio luminosity, linear size and spectral index of these sources are typical of radio-loud active galactic nuclei. Galaxy counts within a 1 Mpc radius of the radio sources show that these highly polarized sources are in environments similar to their low polarization (<2 per cent) counterparts. Similarly, the line-of-sight environments of the ultrahigh polarization sources are on average indistinguishable from those of the low-polarization sources. We conclude that the extraordinarily high average polarization must be due to intrinsic properties of the sources, such as an extremely ordered source magnetic field, low internal thermal plasma density or a preferential orientation of the source magnetic field perpendicular to the line of sight.

23 pages, 15 figures, 6 tables, accepted for publication in MNRAS; v2: some typos corrected

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• COrE (Cosmic Origins Explorer) A White Paper
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• ATLAS 1.4 GHz Data Release 2 -- II. Properties of the faint polarized sky
• The impact of polarized extragalactic radio sources on the detection of CMB anisotropies in polarization
• Polarized Radio Sources: A Study of Luminosity, Redshift and Infrared Colors
• The Magnetic Field and Polarization Properties of Radio Galaxies in Different Accretion States
• Radio galaxies and their magnetic fields out to z <= 3
• One blind and three targeted searches for (sub)millisecond pulsars
• One of Everything: The Breakthrough Listen Exotica Catalog