Discovery of an Ultra-Steep Spectrum, Highly Polarized Red Quasar at z = 1.462

Abstract

We report the discovery of WN J0717+4611, a highly polarized red quasar at z=1.462, selected from a sample of faint (S_{1.4GHz} > 10 mJy) ultra steep spectrum (alpha < -1.3) radio sources. VLA observations at 4.85 GHz show that the radio source is dominated by a 21 mJy core. Using the Keck telescopes, we obtained spectra with a combined wavelength range covering 4000 Angstroms to 1.6 microns, and spectropolarimetric observations between 4000 Angstroms and 9000 Angstroms. We identify WN J0717+4611 as a quasar based on broad emission of Mg II 2799 (FWHM ~ 11,000 km/s), a stellar R_S band Lick image and the high luminosity of the object (M_B = -24.2). The optical linear polarization is wavelength-independent at 15% in both the continuum and the emission lines, with the polarization angle orthogonal to the radio jet axis. We argue that the polarization mechanism is scattering of quasar light by surrounding small dust grains or electrons. WN J0717+4611 appears highly reddened for a core-dominated quasar.

20 Pages, including 2 tables and 4 PostScript figures; Accepted for publication in the Astronomical Journal (1998 July issue)

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Cited by in corpus (12)

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• Multiwavelength characterization of faint Ultra Steep Spectrum radio sources : A search for high-redshift radio galaxies
• Spectropolarimetry of 3CR 68.1: A Highly Inclined Quasar
• The Spectral Signature of Dust Scattering and Polarization in the Near IR to Far UV. I. Optical Depth and Geometry Effects
• The 6C** sample of steep-spectrum radio sources: I - Radio data, near-infrared imaging and optical spectroscopy
• Optical Polarization of 52 Radio-Loud QSOs and BL Lac Objects
• Ultra Steep Spectrum radio sources in the Lockman Hole: SERVS identifications and redshift distribution at the faintest radio fluxes
• The first ISO ERO: a dusty quasar at z = 1.5
• MIGHTEE: exploring the relationship between spectral index, redshift and radio luminosity