GTC optical imaging of extremely red 5C radio galaxies at high redshift

Abstract

We investigate the nature of seven unusual radio galaxies from the 5C catalogue that were previously known to have extremely red R-K colours, and for which emission lines were previously found to be weak or absent in their optical spectra. We present and discuss u, g, or r images of these radio galaxies, obtained using the Optical System for Imaging and low-Intermediate-Resolution Integrated Spectroscopy (OSIRIS) at the Gran Telescopio Canarias (GTC). We have detected all seven targets in our g-band imaging. Their optical emission is extended, and we tentatively detect a radio-optical alignment effect in this sample. A subset of our sample (three sources) shows broad-band spectral energy distributions that flatten out near the wavelength range of the g-band, implying a dominant contribution there due to young stars and/or scattered or reprocessed radiation from the active nucleus.

4 pages, 3 Figures, accepted for publication in Astronomy & Astrophysics

References in corpus (7)

• Stellar population synthesis at the resolution of 2003
• Distant Radio Galaxies and their Environments
• The Massive Hosts of Radio Galaxies Across Cosmic Time
• Near-infrared imaging and the K-z relation for radio galaxies in the 7C Redshift Survey
• Rapidly growing black holes and host galaxies in the distant Universe from the Herschel Radio Galaxy Evolution Project
• Optical spectroscopy of radio galaxies in the 7C Redshift Survey
• Witnessing the transformation of a quasar host galaxy at z=1.6

Cited by in corpus (2)

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