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

A. Humphrey, M. Villar Martín, P. Lagos

Aims. 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.
Methods. 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).
Results. 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.

galaxies: active, galaxies: evolution, galaxies: high-redshift, galaxies: jets, quasars: general, galaxies: star formation

Astronomy & Astrophysics
Volume 585, Article Number A32, Number of pages 4
2016 January

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Faculdade de Ciências da Universidade de Lisboa Universidade do Porto Faculdade de Ciências e Tecnologia da Universidade de Coimbra
Fundação para a Ciência e a Tecnologia COMPETE 2020 PORTUGAL 2020 União Europeia