A complete sample of radio sources in the North Ecliptic Cap, selected at 38 MHz – III. Further imaging observations and the photometric properties of the sample |
| |
| Authors: | Mark Lacy Mary Elizabeth Kaiser Gary J Hill Steve Rawlings Gareth Leyshon |
| |
| Institution: | Astrophysics, Department of Physics, Keble Road, Oxford OX1 3RH; McDonald Observatory, University of Texas at Austin, TX 78712-1083, USA; Bloomberg Center for Physics and Astronomy, John Hopkins University, 3400 Charles Street, Baltimore, MD 21218, USA; Astronomy Department, University of Wales College of Cardiff, PO Box 913, Cardiff CF2 3YB |
| |
| Abstract: | Further imaging observations of a sample of radio sources in the North Ecliptic Cap are presented and a number of new identifications are made. Using redshifts from spectroscopic data presented in a companion paper by Lacy et al., the photometric properties of the galaxies in the sample are discussed. It is shown that: (1) out to at least z ≈0.6 radio galaxies are good standard candles irrespective of radio luminosity; (2) for 0.6≲ z ≲1 a large fraction of the sample has magnitudes and colours consistent with a non-evolving giant elliptical, and (3) at higher redshifts, where the R -band samples the rest-frame UV flux, most objects have less UV luminosity than expected if they form their stellar populations at a constant rate from a high redshift to z ∼1 in unobscured star-forming regions (assuming an Einstein–de Sitter cosmology). The consequences of these observations are briefly discussed. |
| |
| Keywords: | galaxies: active galaxies: evolution galaxies: formation radio continuum: galaxies |
|
|
