Open AccessOptical spectroscopy of radio galaxies in the 7C Redshift Survey
Author(s) -
Willott Chris J.,
Rawlings Steve,
Blundell Katherine M.,
Lacy Mark,
Hill Gary J.,
Scott Susan E.
Publication year - 2002
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2002.05718.x
Subject(s) - physics , astrophysics , radio galaxy , quasar , redshift , astronomy , luminous infrared galaxy , galaxy , spectroscopy , sky , redshift survey , luminosity , elliptical galaxy
We present optical spectroscopy of all 49 radio galaxies in the 7C‐I and 7C‐II regions of the 7C Redshift Survey (7CRS). The low‐frequency (151 MHz) selected 7CRS sample contains all sources with flux‐densities S 151 > 0.5 Jy in three regions of the sky; 7C‐I and 7C‐II were chosen to overlap with the 5C 6 and 5C 7 surveys, respectively, and cover a total sky area of 0.013 sr. The sample has been completely identified and spectroscopy of the quasars and broad‐lined radio galaxies has been presented previously by Willott et al. Only seven of the radio galaxies do not have redshift determinations from the spectroscopy, giving a redshift completeness for the sample of >90 per cent. The median redshift of the 7CRS is 1.1. We present a composite 0.2> z < 0.8 7CRS radio galaxy spectrum and investigate the strengths of the 4000‐Å breaks in these radio galaxies. We find an anti‐correlation between the 4000‐Å break strength and emission line luminosity, indicating that departures from old elliptical galaxy continuum shapes are most likely due to non‐stellar emission associated with the active nucleus.