We describe an algorithm that measures self-consistently the relative galaxy contribution in a sample of radio quasars from their optical spectra alone. This is based on a spectral fitting method which uses the size of the characteristic 4000Angstroms feature of elliptical galaxy spectral energy distributions. We apply this method to the Parkes half-Jansky flat-spectrum sample of Drinkwater et al. to determine whether emission from the host galaxy can significantly contribute to the very red optical to near-infrared colours observed. We find that at around 2sigma confidence, most of the reddening in unresolved (mostly quasar-like) sources is unlikely to be the result of contamination by a red stellar component.
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- December 1998
- METHODS: ANALYTICAL;
- GALAXIES: FUNDAMENTAL PARAMETERS;
- QUASARS: GENERAL;
- 11 pages, 11 figures. Accepted for Publication in Monthly Notices of the Royal Astronomical Society