Spectral energy distributions for galaxies in high redshift clusters.I. Methods and application to three clusters with 0.22 ≤ z ≤ 0.31.
Using CCDs and a range of intermediate band filters, three moderate redshift (z = 0.22-0.31) clusters were imaged and low-resolution spectral energy distributions for about 50 galaxies per cluster to a limit of R(f) = 21 were derived. The average flux distributions are in good agreement with those expected from published K-corrections and local knowledge of the color-luminosity relation for early-type galaxies; the brightest members do not appear to be anomalous. Some blue galaxies are found: their average spectral energy distribution approximates to an Sbc galaxy at the cluster redshift. At the longest wavelength studied (860 nm) some galaxies are significantly redder than the cluster average; the nature of these objects remains unclear but they do appear to be cluster members. The important question of whether there is any evolution in the early-type population depends sensitively on corrections made for foreground reddening and for the color-luminosity relations. With some uncertainties there is room for a small amount of evolution consistent with previous estimates. At higher redshifts where evolutionary effects are expected to be larger the technique will be a powerful way to study large galaxy samples at known epochs.
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- December 1983
- Galactic Clusters;
- Galactic Evolution;
- Red Shift;
- Spectral Energy Distribution;
- Bandpass Filters;
- Charge Coupled Devices;
- Error Analysis;
- Interstellar Extinction;
- Clusters of Galaxies:Redshifts;
- Galaxies:Energy Distribution;
- Redshifts:Clusters of Galaxies