Photometric redshifts of galaxiesStephen Donald Jermy Gwyn.
Date
1995
Authors
Gwyn, Stephen Donald Jermy
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Abstract
This thesis presents a method to measure the redshifts, z, of galaxies using broadband photometry. In this method, the photometry of observed galaxies is converted into low resolution spectral energy distributions by converting BVRI magnitudes into fluxes. Template galaxy spectra are obtained by redshifting the spectra of local galaxies. Redshifts are determined by comparing the observed spectral energy distributions to these templates. Photometric data for galaxies of known spectroscopic redshift were obtained at the Canada France Hawaii Telescope to test the accuracy of this method. It was found that, if the templates are modified for evolution using either theoretical models or empirical corrections, the accuracy improves. With these modifications, the method is accurate to Δz = ± 0.125. The efficacy and speed with which the properties of a large number of galaxies can be determined using photometric redshifts was demonstrated by measuring the luminosity function for a sample of 187 moderate redshift (<z>= .34) galaxies