0 A Progress Report on the Caltech Faint

I review recent progress on determining the SEDs and luminosity functions for galaxies in the large magnitude limited sample in the region of the HDF-North of the Caltech Faint Galaxy Redshift Survey. 1. Spectral Energy Distributions and Galaxy Luminosity Functions The Caltech Faint Galaxy Redshift Survey, of which I am the PI, has assembled a redshift survey, described in Cohen et al. (2000), of objects in the region of the HDF-N observed with the LRIS (Oke et al. 1995) at the Keck Observatory over the past four years. It includes redshifts for about 95% of the sample of objects in the photometric catalog of Hogg et al. (1999) with R < 24 within the HDF itself, and for about 93% of the sample of objects with R < 23.5 within a circle of diameter 8 arcmin centered on the HDF, currently 729 objects with measured z in total. The analysis of this data set has commenced, and several papers from our group have already been published. Carlberg et al. (2000) discuss the kinematic pairs and their implications for the merger rate, Hogg, Cohen & Blandford (2000) analyzes clustering of galaxies, and van den Bergh et al. (2000) deals with the evolution of galaxy morphology, all to z ∼ 1. We thus focus here on not yet published current and future work. The logical next step is a derivation of the luminosity function for this very complete faint sample of field galaxies. We have utilized the photometric catalogs appropriate for our HDF sample and used them to derive the rest frame SEDs of the galaxies. In order to do this, one must adopt a model for the SED of a galaxy. We adopt the model of a double power law, whose index changes at 4000 Å, for Fν . While by no means a perfect representation of galaxy SEDs in their full complexity, this simple model permits an illuminating comparison of rest frame properties of galaxies. A histogram of the two power law indices as a function of galaxy spectral type is shown for our sample in the region of the HDF in figures 1a,b. The galaxy spectral types are defined from our spectra and refer to the relative dominance of emission or absorption lines in our galaxy spectra. See Cohen et al. (1999a) for details. Based in large part on observations obtained at the W.M. Keck Observatory, which is operated jointly by the California Institute of Technology and the University of California Palomar Observatory, Mail Stop 105-24, California Institute of Technology, Pasadena, CA 91125