Caltech Faint Galaxy Redshift Survey XIII: Spectral Energy Distributions for Galaxies in the Region of the Hubble Deep Field North

Abstract

We introduce a new empirical function for modeling the spectral energy distributions of galaxies. We apply it to a sample of 590 galaxies in the region of the HDF with $z < 1.5$ using multi-color photometry with wide wavelength coverage combined with spectroscopic redshifts from our 93% complete R-selected redshift survey there. We find the following: As expected, galaxies with strong signs of recent star formation (i.e. those which show emission lines) have bluer continua in both the rest frame UV and the optical/near-infrared. The redder galaxies tend to be more luminous. The SEDs of actively star forming galaxies become bluer in the mean in the rest-frame UV at higher redshift, which trend might arise from SED modeling errors. Aside from this, we discern no change with redshift in the relationship between SED characteristics and galaxy spectral type based on the strength of narrow emission and absorption features. There is no evidence in our R-selected sample that supports the existence of a substantial population of very dusty star forming galaxies at z < 1.5. The overall pattern of the L(K) - z relationship suggests that passive evolution at constant stellar mass is a good approximation to the actual behavior of at least the most luminous galaxies in this large sample of galaxies in the region of the HDF out to z \sim 1.5. (abridged)