<i>K</i>-Corrections and Filter Transformations in the Ultraviolet, Optical, and Near-Infrared

Abstract

Template fits to observed galaxy fluxes allow calculation of K-corrections and conversions among observations of galaxies at various wavelengths. We present a method for creating model-based template sets given a set of heterogeneous photometric and spectroscopic galaxy data. Our technique, non-negative matrix factorization, is akin to principle component analysis (PCA), except that it is constrained to produce nonnegative templates, it can use a basis set of models (rather than the delta function basis of PCA), and it naturally handles uncertainties, missing data, and heterogeneous data (including broad-band fluxes at various redshifts). The particular implementation we present here is suitable for ultraviolet, optical, and near-infrared observations in the redshift range 0 < z < 1.5. Since we base our templates on stellar population synthesis models, the results are intepretable in terms of approximate stellar masses and star-formation histories. We present templates fit with this method to data from GALEX, Sloan Digital Sky Survey spectroscopy and photometry, the Two-Micron All Sky Survey, the Deep Extragalactic Evolutionary Probe and the Great Observatories Origins Deep Survey. In addition, we present software for using such data to estimate K-corrections and stellar masses.