Near-infrared and optical broadband surface photometry of 86 face-on disk dominated galaxies. II. A two-dimensional method to determine bulge and disk parameters

摘要

In this paper I present a new two-dimensional decomposition technique, whichmodels the surface photometry of a galaxy with an exponential light profile forboth bulge and disk and, when necessary, with a Freeman bar. The new techniquewas tested for systematic errors on both artificial and real data and comparedwith widely used one-dimensional decomposition techniques, where the luminosityprofile of the galaxy is used. The comparisons indicate that a decomposition ofthe two-dimensional image of the galaxy with an exponential light profile forboth bulge and disk yields the most reproducible and representative bulge anddisk parameters. An extensive error analysis was made to determine the reliability of themodel parameters. If the model with an exponential bulge profile is areasonable description of a galaxy, the maximum errors in the derived modelparameters are of order 20%. The uncertainties in the model parameters willincrease, if the exponential bulge function is replaced by other often usedbulge functions as the de Vaucouleurs law. All decomposition methods were applied to the optical and near-infrared dataset presented by de Jong & van der Kruit (1994), which comprises 86 galaxies insix passbands.