Three-dimensional modelling of edge-on disk galaxies

Abstract

We present detailed three-dimensional modelling of the stellar luminosity distribution for the disks of 31 relatively nearby (<= 110 Mpc) edge-on spiral galaxies. In contrast to most of the standard methods available in the literature we take into account the full three-dimensional information of the disk. We minimize the difference between the observed 2D-image and an image of our 3D-disk model integrated along the line of sight. Thereby we specify the inclination, the fitting function for the z-distribution of the disk, and the best values for the structural parameters such as scalelength, scaleheight, central surface brightness, and a disk cut-off radius. From a comparison of two independently developed methods we conclude, that the discrepancies e.g. for the scaleheights and scalelengths are of the order of ~10%. These differences are not due to the individual method itself, but rather to the selected fitting region, which masks the bulge component, the dust lane, or present foreground stars. Other serious limitations are small but appreciable intrinsic deviations of real disks compared to the simple input model. In this paper we describe the methods and present contour plots as well as radial profiles for all galaxies without previously published surface photometry. Resulting parameters are given for the complete sample.