Multicolour Optical Imaging of IR-Warm Seyfert Galaxies. III. Surface Photometry: Light Profile Decomposition

Abstract

This paper is the third in a series, studying the optical properties of a sample of mid-IR Warm Seyfert galaxies and of a control sample of mid-IR Cold galaxies. The present paper is devoted to surface photometry. We analyse the light distributions characterizing the galaxies outside the central 2 kpc. The radial light profiles are decomposed, using two generalized exponentials, in inner and outer components. Each is characterized by the profile shape, central surface brightness and scale length. We find that light is more centrally concentrated in Seyfert 1s, that also tend to lie in earlier-type hosts than Seyfert 2s. Seyfert 1 and 2 bulges have similar shapes but the former are characterized by larger central surface brightnesses and smaller scale lengths. The three parameters characterizing the bulge component correlate with each other, within a limited range of bulge luminosities. Cold galaxies are disk-dominated systems, with complex morphologies. Their bulges are flatter and fainter compared to the Warm sample. The disk structural parameters span similar ranges for the three (sub)samples but with larger scatter. The parametrization of light profiles, as described in this paper, shows that the three (sub)samples occupy different loci in parameter space, that is suggestive of an evolutionary connection between them.