The HST/ACS Coma Cluster Survey - III. Structural parameters of galaxies using single Sersic fits☆

We present a catalogue of structural parameters for 8814 galaxies in the 25 fields of the Hubble Space Telescope/ACS Coma Treasury Survey. Parameters from Sersic fits to the two-dimensional surface brightness distributions are given for all galaxies from our published Coma photometric catalogue with mean effective surface brightness brighter than 26.0 mag arcsec-2 and brighter than 24.5 mag (equivalent to absolute magnitude -10.5), as given by the fits, all in F814W(AB). The sample comprises a mixture of Coma members and background objects; 424 galaxies have redshifts and of these 163 are confirmed members. The fits were carried out using both the gim2d and galfit codes. We provide the following parameters: galaxy ID, RA, Dec., the total corrected automatic magnitude from the photometric catalogue, the total magnitude of the model (F814W(AB)), the geometric mean effective radius R-e, the mean surface brightness within the effective radius <<mu >>(e), the Sersic index n, the ellipticity and the source position angle. The selection limits of the catalogue and the errors listed for the Sersic parameters come from extensive simulations of the fitting process using synthetic galaxy models. The agreement between gim2d and galfit parameters is sensitive to details of the fitting procedure; for the settings employed here the agreement is excellent over the range of parameters covered in the catalogue. We define and present two goodness-of-fit indices which quantify the degree to which the image can be approximated by a Sersic model with concentric, coaxial elliptical isophotes; such indices may be used to objectively select galaxies with more complex structures such as bulge-disc, bars or nuclear components. We make the catalogue available in electronic format at astro-wise and MAST.