The UNAM-KIAS catalog of isolated galaxies

A new catalog of isolated galaxies from the Sloan Digital Sky Survey Data Release 5 (SDSS DR5) is presented. A total of 1520 isolated galaxies were found in 1.4 sr of sky. The selection criteria in this UNAM-KIAS catalog are a variation on the criteria developed by Karachentseva, including full redshift information. Through an image processing pipeline that takes advantage of the high-resolution (~0farcs4 pixel–1) and high dynamic range of the SDSS images, a uniform g-band morphological classification for all these galaxies is presented. We identify 80% (Sa-Sm) spirals (50% later than Sbc types) on one hand, and a scarce population of early-type E (6.5%) and S0 (8%) galaxies amounting to 14.5% on the other hand. This magnitude-limited catalog is ~80% complete at 16.5, 15.6, 15.2, 14.6, and 14.4 mag in the ugriz bands, respectively. Some representative physical properties including SDSS magnitudes and color distributions, color-color diagrams, absolute magnitude-color, and concentration-color diagrams as a function of morphological type are presented. The UNAM-KIAS Morphological Atlas is also released along with this paper. For each galaxy of a type later than Sa, a mosaic is presented that includes (1) a g-band logarithmic image, (2) a g-band filtered-enhanced image where a Gaussian kernel of various sizes was applied, and (3) a red giant branch color image from the SDSS database. For E/S0/Sa galaxies, in addition to the images in (1), (2), and (3), plots of r-band surface brightness and geometric profiles (ellipticity ϵ, position angle PA, and A 4/B 4 coefficients of the Fourier series expansions of deviations of a pure ellipse) are provided. The size of the sample, the redshift completeness, the availability of high-quality multicolor photometric data and detailed morphological and spectroscopic information make the UNAM-KIAS catalog of isolated galaxies a suitable sample to address important issues such as (1) comparative studies of environmental effects, (2) constraining the currently competing scenarios of galaxy formation and evolution, (3) the nature and evolution of elliptical and spiral galaxies in the field, (4) the spectral properties of a statistically significant number of isolated galaxies and their evolution as a function of redshift, and (5) the fraction of active galactic nuclei in isolated environments, among other important topics. The optimization and estimation of new structural parameters as well as important information to complement existing ones in other wavelengths is being carried out