Environmental Density vs. Colour Indices of the Low Redshifts Galaxies

• Published in: Astrophysics 2015-06, Vol.58 (2), p.168-180
• Main Authors: Dobrycheva, D. V., Melnyk, O. V., Vavilova, I. B., Elyiv, A. A.
• Format: Article
• Language: English
• Subjects: Astronomy; Astrophysics; Astrophysics and Astroparticles; Astrophysics and Cosmology; Color; Colour; Density; Galaxies; Inverse; Morphology; Observations; Observations and Techniques; Physics; Physics and Astronomy; Red shift; Satellites; Space Exploration and Astronautics; Space Sciences (including Extraterrestrial Physics; Stars & galaxies; Tessellation
• ISSN: 0571-7256; 1573-8191
• DOI: 10.1007/s10511-015-9373-x

We have used 3D Voronoi tessellation to determine the environmental density of galaxies from a sample of the SDSS DR9 survey (0.02 < z < 0.1 and mr < 17.7). The sample was divided into two groups: bright central galaxies with M r < -20.7 (N ~ 120000) and faint satellite galaxies with M r > -20.7 (N~140000). We characterized the environmental density of the galaxies by the inverse volume of a Voronoi cell. We confirmed a tendency for an evolutionary decrease in the relative number of early galaxy types (with quenched star formation) with increasing redshift. It was also shown that the higher the density of environment near a central galaxy, it is more likely that the central galaxy has an early morphological type. The fraction of early types among the central galaxies is higher (78%) that among the sample of satellite galaxies (26%). In addition, the higher fraction of the central early-type galaxies in the sample, the higher their share in the denser environments.