It is well known that environmental effects (e.g. interactions, minor and major galaxy mergings, ram-pressure, strangulation, harassment) affect the physical properties of galaxies and Active Galactic Nuclei (AGN), such as their morphological type, colour, star formation rate (SFR), chemical composition, gas and dust content, nuclear activity, etc. Therefore both environmental and internal factors influence on galaxy evolution, however the relative importance of these two factors is not clearly established.
To study the influence of environment on the galaxy and AGN physical properties, it is necessary to have the reference sample of objects which evolution are occurring without any external influence. Such single galaxies are known in the literature as “isolated galaxies.”
The Catalog of Isolated Galaxies (KIG; Karachentseva, 1973) is the first compilation of representative sample of isolated galaxies in the Northern Sky. The physical properties of this galaxy sample are deeply considered by the AMIGA team.
Here we briefly describe our results based on the investigations of galaxy physical properties from the catalogs in compilation of which we took part:
- Catalog of nearby isolated galaxies in the volume z < 0.01; LOG.
The LOG catalog contains of 520 most isolated nearby galaxies with radial velocities VLG < 3500 km/s, covering the entire sky (4.8% of 10 900 galaxies in the volume).
- Catalog of isolated galaxies selected from the 2MASS survey; 2MIG.
The 2MIG catalog contains of 3227 isolated sources (6% of 2MASS Extended Sources Catalog) brighter than Ks = 12m; with angular diameters aK ≥ 30′′ .
- We also compiled the list of isolated galaxies using the second order Voronoi tesselation: Elyiv, Melnyk & Vavilova, 2009. In this work we considered SDSS galaxies within 3500<V<9500 km/s.