Isolated Galaxies and Isolated Satellite Systems

TL;DR

This paper develops a new method to identify isolated galaxies using SDSS data, confirming morphology conformity and emphasizing the role of hydrodynamic interactions in galaxy evolution.

Contribution

It introduces a diagnostic tool based on projected separation and local density to select isolated galaxies, enhancing understanding of galaxy environment effects.

Findings

Isolation criteria effectively segregate isolated galaxies.

Morphology conformity observed between hosts and satellites.

Hydrodynamic interactions are significant within virial radii.

Abstract

We search for isolated galaxies using a volume-limited sample of galaxies with 0.02< z < 0.04742 from SDSS DR7 supplemented by bright galaxies. We devise a diagnostic tool to select isolated galaxies in different environments using the projected separation (r_p) normalized by the virial radius of the nearest neighbor (r_{vir,nei}) and the local background density. We find that the isolation condition of r_p>r_{vir,nei} and \rho <\bar{\rho} well segregates the CIG galaxies. We confirm the morphology conformity between the host and their satellites, which suggests importance of hydrodynamic interaction among galaxies within their virial radii in galaxy evolution.