Segregation Effects According to the Evolutionary Stage of Galaxy Groups

TL;DR

This study investigates how galaxy segregation varies with the evolutionary stage of galaxy groups, revealing that more relaxed groups contain more evolved, redder galaxies and show signs of energy equipartition.

Contribution

It provides the first detailed analysis linking galaxy segregation phenomena to the dynamical state of galaxy groups based on velocity distribution analysis.

Findings

Galaxies in Gaussian groups are more evolved and redder than in non-relaxed groups.

Galaxies with M_R < -21.5 in Gaussian groups approach energy equipartition.

84% of groups have velocity distributions consistent with relaxation.

Abstract

We study segregation phenomena in 57 groups selected from the 2PIGG catalog of galaxy groups. The sample corresponds to those systems located in areas of at least 80% redshift coverage out to 10 times the radius of the groups. The dynamical state of the galaxy systems was determined after studying their velocity distributions. We have used the Anderson-Darling test to distinguish relaxed and non-relaxed systems. This analysis indicates that 84% of groups have galaxy velocities consistent with the normal distribution, while 16% of them have more complex underlying distributions. Properties of the member galaxies are investigated taking into account this classification. Our results indicate that galaxies in Gaussian groups are significantly more evolved than galaxies in non-relaxed systems out to distances of about 4R200, presenting signficantly redder (B-R) color. We also find evidence that galaxies with M_R < -21.5 in Gaussian groups are closer to the condition of energy equipartition.