Cluster Galaxy Morphologies: The Relationship among Structural Parameters, Activity and the Environment

TL;DR

This study classifies galaxy morphologies in clusters using an ellipticity and bulge-to-total ratio approach, revealing relationships among galaxy types, brightness, and environment, and estimating black hole masses in radio galaxies.

Contribution

Introduces a calibrated morphological classification method based on ellipticity and B/T ratio, applied to 635 galaxies in clusters, linking morphology with brightness and black hole mass estimates.

Findings

Ellipticals and spirals are slightly brighter than S0 galaxies in R band.

S0 bulges are brighter than spiral bulges, suggesting ram pressure is not the main formation mechanism.

Cluster radio galaxies span S0 to E-cD types with black hole masses of 10^8-10^9 solar masses.

Abstract

We use an approach to estimate galaxy morphologies based on an ellipticity (e) vs. Bulge-to-Total ratio (B/T) plane. We have calibrated this plane by comparing with Dressler's classifications. With the aid of our calibration, we have classified 635 galaxies in 18 Abell clusters (0.02 < z < 0.08). Our approach allowed us to recover the Kormendy's relation. We found that ellipticals and Spirals are slightly brighter than S0 in R band. As S0 bulges are brighter than spirals bulges, we believe that ram pressure is not the main mechanism to generate S0s. In our sample, cluster radio galaxies morphologies cover the range S0-E-cD and their bulges have absolutes magnitudes distributed within -21 mag < M < -24.5 mag. If we believe Ferrarese & Merrit's relation, these radio sources have 10^8-10^9 M black hole mass.