Morphology with Light Profile Fitting of Confirmed Cluster Galaxies at z=0.84

TL;DR

This study analyzes the morphologies of 124 confirmed cluster galaxies at z=0.84 using light profile fitting and compares their distribution across different cluster regions, revealing significant morphological evolution linked to dark matter density.

Contribution

It introduces a detailed morphological classification scheme for high-redshift cluster galaxies and compares their distribution with field galaxies and across dark matter densities.

Findings

Early-type galaxy fraction is 47%, higher than in the field.

Morphology distribution varies significantly with dark matter density.

Many galaxies may evolve directly from peculiar to early-type without becoming spirals.

Abstract

We perform a morphological study of 124 spectroscopically confirmed cluster galaxies in the z=0.84 galaxy cluster RX J0152.7-1357. Our classification scheme includes color information, visual morphology, and 1-component and 2-component light profile fitting derived from Hubble Space Telescope riz imaging. We adopt a modified version of a detailed classification scheme previously used in studies of field galaxies and found to be correlated with kinematic features of those galaxies. We compare our cluster galaxy morphologies to those of field galaxies at similar redshift. We also compare galaxy morphologies in regions of the cluster with different dark-matter density as determined by weak-lensing maps. We find an early-type fraction for the cluster population as a whole of 47%, about 2.8 times higher than the field, and similar to the dynamically young cluster MS 1054 at similar redshift. We find the most drastic change in morphology distribution between the low and intermediate dark matter density regions within the cluster, with the early type fraction doubling and the peculiar fraction dropping by nearly half. The peculiar fraction drops more drastically than the spiral fraction going from the outskirts to the intermediate-density regions. This suggests that many galaxies falling into clusters at z~0.8 may evolve directly from peculiar, merging, and compact systems into early-type galaxies, without having the chance to first evolve into a regular spiral galaxy.