# The Gemini/HST Cluster Project: Structural and Photometric Properties of Galaxies in Three z =0.28-0.89 Clusters

## TL;DR

This study analyzes galaxy structural and photometric properties in three galaxy clusters at redshifts 0.28 to 0.89, using surface brightness profile fitting to understand galaxy evolution and assess uncertainties in derived parameters.

## Contribution

It introduces a detailed methodology for deriving galaxy parameters and evaluates the impact of profile assumptions on fundamental plane measurements at intermediate redshifts.

## Key findings

- Fitting Sersic index n<4 galaxies with r^{1/4} law overestimates radius and flux.
- Uncertainties in fundamental plane parameters are small despite profile fitting differences.
- Systematic errors in magnitude and size are negligible for the analysis.

## Abstract

We present the data processing and analysis techniques we are using to determine structural and photometric properties of galaxies in our Gemini/HST Galaxy Cluster Project sample. The goal of this study is to understand cluster galaxy evolution in terms of scaling relations and structural properties of cluster galaxies at redshifts 0.15 < z < 1.0. To derive parameters such as total magnitude, half-light radius, effective surface brightness, and Sersic n, we fit r^{1/4} law and Sersic function 2-D surface brightness profiles to each of the galaxies in our sample. Using simulated galaxies, we test how the assumed profile affects the derived parameters and how the uncertainties affect our Fundamental Plane results. We find that while fitting galaxies which have Sersic index n < 4 with r^{1/4} law profiles systematically overestimates the galaxy radius and flux, the combination of profile parameters that enter the Fundamental Plane has uncertainties that are small. Average systematic offsets and associated random uncertainties in magnitude and log r_e for n > 2 galaxies fitted with r^{1/4} law profiles are -0.1+-0.3 and 0.1+-0.2 respectively. The combination of effective radius and surface brightness, log r_e - \beta log <I>_e, that enters the Fundamental Plane produces offsets smaller than -0.02+-0.10. This systematic error is insignificant and independent of galaxy magnitude or size. A catalog of photometry and surface brightness profile parameters is presented for three of the clusters in our sample, RX J0142.0+2131, RX J0152.7-1357, and RX J1226.9+3332 at redshifts 0.28, 0.83, and 0.89 respectively.