New g'r'i'z' Photometry of the NGC 5128 Globular Cluster System

TL;DR

This paper provides new $g'r'i'z'$ photometry for 323 globular clusters in NGC 5128, calibrates color indices to standard stars, and relates colors to metallicity, enhancing understanding of the cluster system.

Contribution

First-time $g'r'i'z'$ photometry for a large sample of NGC 5128 globular clusters with calibrated color-metallicity relations.

Findings

Established fiducial mean colors for blue and red globular clusters.

Calibrated color indices to standard stars in the $g'r'i'z'$ system.

Derived metallicity estimates from color indices.

Abstract

We present new photometry for 323 of the globular clusters in NGC 5128 (Centaurus A), measured for the first time in the $g'r'i'z'$ filter system. The color indices are calibrated directly to standard stars in the $g'r'i'z'$ system and are used to establish the fiducial mean colors for the blue and red (low and high metallicity) globular cluster sequences. We also use spectroscopically measured abundances to establish the conversion between the most metallicity-sensitive colors ($(g'-r')_0$, $(g'-i')_0$) and metallicity, [Fe/H].