Examining the First Ultra-Compact Dwarf with a Resolved Extended Halo

Abstract

Ultra-compact dwarf galaxies are a class of compact galaxies and are among the densest stellar systems in the Universe (Seth et al. , 2014). Since these ultra-compact dwarfs (UCDs) have only been discovered in the last two decades, their formation is still unknown Pfeffer et al. (2014). One hypothesis for their formation, the motive behind this research, is that UCD originate as Nuclear Star Clusters (NSCs) in the central regions of low-mass galaxies, and they develop into these ultra-compact objects after gravitational interaction with a more massive galaxy (Evstigneeva et al. , 2007). In order to investigate whether or not this hypothesis is true, the first step is to determine if these UCDs have any characteristics of a NSC. The UCD that we focused on throughout this research is CenA-MM-UCD1, which lies in the halo of its host galaxy Centaurus A. CenA-MM-UCD1 was selected for further study because it is the first ultra-compact dwarf that has a resolved extended halo. This is a sign that this galaxy could be in a state of disruption from its host galaxy and, based on our hypothesis, could be transitioning from a NSC to a UCD. Throughout this study of CenA-MM-UCD1, we use images from the Hubble Space Telescope to determine if our hypothesis is true.