Devouring the Centaurus A Satellites: Modeling Dwarf Galaxies with Galacticus

Abstract

For the first time, systematic studies of dwarf galaxies are being conducted throughout the Local Volume, including the dwarf satellites of the nearby giant elliptical galaxy Centaurus A (NGC 5128). Given Centaurus A's mass (roughly 10 times larger than that of the Milky Way), AGN activity, and recent major mergers, investigating the dwarf galaxies of Centaurus A and their star formation physics is imperative. However, simulating the faintest dwarfs around a galaxy of Centaurus A's mass with sufficient resolution in a hydrodynamic simulation is computationally expensive and currently infeasible. In this study, we seek to reproduce the properties of Centaurus A dwarfs using the semianalytic model Galacticus to model dwarfs within a 700 kpc region around Centaurus A, corresponding approximately to its splashback radius. We investigate the effects of host halo mass and environment and predict observable properties of Centaurus A dwarfs using astrophysical prescriptions and parameters previously tuned to match properties of the Milky Way’s satellite galaxies. This approach allows us to approximately replicate cumulative luminosity functions, and luminosity–metallicity and luminosity–half-light-radii relations observed in the Centaurus A satellites. We provide predictions for the velocity dispersions, and star formation histories of Centaurus A dwarfs. The agreement between our predicted star formation histories for Centaurus A dwarfs and those of the Milky Way dwarfs implies the presence of universal processes governing star formation in dwarf galaxies. Overall, our findings shed light on the star formation physics of dwarf galaxies in the Centaurus A system, revealing insights into their properties and dependence on the host environment.