Devouring The Centaurus A Satellites: Modeling Dwarf Galaxies with Galacticus

TL;DR

This study uses the semi-analytic model Galacticus to simulate and analyze the properties of dwarf galaxies around Centaurus A, providing insights into their star formation and structural characteristics.

Contribution

It demonstrates that Galacticus can effectively reproduce observed properties of Centaurus A's dwarf satellites, offering a computationally feasible alternative to hydrodynamic simulations.

Findings

Reproduces luminosity functions and size-metallicity relations

Predicts star formation histories consistent with Milky Way dwarfs

Provides insights into environmental effects on dwarf galaxy properties

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 As mass (roughly ten 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 As 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 semi-analytic 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 the 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.