Simulating the Milky Way bar and bulge with an initially S\'{e}rsic disc

TL;DR

This study uses simulations of a Milky Way-like galaxy with an initial Sersic disc and gas component to demonstrate that a bar and bulge can form and evolve naturally without a classical bulge, matching observed properties.

Contribution

It introduces a simulation model with an initial Sersic disc and gas component that reproduces the Milky Way's bar and bulge features without requiring a classical bulge.

Findings

The simulated bar matches the size and pattern speed of the Milky Way.

The model reproduces the box/peanut shape of the bulge.

A Sersic index of 1.75 and 7% gas mass yield realistic galaxy features.

Abstract

We model the formation of a bar plus box/peanut bulge (BP bulge) component in a Milky Way-like disc galaxy using simulations of isolated multi-component systems that evolve from equilibrium initial conditions. The simulations are designed to test the hypothesis that the bar forms early on and thickens to create the bulge. To this end, our initial conditions include a stellar disc with a S\'{e}rsic surface density profile and do not include any classical bulge component. We also include a gas disc, which is important in regulating the growth of the bar. Our best-fit model has an initial stellar disc with a S\'{e}rsic index of $n = 1.75$ and a gas disc with mass equal to 7% of the mass of the stellar disc. The model reproduces the bar size, pattern speed, and box/peanut shape of the Milky Way's bulge+bar.