Cosmological Galaxy Evolution with Superbubble Feedback I: Realistic Galaxies with Moderate Feedback

TL;DR

This paper demonstrates that superbubble feedback driven by supernovae can produce realistic cosmological galaxy simulations with properties matching observations, without extra feedback mechanisms.

Contribution

First cosmological galaxy simulation using GASOLINE2 with superbubble feedback, showing realistic galaxy properties from high redshift to present.

Findings

Galaxies have flat rotation curves (~200 km/s).

Low bulge-to-disc ratios and realistic stellar mass fractions.

Effective early gas expulsion prevents overproduction of stars.

Abstract

We present the first cosmological galaxy evolved using the modern smoothed particle hydrodynamics (SPH) code GASOLINE2 with superbubble feedback. We show that superbubble-driven galactic outflows powered by Type II supernovae alone can produce $\rm{L^*}$ galaxies with flat rotation curves with circular velocities $\sim 200\; \rm{km/s}$, low bulge-to-disc ratios, and stellar mass fractions that match observed values from high redshift to the present. These features are made possible by the high mass loadings generated by the evaporative growth of superbubbles. Outflows are driven extremely effectively at high redshift, expelling gas at early times and preventing overproduction of stars before $z=2$. Centrally concentrated gas in previous simulations has often lead to unrealistically high bulge to total ratios and strongly peaked rotation curves. We show that supernova-powered superbubbles alone can produce galaxies that agree well with observed properties without the need for additional feedback mechanisms or increased feedback energy. We present additional results arising from properly modelled hot feedback.