Stellar Feedback & Bulge Formation in Clumpy Disks

TL;DR

This study uses numerical simulations to explore how stellar feedback influences the formation, evolution, and disruption of giant gas clumps in high-redshift galaxies, affecting bulge formation and disk evolution.

Contribution

It demonstrates that stellar feedback disrupts massive clumps, reducing bulge formation, and shows that internal disk evolution occurs even without mergers, resembling bar and spiral structures.

Findings

Stellar feedback disrupts giant clumps after 10-20% star formation.

Feedback reduces bulge formation by clump coalescence by several times.

Galactic disks evolve internally with continuous clump formation and disruption.

Abstract

We use numerical simulations of isolated galaxies to study the effects of stellar feedback on the formation and evolution of giant star-forming gas 'clumps' in high-redshift, gas-rich galaxies. Such galactic disks are unstable to the formation of bound gas-rich clumps whose properties initially depend only on global disk properties, not the microphysics of feedback. In simulations without stellar feedback, clumps turn an order-unity fraction of their mass into stars and sink to the center, forming a large bulge and kicking most of the stars out into a much more extended stellar envelope. By contrast, strong radiative stellar feedback disrupts even the most massive clumps after they turn ~10-20% of their mass into stars, in a timescale of ~10-100 Myr, ejecting some material into a super-wind and recycling the rest of the gas into the diffuse ISM. This suppresses the bulge formation rate by direct 'clump coalescence' by a factor of several. However, the galactic disks do undergo significant internal evolution in the absence of mergers: clumps form and disrupt continuously and torque gas to the galactic center. The resulting evolution is qualitatively similar to bar/spiral evolution in simulations with a more homogeneous ISM.