Stellar Feedback & Bulge Formation in Clumpy Disks
  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.
