Balance among gravitational instability, star formation and accretion determines the structure and evolution of disc galaxies

John C. Forbes*, Mark R. Krumholz, Andreas Burkert, Avishai Dekel

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

120 Scopus citations

Abstract

Over the past 10 Gyr, star-forming galaxies have changed dramatically, from clumpy and gas rich, to rather quiescent stellar-dominated discs with specific star formation rates lower by factors of a few tens.We present a general theoretical model for how this transition occurs, and what physical processes drive it, making use of 1D axisymmetric thin disc simulations with an improved version of the Gravitational Instability-Dominated Galaxy Evolution Tool (GIDGET) code. We show that at every radius galaxies tend to be in a slowly evolving equilibrium state wherein new accretion is balanced by star formation, galactic winds and radial transport of gas through the disc by gravitational instability-driven torques. The gas surface density profile is determined by which of these terms are in balance at a given radius - direct accretion is balanced by star formation and galactic winds near galactic centres, and by transport at larger radii. We predict that galaxies undergo a smooth transition from a violent disc instability phase to secular evolution. This model provides a natural explanation for the high velocity dispersions and large clumps in z ~ 2 galaxies, the growth and subsequent quenching of bulges, and features of the neutral gas profiles of local spiral galaxies.

Original languageEnglish
Pages (from-to)1552-1576
Number of pages25
JournalMonthly Notices of the Royal Astronomical Society
Volume438
Issue number2
DOIs
StatePublished - Mar 2014

Keywords

  • Galaxies: evolution
  • Galaxies: ISM
  • Galaxies: kinematics and dynamics
  • Galaxies: structure

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