Star formation in galaxy mergers: Ism turbulence, dense gas excess, and scaling relations for disks and starbusts

Frederic Bournaud, Leila C. Powell, Damien Chapon, Romain Teyssier

Research output: Chapter in Book/Report/Conference proceedingConference contribution

8 Scopus citations


Galaxy interactions and mergers play a significant, but still debated and poorly understood role in the star formation history of galaxies. Numerical and theoretical models cannot yet explain the main properties of merger-induced starbursts, including their intensity and their spatial extent. Usually, the mechanism invoked in merger-induced starbursts is a global inflow of gas towards the central kpc, resulting in a nuclear starburst. We show here, using high-resolution AMR simulations and comparing to observations of the gas component in mergers, that the triggering of starbursts also results from increased ISM turbulence and velocity dispersions in interacting systems. This forms cold gas that are denser and more massive than in quiescent disk galaxies. The fraction of dense cold gas largely increases, modifying the global density distribution of these systems, and efficient star formation results. Because the starbursting activity is not just from a global compacting of the gas to higher average surface densities, but also from higher turbulence and fragmentation into massive and dense clouds, merging systems can enter a different regime of star formation compared to quiescent disk galaxies. This is in quantitative agreement with recent observations suggesting that disk galaxies and starbursting systems are not the low-activity end and high-activity end of a single regime, but actually follow different scaling relations for their star formation.

Original languageEnglish (US)
Title of host publicationAstrophysical Dynamics
Subtitle of host publicationFrom Stars to Galaxies
EditorsNicholas Brummell, Sacha Brun, Mark Boulder, Yannick Ponty
Number of pages10
StatePublished - Jun 2010
Externally publishedYes

Publication series

NameProceedings of the International Astronomical Union
ISSN (Print)1743-9213
ISSN (Electronic)1743-9221

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Galaxies : star formation
  • Galaxies: formation
  • Galaxies: mergers


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