To appear in "Starbursts: From 30 Doradus to Lyman-Break
Galaxies," eds. R. de Grijs & R.M. Gonzalez Delgado (Kluwer, Dordrecht),
2005.
astro-ph/0502111
For a PDF version of the article, click
here.
MERGER-INDUCED STARBURSTS
Francois Schweizer
Carnegie Observatories,
Pasadena, CA 91101, USA
Abstract.
Extragalactic starbursts induced by gravitational interactions can now be
studied from z 
0 to 
2. The evidence
that mergers of
gas-rich galaxies tend to trigger galaxy-wide starbursts is strong, both
statistically and in individual cases of major disk-disk mergers.
Star formation rates appear enhanced by factors of a few to ~ 103
above normal. Detailed studies of nearby mergers and ULIRGs suggest that
the main trigger for starbursts is the rapidly mounting pressure of the
ISM in extended shock regions, rather than high-velocity, 50-100
km s-1 cloud-cloud collisions. Numerical simulations demonstrate
that in colliding galaxies the
star formation rate depends not only on the gas density,
but crucially also on energy dissipation in shocks. An often overlooked
characteristic of merger-induced starbursts is that the spatial
distribution of the enhanced star formation extends over large scales
(~ 10-20 kpc). Thus, although most such starbursts do peak
near the galactic centers, young stellar populations pervade merger
remnants and explain why (1) age gradients in descendent galaxies are mild
and (2) resultant cluster systems are far-flung. This review presents
an overview of interesting phenomena observed in galaxy-wide starbursts
and emphasizes that such events continue to accompany the birth of
elliptical galaxies to the present epoch.
Table of Contents
