Invited lecture at Evry Schatzman School 2010: Star Formation in the Local Universe.
astro-ph/1106.1793

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STAR FORMATION IN GALAXY INTERACTIONS AND MERGERS

Frederic Bournaud


CEA Saclay, IRFU, SAp, F-91191 Gif-sur-Yvette, France


Abstract: This lecture reviews fundamental physical processes on star formation in galaxy interactions and mergers. Interactions and mergers often drive intense starbursts, but the link between interstellar gas physics, large scale interactions, and active star formation is complex and not fully understood yet. We show that two processes can drive starbursts: radial inflows of gas can fuel nuclear starbursts, triggered gas turbulence and fragmentation can drive more extended starbursts in massive star clusters with high fractions of dense gas. Both modes are certainly required to account for the observed properties of starbursting mergers. A particular consequence is that star formation scaling laws are not universal, but vary from quiescent disks to starbursting mergers. High-resolution hydrodynamic simulations are used to illustrate the lectures.


Table of Contents

INTRODUCTION

GALAXY-SCALED STAR FORMATION AND ISM DYNAMICS - BASIC FACTS
Disk stability and star formation
The heterogeneous and turbulent ISM
Star formation in the turbulent ISM

DYNAMICS OF GALAXY INTERACTIONS AND MERGERS
Dynamical Friction
Violent Relaxation
Gas response and tidal torques

STAR FORMATION TRIGGERING IN INTERACTIONS - FROM MERGERS TO STARBURSTS
Main observed facts
Standard theory of merger-induced starbursts: gas inflows and nuclear starbursts
Limitations of the standard theory
Star formation in mergers: effect of the turbulent, cloudy ISM
From triggered turbulence to dense gas excess and starbursts
Implications for star formation "laws"
Summary

STRUCTURE FORMATION IN MERGERS, SUPER STAR CLUSTERS AND GLOBULAR CLUSTERS

CONCLUSION AND IMPLICATIONS FOR GALAXY FORMATION

REFERENCES

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