Starbursts: Triggers and Evolution

Why do the circumnuclear (inner 1–2 kpc) regions of spirals show vastly different star formation rates (SFR) even if they have a comparable molecular gas content? Why do some develop starbursts which are intense short-lived (t ≪ 1 Gyr) episodes of star formation characterized by a high star formation rate per unit mass of molecular gas (SFR/MH2 ), which I refer to as star formation efficiency (SFE). I address these questions using high resolution (2″ or 100–200 pc) CO (J=1→0) observations from the Owens Valley Radio Observatory, optical and NIR images, along with published radio continuum (RC) and Brγ data. The sample of eleven galaxies includes the brightest nearby starbursts comparable to M82 and control non-starbursts. More detailed results are in [8] and [10].