Supernovae and the Formation of Galaxies

Abstract

During this conference on supernovae there has been a progression of subject matter treated with the focus gradually shifting from the deep interior of a collapsing star (~ 10⁶ cm) to the matter seen during observed outbursts (~ 10¹³ cm) to the effect of an explosive blastwave propagating through the interstellar medium (~ 10²⁰ cm). I would like to follow the progression further, considering the cumulative effect of many supernovae in a galaxy, particularly a young galaxy, and the effect of the blastwave, formed by the combination of all individual supernova, on the intergalactic medium (IGM). I will contend that the IGM can be shock heated by this process and that in late stages of an individual expanding galaxy shock a dense shell can form with mass many times greater than the mass of the seed galaxy. This shell may fragment due to gravitational instability and give rise to a new generation of galaxies. Supernovae explosions thus may provide a hydrodynamic amplifier important in the process of galaxy formation.