Dwarfmology

We address two important cosmological questions relating to dwarf galaxies: (1) What is their contribution to the field galaxy baryon budget; and (2) what is their contribution to the faint blue galaxy problem. Both of these are addressed empirically from a complete photometric redshift catalogue derived from the Hubble Deep Field. The answer to the first question is: very little (<1%), and to the second: a small but non-negligible amount (10% at b = 24 mags rising to 30% at b = 28 mags). Hence the cosmological significance of dwarf galaxies, from a purely baryon-centric perspective, lies in their contribution to the formation and assembly phase of the giant galaxies - where perhaps they did once dominate the baryon budget.