Published online by Cambridge University Press: 12 April 2016
Here we describe results of our attempt to determine what types of galaxies are responsible for the Lyα forest absorption systems, based on our ongoing imaging and spectroscopic survey of faint galaxies in fields of HST spectroscopic target QSOs. Our primary conclusions are that the bulk of the Lyα forest arises in more or less normal galaxies (that span the normal range of luminosity and morphology) and that any “unseen” low surface brightness galaxies are unlikely to contribute significantly to the luminosity density of the universe.