In the past decade, supercomputer simulations of galaxy formation have become so sophisticated that they can actually predict how galaxies form and are fed: gas funnels onto galaxies along thin «cold streams» which, like streams of snow melt feeding a mountain lake, channel cool gas from the surrounding intergalactic medium onto galaxies, continuously topping up their supplies of raw material for star formation. (keckobservatory.org)
The Epoch of Reionization (EOR) refers to the period in the history of the universe during which the predominantly neutral intergalactic medium was ionized by the emergence of the first luminous sources. (haystack.mit.edu)
Their gas and dust may been blown away by the galaxy moving quickly through the low - density intergalactic medium (hot, very thin gas between the galaxies) or used up in a rapid burst of star formation. (astronomynotes.com)