Original sentence: One implication is that a quasar would not, for example, continue to feed at that rate for 10 billion years, which nicely explains why there aren't nearby quasars.One of the most widely-excepted explanations for quasars is that they are powered by supermassive black holes.Quasars may also provide some clues as to the end of the Big Bang's reionization.Since quasars exhibit properties common to all active galaxies, many scientists have compared the emissions from quasars to those of small active galaxies due to their similarity to each other.The oldest quasars (z > 4) display a Gunn-Peterson trough and appear to have absorption regions in front of them indicating that the intergalactic medium at that time was neutral gas.This is thoughtSuperscript text to mean that galaxies underwent a massive phase of star formation creating population III stars between the time of the Big Bang and the first observed quasars
Edited sentence: One implication is that a quasar would not, for example, continue to feed at that rate for 10 billion years, which nicely explains why there are no nearby quasars.Quasars also provide some clues as to the end of the Big Bang's reionization.Since quasars exhibit properties common to all active galaxies, many scientists have compared the emissions from quasars to those of small active galaxies due to their similarity.The best explanation for quasars is that they are powered by supermassive black holes.The oldest quasars (z > 4) display a Gunn-Peterson trough and clearly have absorption regions in front of them indicating that the intergalactic medium at that time was neutral gas.This is taken to mean that galaxies underwent a massive phase of star formation creating population III stars between the time of the Big Bang and the first observed quasars