Small galaxies may lie in cooler environments because they may not have heated their surrounding regions of gas to the same extent that the big galaxies did through supernova explosions and quasar energy.

• 小星系或许处在较冷的环境中，因为它们可能无法像大星系一般，透过超新星爆炸与类星体释放的能量，将其附近区域的气体加热到那麽高温。