Reflected quasar light powers giant cool gas nebulae 

Recent observations have revealed that the first quasars are often surrounded by bright, giant nebulae. These span up to several 100,000 light years, about ten times larger than the quasar host galaxy. According to new detailed computer simulations of galaxy evolution performed at MPA, the observed extended nebulae can be explained as quasar light that reflects off surrounding cool neutral hydrogen clouds. Crucially, this mechanism only works if the energy provided by the quasar is able to produce gigantic galactic winds that blow out large masses of gas from its immediate vicinity.