AGN Outflows and the Matter Power Spectrum
  We have investigated the effects of AGN outflows on the amplitude of the matter power spectrum in a simple model of spherically symmetric outflows around realistically clustered AGN population. We find that two competing effects influence the matter power spectrum in two opposite directions. First, AGN outflows move baryons from high to low density regions, decreasing the amplitude of the matter power spectrum by up to 20%. Second, high clustering of the AGN transfers the power from small to larger scales. The exact balance between these two effects depends on the details of outflows on small scales, and quantitative estimates will require much more sophisticated modeling than presented here. 
Robyn Levine and Nickolay Y. Gnedin