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We consider the impact of quasar outflows on structure formation. As quasars are powered by supermassive black holes, whose masses scale roughly with the depth of the potential well of their host galaxies (MBH \ Mgalaxy⁵/3), they dominate over starbursts (Eₛtarburst \ Mgalaxy) in powering outflows from the large galaxies that form at low redshifts. Using a simple analytical model for the quasar distribution, coupled with a one-dimensional Sedov-Taylor model, we are able to make robust statements as to the impact of these outflows on structure formation. As large regions of the intergalactic medium (IGM) are heated above a critical entropy of approximately 100 keV cm², cooling become impossible within them, regardless of changes in density. On quasar scales, this has the effect of inhibiting further formation, resulting in their observed fall-off in number densities below z ~ 2. On galaxy scales, quasar feedback fixes the turn-over scale in the galaxy luminosity function (L_*) as the nonlinear scale at the redshift of strong feedback. The galaxy luminosity function remains largely fixed after this epoch, consistent with recent observations and in contrast to the strong evolution predicted in more standard galaxy-formation models. Finally, strong quasar feedback explains why the intracluster medium is observed to have been pre-heated to entropy levels just above the minimum excess that would not have been erased by cooling. The presence of such outflows is consistent with the observed properties of the Lyman-alpha forest at z ~ 2, but is expected to have a substantial and detectable impact on Compton distortions observed in the microwave background and the multiphase properties of the ``warm-hot'' (z=0) circumgalactic medium.
Scannapieco et al. (Mon,) studied this question.