"Quasar feedback in structure formation"
Quasar outflows, in the form of broad-absorption line winds and radio
jets, are likely to have left an indelible cosmological imprint. As
material from the centers of galaxies made its way into the
intergalactic medium (IGM), it impacted structures on many scales, much
as supernovae impact structures on many scales within the interstellar
medium. I will outline several observational features that are likely
to have been caused by these interactions. As large regions of the IGM
are shocked heated above a critical entropy of 100 keV cm^2, cooling
becomes impossible within them, regardless of further changes in
density. On quasar scales, this results in the observed fall-off in
number densities below z = 2. On galaxy scales, quasar heating 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 then 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 seminar will be held in 544 Campbell Hall.
Return to seminar schedule