A Moderate Cooling Flow Phase at Galaxy Formation
  I study the possibility that a cooling flow (CF) exists at the main phase of
super massive black hole (SMBH) growth during galaxy formation. To ensure that
jets launched by the SMBH efficiently expel gas from the galaxy, as is required
by recent results, the gas should be in the hot phase, rather than in cold
clouds. The short radiative cooling time of the hot gas leads to the formation
of a CF, but heating by the active galactic nucleus (AGN) prevents catastrophic
cooling. Cold blobs that start as instabilities in the hot phase feed the SMBH
from an extended region, form an accretion disk, and lead to the formation of
jets. These jets can expel large quantities of gas out of the galaxy. This
cycle, that is termed cold feedback mechanism in CFs in clusters of galaxies,
might explain the correlation of SMBH to bulge masses. Stars are formed, but at
a lower rate than what is expected when heating is not included. Such a CF is
termed a moderate CF.
