The effects of X-rays from an active galactic nucleus on the interstellar medium of the host galaxy

The influence of X-ray heating on the evolution and eventual structure of the ISM in a luminous active galaxy is studied. The conditions for runaway X-ray heating are outlined, and the appropriate heating rates for X-ray heated winds are estimated. The parameters which govern these winds from active spiral galaxies are discussed. The theory of Compton-heated winds by Begelman, McKee, and Shields (1983) is used to derive steady-state mass loss rates from opaque, irradiated disks in the gravitational potentials of typical spirals. These rates are compared with the accretion rates necessary to power the activity in the nucleus and with the rate at which mass can be replenished by stellar evolutionary processes in the disk. The time required to establish this steady state is estimated, and the evolution of an ISM similar to that of the Galaxy after a luminous quasar or Seyfert turns it on is described.