Thermodynamic stability for AGN and XRB winds

Thermodynamic stability is an important notion to understand the
properties of photoionized gas and predict allowed (and hence observable)
ranges of ionization states of the gas. This range is a function of the
ionizing continuum seen by the outflowing gas. We use this thermodynamic
prescription to highlight the importance of individual components, like
the radiation from the accretion disk and soft excess, in shaping the
physical properties of the AGN winds. We apply our physical insights to
understand the high resolution HST and Chandra HETGS spectra of the quasar
IRAS13349+2438. We further extend the same stability analysis to winds in
X-ray binaries. We attempt to explain the observed phenomenon that winds
are present in certain states of the binary and absent in others.