DR. SUSMITA CHAKRAVORTY

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.