AGN/XRB warm absorbers: a key to their broader phenomenology |
| TYPE | Astrophysics Seminar |
| Speaker: | Demos Kazanas |
| Affiliation: | NASA |
| Date: | 24.05.2017 |
| Time: | 14:30 - 15:30 |
| Location: | Lidow 620 |
| Abstract: | An increasing number of observations have indicated the presence of blue shifted absorption features in the X-ray spectra of both AGN and accreting galactic X-ray binaries that span a large range in ionization parameter and velocity. These have been attributed and successfully modeled by accretion disk winds. Moreover, the dependence of their column density on their ionization parameter has allowed to determine the wind density profile along the observer's LoS and hence the corresponding wind mass flux. This was found to be an increasing function of the distance from the X-ray source, with the corresponding mass flux much larger than that needed to produce, by accretion, the observed X-ray luminosity. This signifies that the disk accretion rate decreases with radius, much of is mass flux diverted into the wind. This decreasing accretion rate in the disk, then, makes it possible for its inner regions to revert to a hot, X-ray emitting ADAF state, while its cooler, BBB component to be emitted at larger radii, despite the fact that it is more luminous, in agreement with microlensing observations. It will be argued that an increase in the overall supply of matter to the black hole can under these assumptions reproduce much of the global spectral AGN/XRB phenomenology, in particular the AGN $\alpha_{OX}$ dependence on luminosity and their warm absorber properties. |