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R. Perna, J. Raymond, R. Narayan (Harvard-Smithsonian Center for Astrphysics)
X-ray spectral models of black holes accreting with hot accretion flows are presented, paying particular attention to thermal emission lines from the hot plasma. It is shown how detailed measurements of line profiles can strongly constrain the gas dynamics, and especially its rotation rate. Line-ratio diagnostics which are sensitive to the distribution of mass with temperature in the flow are presented, and their use to constrain the run of density with radius and the size of the hot region is emphasized. It is also shown how X-ray line diagnostics can help discriminate advection-dominated accretion flows from photoionization-dominated accretion disk coronae. Specific results are shown for the Galactic center source Sg A* and the nucleus of M87, and the possibility of observing such lines with current X-ray instruments is discussed.