Tomography of accretion flows in binary stars and active galactic nuclei

Astrotomography resolves accretion flows with micro-arcsecond angular resolution. Eclipses by a binary companion star slice up a disk surface, giving monochromatic maps of the disk, or spectra from any region of its surface. Doppler tomography maps emission-line regions from the changing velocity profile as the binary rotates, revealing radial and azimuthal structure, gas streams, irradiated companion stars, magnetic flows, and slingshot prominences. Echo mapping exploits time delays between the hard radiation from near the compact object at the focus of the flow, and softer emission generated by irradiation of regions farther out. The maximum entropy techniques for fitting intensity maps to data are currently being extended by incorporating local physics and mapping physical parameters such as temperature, density, surface density, and velocity dispersion.