X-Ray spectra from accretion disks illuminated by protons

• Main Authors: Deufel, B, Dullemond, C. P, Spruit, H. C
• Format: Journal Article
• Language: English
• Published: 30-08-2001
• Subjects: Physics - Astrophysics of Galaxies; Physics - Cosmology and Nongalactic Astrophysics; Physics - Earth and Planetary Astrophysics; Physics - High Energy Astrophysical Phenomena; Physics - Instrumentation and Methods for Astrophysics; Physics - Solar and Stellar Astrophysics
• DOI: 10.48550/arxiv.astro-ph/0108496

The X-ray spectrum from a cool accretion disk heated by virialized protons is
computed. The cool disk is either embedded in a magnetically heated accretion
disk corona or partly extends into an ion supported torus (or ADAF). We
calculate the stationary equilibrium between proton heating, electron thermal
conduction and the radiative losses by bremsstrahlung and Compton scattering. A
heated surface layer on top of the accretion disk is produced with temperatures
between 60--90 keV above a cool layer with temperatures of 0.01 keV (AGN) and
1keV (galactic black hole candidates). The spectra produced by the surface
layer are reminiscent of hard state spectra, but a bit too steep, especially
for AGN's. Near the inner edge of the disk, where the optical depth of the disk
$\tau lesssim 1$, we find that the cool component of the disk disappears.
Instead, the hot protons from the corona/ADAF heat the disk, on a dynamical
time-scale, to temperatures of several 100 keV, limited by pair production.
This region, here called a `warm disk', could contribute significantly to the
hard X-ray spectra and could be important for feeding material into an ADAF.