منابع مشابه
Outbursts of Irradiated Accretion Discs
I solve analytically the viscous evolution of a self–irradiated accretion disc, as seen during outbursts of soft X–ray transients. The solutions predict steep power–law X– ray decays LX ∼ (1 + t/tvisc) , changing to LX ∼ (1 − t/t ′ visc ) at late times, where tvisc, t ′ visc are viscous timescales. These forms closely resemble the approximate exponential and linear decays inferred by King and R...
متن کاملThe behaviour of quiescent accretion discs in dwarf novae
We propose a simple explanation for the constant mean brightness observed between outbursts in dwarf novae. Secular changes in the total energy dissipation rate of the accretion disc brought about by variations in surface density, temperature and disc radius can be regulated by the gradual cooling of a small, critically-stable hot inner region. The hypothesis is supported with two-dimensional t...
متن کاملIonization structure and Fe Kα energy for irradiated accretion discs
We study the radial ionization structure at the surface of an X-ray illuminated accretion disc. We plot the expected iron Kα line energy as a function of the Eddington ratio and of the distance of the emitting matter from the central source, for a non-rotating and a maximally rotating black hole. We compare the predicted disc line energies with those measured in an archival sample of active gal...
متن کاملModelling magnetised accretion discs
Some recent results are reviewed that lead us now to believe that accretion discs are basically always magnetised. The main components are Balbus-Hawley and Parker instabilities on the one hand and a dynamo process on the other. A mechanical model for the Balbus-Hawley instability is presented and analysed quantitatively. Three-dimensional simulations are discussed, especially the resulting mag...
متن کاملSelf-gravitating accretion discs
— I review recent progresses in the dynamics and the evolution of self-gravitating accretion discs. Accretion discs are a fundamental component of several astrophysical systems on very diverse scales, and can be found around supermassive black holes in Active Galactic Nuclei (AGN), and also in our Galaxy around stellar mass compact objects and around young stars. Notwithstanding the specific di...
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ژورنال
عنوان ژورنال: Astronomy & Astrophysics
سال: 2001
ISSN: 0004-6361,1432-0746
DOI: 10.1051/0004-6361:20010910