منابع مشابه
Outflows from dynamo-active protostellar accretion discs
An axisymmetric model of a cool, dynamo-active accretion disc is applied to protostellar discs. Thermally and magnetically driven outflows develop that are not collimated within 0.1AU. In the presence of a central magnetic field from the protostar, accretion onto the protostar is highly episodic, which is in agreement with earlier work.
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Local hydromagnetic simulations of accretion-disc turbulence currently provide the most convincing evidence that the origin of turbulence in discs could be the Balbus{ Hawley magnetorotational instability. The main results of such calculations are highlighted with particular emphasis on the generation of large-scale magnetic elds. Comparison with mean- eld dynamo theory is made. This theory ...
متن کاملElectron-positron outflows from gamma-ray emitting accretion discs
An e atmosphere is inevitably created around a black hole accretion disc whose spectrum extends to MeV energies. Pairs created in γ − γ collisions outside the disc are blown away by soft radiation (which dominates the bolometric luminosity of the disc) and form a semi-relativistic outflow. We simulate numerically the conversion of the MeV radiation into a vertical e outflow above a disc-like so...
متن کاملAccretion Discs with Strong Toroidal Magnetic Fields
Simulations and analytic arguments suggest that the turbulence driven by magnetorotational instability (MRI) in accretion discs can amplify the toroidal (azimuthal) component of the magnetic field to a point at which magnetic pressure exceeds the combined gas + radiation pressure in the disc. Arguing from the recent analysis by Pessah and Psaltis, and other MRI results in the literature, we con...
متن کاملPolarization signatures of strong gravity in AGN accretion discs
The effects of strong gravity on the polarization of the Compton reflection from an X-ray illuminated accretion disc are studied. The gravitational field of a rotating black hole influences Stokes parameters of the radiation along the propagation to a distant observer. Assuming the lamp-post model, the degree and the angle of polarization are examined as functions of the observer’s inclination ...
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ژورنال
عنوان ژورنال: Astronomy & Astrophysics
سال: 2020
ISSN: 0004-6361,1432-0746
DOI: 10.1051/0004-6361/202037772