High-Energy Astrophysics American and Soviet Perspectives/Proceedings from the U.S.-U.S.S.R. Workshop on High-Energy Astrophysics (1991) / Chapter Skim
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MANIFESTATIONS OF DYNAMO DRIVEN LARGE-SCALE MAGNETIC FIELD IN ACCRETION DISKS OF COMPACT OBJECTS
MANIFESTATIONS OF DYNAMO DRIVEN LARGE-SCALE MAGNETIC FIELD IN ACCRETION DISKS OF COMPACT OBJECTS
Pages 46-54
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From page 46... ...
magnetic fields in the majority of astrophysical objects is determined by the turbulent dynamo action. The magnetic field generation sources in the turbulent dynamo mechanism are the differential rotation of the medium and the gyrotropic character of the turbulence, existing in this medium (Moflatt 1978; Vainstein et al.
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From page 47... ...
In particular, it is shown below that at the accretion onto the black holes, the dynamical activity of the strong toroidal, large-scale magnetic field as a result of the Parker instability development, in the disk, maximum energy release region, can create such formations (hot, optically thin coronaes3 which can explain, for example, the Cyg X-1 spectrum and radiation specifications in the low state of this source. It is also shown below that at the disk accretion of the magnetized plasma onto an aligned grav~nagnet~c rotator, the existence of two magnetic fields of different origin in the system leads to the asymmetric accretion of the matter.
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From page 48... ...
Thermal convection is also absent in the middle region if M > Mcr' and for M < MCr the parameters of the region are such that it becomes unstable against thermal convection; that is, the middle region becomes connectively active. This is the very circumstance that makes the accretion disk magnetically active and switches Cyg X-1 to the "low" state.
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From page 49... ...
We assume that magnetic flux tubes emerging in the region of the main energy release are heated, forming a hot, optically thin corona. The latter is made up of several magnetic arcs which are connected with the main disk and are sweeping inward in the process of matter accretion.
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From page 50... ...
the case where the disk has the large-scale magnetic field generated as a result of the turbulent dynamo action is realized. The field obtained thus is mainly of toroidal configuration (Chagelishvili e' al.
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From page 51... ...
Namely, the manifestation of this asymmetry is such a circumstance when the plasma accretion will take place mainly to one of the rotator magnetic poles and not to both. The accretion will be asymmetrical in the case discussed by us and that, by all means, should adequately describe the observational manifestations of such systems.
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From page 52... ...
Finally we enumerate those observational manifestations to which the above-described accretion can lead due to the asymmetry: · if such a system is capable of generating jets, Men they will be observed only in one direction; · even the slightest change of the accretion rate can lead to the RC/RA-1 sign change. That will lead to the fact that the other pole will become accreting.
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From page 53... ...
Supposing the neutron star to be a compact object, if the pressure of the electromagnetic radiation and the one of the relativistic particles ejected from the polar cap are sufficient high, then the accreting matter from the above-mentioned quasispheric component is "swept" out of the capture region or out of the light cylinder limits. Then the non-accreting magnetic pole will be an ejector, similar to the single magnetized neutron star.
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From page 54... ...
Black holed Wile Bat "d neuron saw.
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