The shearing sheet and swing amplification revisited
نویسندگان
چکیده
منابع مشابه
Density waves in the shearing sheet I. Swing amplification
The shearing sheet model of a galactic disk is studied anew. The theoretical description of its dynamics is based on three building blocks: Stellar orbits, which are described here in epicyclic approximation, the collisionless Boltzmann equation determining the distribution function of stars in phase space, and the Poisson equation in order to take account of the self–gravity of the disk. Using...
متن کاملDensity waves in the shearing sheet V. Feedback cycle for swing amplification by non–linear effects
Non–linear effects in the dynamical evolution of a shearing sheet made of stars are studied. First the implications of hitherto neglected non–linearities of the Boltzmann equation for the dynamical evolution of the shearing sheet are investigated. Using a formalism developed previously on the basis of the linearized Boltzmann equation it is demonstrated that the inclusion of the non–linear term...
متن کاملNonaxisymmetric stability in the shearing sheet approximation
Aims. To quantify the transient growth of nonaxisymmetric perturbations in unstratified magnetized and stratified non-magnetized rotating linear shear flows in the shearing sheet approximation of accretion disc flows. Methods. The Rayleigh quotient in modal approaches for the linearized equations (with time-dependent wavenumber) and the amplitudes from direct shearing sheet simulations using a ...
متن کاملDensity waves in the shearing sheet III. Disc heating
The problem of dynamical heating of galactic discs by spiral density waves is discussed using the shearing sheet model. The secular evolution of the disc is described quantitatively by a diffusion equation for the distribution function of stars in the space spanned by integrals of motion of the stars, in particular the radial action integral and an integral related to the angular momentum. Spec...
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Complement amplification in blood takes place not only on activating surfaces, but in plasma as well, where it is maintained primarily by C3b2-IgG complexes. Regular products of C3 activation in serum, these complexes are inherently very efficient precursors of the alternative pathway C3 convertase. Moreover, they can bind properdin bivalently, thus creating preferred sites for convertase forma...
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ژورنال
عنوان ژورنال: Monthly Notices of the Royal Astronomical Society
سال: 2020
ISSN: 0035-8711,1365-2966
DOI: 10.1093/mnras/staa1485