eng URI http://hdl.handle.net/10795/2958 αστρονομία ιοντίζουσα ακτινοβολία ηλεκτρομαγνητική όχληση We investigate the characteristics of a relativistic magnetized fluid flowing around a corner. If the outflow is faster than the fast-magnetosonic speed (or sound speed for a non-magnetized fluid) the non-smooth boundary induces a rarefaction wave propagating in the body of the flow. The subsequent expansion is accompanied with a very efficient increase of the flow bulk speed and Lorentz factor. We apply this “rarefaction acceleration mechanism” to the Collapsar model of gamma-ray bursts, in which a relativistic jet initially propagates in the interior of the progenitor star, before crossing the stellar surface with a simultaneous drop in the external pressure support. We integrated the steady-state equations using a special set of partial solutions, called r – self similar. The use of these solutions degrades the system of the complex, non-linear, 2nd order partial differential equations into a system of two 1st order ordinary differential equations whose integration is straightforward. For the conditions expected in a GRB, a fully analytical solution can also be obtained. The aim of this work is to give insight to the results of recent time-depended numerical simulations and show that rarefaction is a plausible mechanism for these phenomena. 7 pp. LOMv1.0 creator LOMv1.0 publisher LOMv1.0 Scientific Coordinator LOMv1.0 Project Executing Organisation 2011 Digital Library of the Operational Programme "Education and Lifelong Learning" abstract types Text Magnetized fluid Relativistic steady Rarefaction waves Magnetized flows Gamma-ray burst http://pos.sissa.it/archive/conferences/123/041/Texas%202010_041.pdf 352064 application/pdf http://repository.edulll.gr/edulll/bitstream/10795/2958/2/2958_1.5_%ce%94%ce%97%ce%9c_6_12_11.pdf In: 5th Texas Symposium on Relativistic Astrophysics URI http://hdl.handle.net/10795/2958 LOMv1.0creator 2016-04-27T08:58:16Z LOMv1.0validator 2016-04-27T08:58:16Z LOMv1.0 gre no no Copyright EYD-EPEDBM (Operational Programme "Education and Lifelong Learning")