Yazar "Doenmez, O." seçeneğine göre listele

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    Dynamics of ultrarelativistic jets
    (AMER INST PHYSICS, 2007) Doenmez, O.; Kayali, R.; Cetin, SA; Hikmet, I
    We investigate the dynamics and morphology of jets propagating into the interstellar medium using 2D special relativistic hydrodynamics code. The calculations are performed assuming axisymmetric geometry and trace a long propagation of jets. The jets are assumed to be higher density than the ambient gas. The relativistic astrophysical jet is modeled for ultrarelativistic flow case. The dynamics of jet flowing is then determined by the ambient parameters such as densities, and velocities of the jets and the momentum impulse applied to the computational surface. We obtain solutions for the jet structure, propagation of jet during the time evolution, and variation in the Mach number, pressure and Lorentz factor on the computational domain at a fixed time.
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    Perturbed accretion disk around the massive black hole
    (AMER INST PHYSICS, 2007) Doenmez, O.; Cetin, SA; Hikmet, I
    In this paper, perturbations of an accretion disk by a star orbiting around a massive black hole are studied. We report on a numerical experiment, which has been carried out by using a parallel-machine code originally developed by Ref.[1]. An initially steady state accretion disk near a non-rotating (Schwarzschild) black hole interacts with a "star", modeled as an initially circular region of increased density. Part of the disk is affected by the interaction. We follow the evolution for order of one dynamical period and we show how the non-axisymetric density perturbation further evolves and moves downward where the material of the disk and the star become eventually accreted onto the central body. When the accretion disk, in steady state or not, is perturbed by star, disk around the black hole is destroyed by the star-disk interaction. Destroyed accretion disks at different locations create spiral shock waves and they causes losing its angular momentum. Finally, because of losing angular momentum, gas starts falling into the black hole. At the same time, X-ray is emitted by accretion disk during the unstable cases. The massive black hole may be created as a consequence of interaction.