Search results for "methods : numerical"

showing 3 items of 3 documents

Deceleration of arbitrarily magnetized GRB ejecta: the complete evolution

2008

(Abridged) We aim to quantitatively understand the dynamical effect and observational signatures of magnetization of the GRB ejecta on the onset of the afterglow. We perform ultrahigh-resolution one-dimensional relativistic MHD simulations of the interaction of a radially expanding, magnetized ejecta with the interstellar medium. The need of ultrahigh numerical resolution derives from the extreme jump conditions in the region of interaction between the ejecta and the circumburst medium. We study the evolution of an ultrarelativistic shell all the way to a the self-similar asymptotic phase. Our simulations show that the complete evolution can be characterized in terms of two parameters, name…

Magnetohydrodynamics (MHD)Astrophysics::High Energy Astrophysical PhenomenaFOS: Physical sciencesAstrophysicsAstrophysicsUNESCO::ASTRONOMÍA Y ASTROFÍSICAShock wavesMagnetizationsymbols.namesakeGamma rays : bursts; Methods : numerical; Magnetohydrodynamics (MHD); Shock wavesUNESCO::ASTRONOMÍA Y ASTROFÍSICA::Otras especialidades astronómicasEjectaAstrophysics::Galaxy AstrophysicsPhysicsnumerical [Methods]Magnetic energyAstrophysics (astro-ph)Astronomy and AstrophysicsAfterglowInterstellar mediumLorentz factorbursts [Gamma rays]Space and Planetary SciencesymbolsMagnetohydrodynamicsGamma-ray burst:ASTRONOMÍA Y ASTROFÍSICA [UNESCO]:ASTRONOMÍA Y ASTROFÍSICA::Otras especialidades astronómicas [UNESCO]
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A new general relativistic magnetohydrodynamics code for dynamical spacetimes

2008

We present a new numerical code which solves the general relativistic magneto-hydrodynamics (GRMHD) equations coupled to the Einstein equations for the evolution of a dynamical spacetime within the conformally-flat approximation. This code has been developed with the main objective of studying astrophysical scenarios in which both, high magnetic fields and strong gravitational fields appear, such as the magneto-rotational collapse of stellar cores, the collapsar model of GRBs, and the evolution of neutron stars. The code is based on an existing and thoroughly tested purely hydrodynamics code and on its extension to accommodate weakly magnetized fluids (passive magnetic field approximation).…

Magnetohydrodynamics (MHD)Astrophysics::High Energy Astrophysical PhenomenaFOS: Physical sciencesConformal mapAstrophysicsGeneral Relativity and Quantum Cosmology (gr-qc)AstrophysicsGeneral Relativity and Quantum CosmologyRelativityGravitational fieldUNESCO::ASTRONOMÍA Y ASTROFÍSICA::Cosmología y cosmogonia::GravitaciónPhysicsnumerical [Methods]SpacetimeSolenoidal vector fieldGravitation; Hydrodynamics; Magnetohydrodynamics (MHD); Methods : numerical; Relativity; Stars : supernovae : generalsupernovae : general [Stars]Astrophysics (astro-ph)Astronomy and Astrophysics:ASTRONOMÍA Y ASTROFÍSICA::Cosmología y cosmogonia::Gravitación [UNESCO]Magnetic fieldNeutron starClassical mechanicsSpace and Planetary ScienceHydrodynamicsCircular symmetryMagnetohydrodynamicsUNESCO::ASTRONOMÍA Y ASTROFÍSICA::Cosmología y cosmogonia::EstrellasGravitation:ASTRONOMÍA Y ASTROFÍSICA::Cosmología y cosmogonia::Estrellas [UNESCO]
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Rotational effects on the oscillation frequencies of newly born proto-neutron stars

2003

In this paper we study the effects of rotation on the frequencies of the quasi-normal modes of a proto-neutron star (PNS) born in a gravitational collapse during the first minute of life. Our analysis starts a few tenths of seconds after the PNS formation, when the stellar evolution can be described by a sequence of equilibrium configurations. We use the evolutionary models developed by Pons et al. (1999; 2001) that describe how a non rotating star cools down and contracts while neutrino diffusion and thermalization processes dominate the stellar dynamics. For assigned values of the evolution time, we set the star into slow rotation and integrate the equations of stellar perturbations in th…

relativityFOS: Physical sciencesmethods : numericalAstrophysicsAstrophysicsInstabilitystars : oscillationsmethods: numericalstars: neutronstars: rotationstars : rotationStellar dynamicsGravitational collapseAstrophysics::Solar and Stellar AstrophysicsTime domainStellar evolutionPhysicsgravitational waves; methods : numerical; methods: numerical; relativity; stars : neutron; stars : oscillations; stars : rotation; stars: neutron; stars: oscillations; stars: rotationAstrophysics (astro-ph)Astronomy and Astrophysicsstars : neutronNeutron stargravitational wavesSpace and Planetary ScienceFrequency domainstars: oscillationsAstrophysics::Earth and Planetary AstrophysicsNeutrinoMonthly Notices of the Royal Astronomical Society
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