Magnetohydrodynamic simulations of the collapsar model for early and late evolution of gamma-ray bursts
ثبت نشده
چکیده
I present results from magnetohydrodynamic (MHD) simulations of a gaseous envelope collapsing onto a black hole. These results support the notion that the collapsar model is one of most promising scenarios to explain the huge release of energy in a matter of seconds associated with Gamma Ray Bursts (GRB). Additionally, the MHD simulations show that at late times, when the mass supply rate is expected to decrease, the region in the vicinity of the black hole can play an important role in determining the rate of accretion, its time behaviour, and ultimately the energy output. In particular, the magnetic flux accumulated around the black hole can repeatedly stop and then restart the energy release. As proposed by Proga and Zhang, the episode or episodes of reoccurring of accretion processes can correspond to X-ray flares discovered recently in a number of GRBs.
منابع مشابه
Magnetohydrodynamic simulations of the collapsar model for early and late evolution of gamma-ray bursts.
I present results from magnetohydrodynamic (MHD) simulations of a gaseous envelope collapsing onto a black hole (BH). These results support the notion that the collapsar model is one of the most promising scenarios to explain the huge release of energy in a matter of seconds associated with gamma-ray bursts (GRBs). Additionally, the MHD simulations show that at late times, when the mass supply ...
متن کاملMHD Simulations of the Collapsar Model for GRBs
We present results from axisymmetric, time-dependent magnetohydrodynamic (MHD) simulations of the collapsar model for gamma-ray bursts. Our main conclusion is that, within the collapsar model, MHD effects alone are able to launch, accelerate and sustain a strong polar outflow. We also find that the outflow is Poynting flux-dominated, and note that this provides favorable initial conditions for ...
متن کاملAxisymmetric MHD simulations of the collapsar model for gamma-ray bursts
We present results from axisymmetric, time-dependent magnetohydrodynamic (MHD) simulations of the collapsar model for gamma-ray bursts. We begin the simulations after the 1.7 M⊙ iron core of a 25 M⊙ presupernova star has collapsed and study the ensuing accretion of the 7 M⊙ helium envelope onto the central black hole formed by the collapsed iron core. We consider a spherically symmetric progeni...
متن کاملDynamics and gravitational wave signature of collapsar formation.
We perform 3+1 general relativistic simulations of rotating core collapse in the context of the collapsar model for long gamma-ray bursts. We employ a realistic progenitor, rotation based on results of stellar evolution calculations, and a simplified equation of state. Our simulations track self-consistently collapse, bounce, the postbounce phase, black hole formation, and the subsequent early ...
متن کاملMagnetohydrodynamic Simulations of Gamma-ray Burst Jets: beyond the Progenitor Star
Achromatic breaks in afterglow light curves of gamma-ray bursts (GRBs) arise naturally when the product of the jet’s Lorentz factor γ and opening angle Θ j satisfies γΘ j ≫ 1. Magnetohydrodynamic (MHD) simulations of collimated GRB jets generally give γΘ j . 1, suggesting that MHD models are incapable of explaining jet breaks. We work within the collapsar paradigm and use axisymmetric relativis...
متن کامل