Academic Journal
Deceleration of arbitrarily magnetized GRB ejecta: the complete evolution
| العنوان: | Deceleration of arbitrarily magnetized GRB ejecta: the complete evolution |
|---|---|
| المؤلفون: | P. Mimica, D. Giannios, M. A. Aloy |
| المساهمون: | The Pennsylvania State University CiteSeerX Archives |
| المصدر: | http://arxiv.org/pdf/0810.2961v2.pdf. |
| سنة النشر: | 2008 |
| المجموعة: | CiteSeerX |
| مصطلحات موضوعية: | Key words. Gamma rays, bursts – Methods, numerical – Magnetohydrodynamics (MHD) – Shock waves |
| الوصف: | Context. The role of magnetic fields in gamma-ray burst (GRB) flows remains debated. If strong enough, they can leave their signature on the initial phases of the afterglow by substantially changing the backreaction of the flow as a consequence of its interaction with the external medium. Aims. We aim to quantitatively understand the dynamical effect and observational signatures of magnetization of the GRB ejecta on the onset of the afterglow. Methods. 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 complete evolution of an ultrarelativistic shell all the way to a the self-similar asymptotic phase. Results. Our simulations show that the complete evolution can be characterized in terms of two parameters, namely, theξparameter introduced by Sari & Piran (1995) and the magnetizationσ0. We exploit this property by producing numerical models where the shell Lorentz factor is γ0 ∼ tens and rescaling the results to arbitrarily largeγ0. We find that the reverse shock is typically very weak or absent for ejecta characterized byσ0> ∼ 1. The onset of the forward shock emission is strongly affected by the magnetization. On the other hand, the magnetic energy of the shell is transferred to the external medium on a short timescale (∼several times the duration of the burst). The later forward shock emission |
| نوع الوثيقة: | text |
| وصف الملف: | application/pdf |
| اللغة: | English |
| Relation: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.244.781; http://arxiv.org/pdf/0810.2961v2.pdf |
| الاتاحة: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.244.781 http://arxiv.org/pdf/0810.2961v2.pdf |
| Rights: | Metadata may be used without restrictions as long as the oai identifier remains attached to it. |
| رقم الانضمام: | edsbas.286835B |
| قاعدة البيانات: | BASE |
| الوصف غير متاح. |