Document Type
Article
Publication Date
7-20-2021
Publication Title
Monthly Notices of the Royal Astronomical Society
Publisher
Oxford University Press
Volume
507
Issue
2
First page number:
1788
Last page number:
1794
Abstract
The evolution of a relativistic blastwave is usually delineated under the assumption of pressure balance between forward- and reverse-shocked regions. However, such a treatment usually violates the energy conservation law, and is inconsistent with existing magnetohydrodynamic numerical simulation results. A mechanical model of non-magnetized blastwaves was proposed in previous work to solve the problem. In this paper, we generalize the mechanical model to the case of a blastwave driven by an ejecta with an arbitrary magnetization parameter $\sigma_{\rm ej}$. We test our modified mechanical model by considering a long-lasting magnetized ejecta and found that it is much better than the pressure-balance treatment in terms of energy conservation. For a constant central engine wind luminosity $L_{ \ rm ej} = 10^{47} { \ rm erg ~ s^{-1}}$ and $ \ sigma_{ \ rm ej} < 10$, the deviation from energy conservation is negligibly small at small radii but only reaches less than $25{{\ \rm per\ cent}}$ even at 1019 cm from the central engine. For a finite lifetime of the central engine, the reverse shock crosses the magnetized ejecta earlier for the ejecta with a higher $\sigma_{\rm ej}$, which is consistent with previous analytical and numerical results. In general, the mechanical model is more precise than the traditional analytical models with results closer to those of numerical simulations.
Keywords
Gamma-ray bursts; MHD; Shock waves
Disciplines
Astrophysics and Astronomy | Physical Processes
File Format
File Size
427 KB
Language
English
Rights
IN COPYRIGHT. For more information about this rights statement, please visit http://rightsstatements.org/vocab/InC/1.0/
Repository Citation
Ai, S.,
Zhang, B.
(2021).
A Mechanical Model for Magnetized Relativistic Blastwaves.
Monthly Notices of the Royal Astronomical Society, 507(2),
1788-1794.
Oxford University Press.
http://dx.doi.org/10.1093/mnras/stab2000
Comments
This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society ©: 2021 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved.