skip to main content

SciTech ConnectSciTech Connect

Title: HOT ELECTROMAGNETIC OUTFLOWS. II. JET BREAKOUT

We consider the interaction between radiation, matter, and a magnetic field in a compact, relativistic jet. The entrained matter accelerates outward as the jet breaks out of a star or other confining medium. In some circumstances, such as gamma-ray bursts (GRBs), the magnetization of the jet is greatly reduced by an advected radiation field while the jet is optically thick to scattering. Where magnetic flux surfaces diverge rapidly, a strong outward Lorentz force develops and radiation and matter begin to decouple. The increase in magnetization is coupled to a rapid growth in Lorentz factor. We take two approaches to this problem. The first examines the flow outside the fast magnetosonic critical surface, and calculates the flow speed and the angular distribution of the radiation field over a range of scattering depths. The second considers the flow structure on both sides of the critical surface in the optically thin regime, using a relaxation method. In both approaches, we find how the terminal Lorentz factor and radial profile of the outflow depend on the radiation intensity and optical depth at breakout. The effect of bulk Compton scattering on the radiation spectrum is calculated by a Monte Carlo method, while neglecting the effectsmore » of internal dissipation. The peak of the scattered spectrum sits near the seed peak if radiation pressure dominates the acceleration, but is pushed to a higher frequency if the Lorentz force dominates. The unscattered seed radiation can form a distinct, low-frequency component of the spectrum, especially if the magnetic Poynting flux dominates.« less
Authors:
 [1] ;  [2]
  1. Department of Physics, University of Toronto, 60 St. George Street, Toronto, ON M5S 1A7 (Canada)
  2. Canadian Institute for Theoretical Astrophysics, 60 St. George Street, Toronto, ON M5S 3H8 (Canada)
Publication Date:
OSTI Identifier:
22131019
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 773; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ANGULAR DISTRIBUTION; COMPTON EFFECT; COSMIC GAMMA BURSTS; LORENTZ FORCE; MAGNETIC FIELDS; MAGNETIC FLUX; MAGNETIZATION; MONTE CARLO METHOD; RADIANT HEAT TRANSFER; RADIATION PRESSURE; RELATIVISTIC RANGE; RELAXATION; SPECTRA; STARS