1,744 research outputs found
Dynamical Evolution of an Ultra-relativistic Fireball Colliding with a Freely Expanding Gas
We investigate the hydrodynamical evolution of an ultra-relativistic fireball
colliding with a freely expanding gas. The hydrodynamical interaction of the
fireball and the gas results in the formation of a geometrically thin shell. We
study the dynamical evolution of the shell by an analytical way and perform a
numerical simulation equipped with an adaptive mesh refinement to investigate
the internal structure of the shell. The shocked gas can give rise to bright
emission in the X-ray and gamma-ray energy range. We propose that the breakout
emission from the forward shock and the photospheric emission from the
reverse-shocked fireball contribute to early gamma-ray emission from gamma-ray
bursts.Comment: 15 pages, 9 figures, accepted for publication in Ap
A novel method to construct stationary solutions of the Vlasov-Maxwell system : the relativistic case
A method to derive stationary solutions of the relativistic Vlasov-Maxwell
system is explored. In the non-relativistic case, a method using the Hermite
polynomial series to describe the deviation from the Maxwell-Boltzmann
distribution is found to be successful in deriving a few stationary solutions
including two dimensional one. Instead of the Hermite polynomial series, two
special orthogonal polynomial series, which are appropriate to expand the
deviation from the Maxwell-J\"uttner distribution, are introduced in this
paper. By applying this method, a new two-dimensional equilibrium is derived,
which may provide an initial setup for investigations of three-dimensional
relativistic collisionless reconnection of magnetic fields.Comment: 15pages, 2 figures, to appear in Phys. Plasma
Early evolution of spherical ejecta expanding into the circumstellar matter at ultra-relativistic speeds
We present a new self-similar solution describing early evolution of an
ultra-relativistic flow resulting from a collision of homologously expanding
spherical ejecta with the circumstellar matter, in which a shock wave
propagates in the circumstellar matter while a weak discontinuity propagates in
the ejecta at the sound speedComment: 5 pages, 2 figures, accepted for publication in PAS
- …