The evolution of GRB remnants

Abstract

The detection of the delayed emission in X-ray, optical and radio band, i.e. the afterglow of $\gamma$-ray bursts (GRBs), suggestes that the sources of GRBs are likely to be at cosmological distances. Here we explore the interaction of a relativistic shell with a uniform interstellar medium (ISM) and obtain the exact solution of the evolution of $\gamma$-ray burst remnants, including the radiative losses. We show that in general the evolution of bulk Lorentz factor $\gamma$ satisfies $\gamma \propto t^{-{\alpha }_t}$ when $\gamma \gg 1$, here ${\alpha }_t$ is mainly in the range $9/22\sim 3/8$, the latter corresponds to adiabatic expansion. So it is clear that adiabatic expansion is a good approximation even when radiative loss is considered. However, in fact, ${\alpha }_t$ is slightly larger than 3/8, which may have some effects on a detailed data analysis. Synchrotron-self-absorption is also calculated and it is demonstrated that the radio emission may become optically thin during the afterglow. Our solution can also apply to the nonrelativistic case ($\gamma \sim 1$), at that time the observed flux decrease more rapidly than that in the relativistic case.

15pages,1 figure, accepted by ApJ,aasms4 style

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Cited by in corpus (10)

• Dynamical Evolution, Light-Curves and Spectra of Spherical and Collimated Gamma-Ray Burst Remnants
• Diverse Temporal Properties of GRB Afterglow
• Gamma-Ray Bursts: Afterglows and Central Engines
• Can the jet steepen the light curves of GRB afterglow?
• Can all breaks in GRB afterglows be explained by jet effects?
• Are some breaks in GRB afterglows caused by their spectra?
• Dynamical Evolution of Gamma-Ray Burst Remnants with Evolving Radiative Efficiency
• The evolution of beamed GRB afterglow: non-relativistic case
• Statistical Shapes of the Highest Pulses in Gamma--Ray Bursts
• What do $\gamma$-ray bursts look like?