Open AccessA possible explanation for the radio afterglow of GRB 980519: the dense medium effect
Author(s) -
Wang X. Y.,
Dai Z. G.,
Lu T.
Publication year - 2000
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2000.03660.x
Subject(s) - afterglow , physics , gamma ray burst , astrophysics , light curve , outflow , interstellar medium , astronomy , shock wave , galaxy , sublimation (psychology) , mechanics , meteorology , psychology , psychotherapist
GRB 980519 is characterized by its rapidly declining optical and X‐ray afterglows. Explanations of this behaviour include models invoking a dense medium environment, which makes the shock wave evolve quickly into the subrelativistic phase, a jet‐like outflow, and a wind‐shaped circumburst medium environment. Recently, Frail et al. found that the latter two cases are consistent with the radio afterglow of this burst. Here, by considering the transrelativistic shock hydrodynamics, we show that the dense medium model can also account for the radio light curve quite well. The potential virtue of the dense medium model for GRB 980519 is that it implies a smaller angular size of the afterglow, which is essential for interpreting the strong modulation of the radio light curve. Optical extinction arising from the dense medium is not important if the prompt optical–UV flash accompanying the γ ‐ray emission can destroy dust by sublimation out to an appreciable distance. Comparisons with some other radio afterglows are also discussed.