2003A&A...401..593W


C.D.S. - SIMBAD4 rel 1.7 - 2019.11.19CET20:28:34

2003A&A...401..593W - Astronomy and Astrophysics, volume 401, 593-597 (2003/4-2)

Possible geometries of afterglow generation in the gamma-ray burst GRB 990705.

WANG X.Y., DAI Z.G. and LU T.

Abstract (from CDS):

The absorption feature detected in the prompt X-ray emission of GRB 990705 has important consequences for its circum-burst environment and therefore on its afterglow. Here we investigate whether the circum-burst environment constrained by the absorption feature could be consistent with the observed H-band afterglow, which exhibits an earlier power law decay (F∝t–1.68) but a much faster decay (α>2.6; F∝t–α) about one day after the burst. Two possible geometries of the afterglow-emitting regions are suggested: 1) afterglow emission produced by the impact of the fireball on the surrounding torus, which serves as the absorbing material of the X-ray feature, as would be expected in the models involving that a supernova explosion precedes the gamma-ray burst by some time; 2) afterglow emission produced in the dense circum-burst medium inside the torus. In case 1), the faster decay at the later time is attributed to the disappearance of the shock due to the counter-pressure in the hot torus illuminated by the burst and afterglow photons. For case 2), the circum-burst medium density is found to be very high (n>104-105cm–3) if the emitting plasma is a jet or even higher if it is spherical. Future better observations of afterglows of GRBs that have absorption features might make it possible to make a more definite choice between these two scenarios.

Abstract Copyright:

Journal keyword(s): gamma rays: bursts - line: formation - radiation mechanism: nonthermal

Simbad objects: 6

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Number of rows : 6

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 GRB 991216 gB 05 09 31.2983 +11 17 07.262           ~ 402 1
2 GRB 990705 gB 05 09 54.5 -72 07 53           ~ 211 1
3 GRB 970508 gB 06 53 49.2 +79 16 19           ~ 835 1
4 GRB 011211 gB 11 15 16 -21 56.0           ~ 282 1
5 GRB 970828 gB 18 08 31.6 +59 18 51           ~ 333 1
6 GRB 000214 gB 18 54 27.0 -66 27 30           ~ 89 0

    Equat.    Gal    SGal    Ecl

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2019.11.19-20:28:34

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