2002A&A...381..731W


C.D.S. - SIMBAD4 rel 1.7 - 2020.12.03CET19:41:02

2002A&A...381..731W - Astronomy and Astrophysics, volume 381, 731-735 (2002/1-2)

Are some breaks in GRB afterglows caused by their spectra?

WEI D.M. and LU T.

Abstract (from CDS):

Sharp breaks have been observed in the afterglow light curves of several GRBs; this is generally explained by the jet model. However, there are still some uncertainties concerning this interpretation due to the unclear hydrodynamics of jet sideways expansion. Here we propose an alternative explanation to these observed breaks. If we assume that the multiwavelength spectra of GRB afterglows are not made of exact power law segments but their slope changes smoothly, i.e. dβ/d(logν)<0, where β is the spectral index, we find that this fact can very nicely explain the afterglow light curves showing breaks. Therefore we suggest that some breaks in the afterglow light curves may be caused by their curved spectra. The main feature of this interpretation is that the break time is dependent on the observed frequency, while the jet model produces achromatic breaks in the light curves. In addition, it is very important to know the position of the characteristic frequency νc in the multiwavelength spectrum at the time of the break, since it is a further discriminant between our model and the jet model. We find that although the optical light curves of seven GRB afterglows can be well fitted by the model we propose, in fact only one of them (i.e. GRB000926) can be explained in this framework, since for the others the characteristic frequency νc is either above the optical after the break or below the optical before the break.

Abstract Copyright:

Journal keyword(s): gamma rays: bursts

Simbad objects: 8

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Number of rows : 8

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 GRB 991216 gB 05 09 31.2983 +11 17 07.262           ~ 409 1
2 GRB 990705 gB 05 09 54.5 -72 07 53           ~ 215 1
3 GRB 990510 gB 13 38 07.64 -80 29 48.8           ~ 467 1
4 GRB 010222 gB 14 52 12.55 +43 01 06.3           ~ 336 2
5 GRB 990123 gB 15 25 29 +44 45.0     8.95     ~ 965 1
6 GRB 000301C gB 16 20 18.5 +29 26 35           ~ 341 2
7 GRB 991208 gB 16 33 53.51 +46 27 21.5           ~ 244 1
8 GRB 000926 gB 17 04 15 +51 46.0           ~ 342 2

    Equat.    Gal    SGal    Ecl

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2020.12.03-19:41:03

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