Optical observations of the bright long duration peculiar GRB 021004 afterglow

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dc.creatorPandey, S. B.
dc.creatorSahu, D. K.
dc.creatorResmi, L.
dc.creatorSagar, R.
dc.creatorAnupama, G. C.
dc.creatorBhattacharya, D.
dc.creatorMohan, V.
dc.creatorPrabhu, T. P.
dc.creatorBhatt, B. C.
dc.creatorPandey, J. C.
dc.creatorParihar, Padmaker
dc.creatorCastro-Tirado, A. J.
dc.date2002-11-06
dc.date2003-10-17
dc.date.accessioned2026-07-07T02:06:03Z
dc.date.available2026-07-07T02:06:03Z
dc.descriptionThe CCD magnitudes in Johnson $B,V$ and Cousins $R$ and $I$ photometric passbands are determined for the bright long duration GRB 021004 afterglow from 2002 October 4 to 16 starting $\sim$ 3 hours after the $γ-$ray burst. Light curves of the afterglow emission in $B$,$V$,$R$ and $I$ passbands are obtained by combining these measurements with other published data. The earliest optical emission appears to originate in a revese shock. Flux decay of the afterglow shows a very uncommon variation relative to other well-observed GRBs. Rapid light variations, especially during early times ($Δt < 2$ days) is superposed on an underlying broken power law decay typical of a jetted afterglow. The flux decay constants at early and late times derived from least square fits to the light curve are $0.99\pm0.05$ and $2.0\pm0.2$ respectively, with a jet break at around 7 day. Comparison with a standard fireball model indicates a total extinction of $E(B-V)=0.20$ mag in the direction of the burst. Our low-resolution spectra corrected for this extinction provide a spectral slope $β= 0.6\pm0.02$. This value and the flux decay constants agree well with the electron energy index $p\sim 2.27$ used in the model. The derived jet opening angle of about $7^{\circ}$ implies a total emitted gamma-ray energy $E_γ = 3.5\times10^{50}$ erg at a cosmological distance of about 20 Gpc. Multiwavelength observations indicate association of this GRB with a star forming region, supporting the case for collapsar origin of long duration GRBs.
dc.description19 pages, 3 figures, BASI, 31, 19
dc.identifierhttps://arxiv.org/abs/astro-ph/0211108
dc.identifierhttp://arxiv.org/abs/astro-ph/0211108
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/5294
dc.subjectAstrophysics
dc.titleOptical observations of the bright long duration peculiar GRB 021004 afterglow
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