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Title: A Very Low Luminosity X-Ray Flash: XMM-Newton Observations of GRB 031203
Authors: Watson, D.
Hjorth, J.
Levan, Andrew J.
Jakobsson, P.
O'Brien, Paul T.
Osborne, Julian P.
Pedersen, K.
Reeves, J. N.
Tedds, J. A.
Vaughan, Simon A.
Ward, M. J.
Willingale, Richard
First Published: 25-Mar-2004
Publisher: American Astronomical Society, IOP Publishing
Citation: Astrophysical Journal Letters, 2004, 605 (2), pp.101-104
Abstract: GRB 031203 was observed by XMM-Newton twice, first with an observation beginning 6 hr after the burst and again after 3 days. The afterglow had average 0.2-10.0 keV fluxes for the first and second observations of img1.gif × 10-13 and img2.gif × 10-13 ergs cm-2 s-1, respectively, decaying very slowly according to a power law with an index of -0.55 ± 0.05. The prompt soft X-ray flux, inferred from a detection of the dust echo of the prompt emission, strongly implies that this burst is very soft and should be classified as an X-ray flash (XRF) and further, implies a steep temporal slope (lesssim-1.7) between the prompt and afterglow phases or in the early afterglow, very different from the later afterglow decay slope. A power law (Γ = 1.90 ± 0.05) with absorption at a level consistent with the Galactic foreground absorption fits the afterglow spectrum well. A bright low-redshift (z = 0.105) galaxy lies within 0farcs5 of the X-ray position and is likely to be the gamma-ray burst (GRB) host. At this redshift, GRB 031203 is the closest GRB or XRF known after GRB 980425. It has a very low equivalent isotropic gamma-ray energy in the burst (~3 × 1049 ergs) and X-ray luminosity in the afterglow (9 × 1042 ergs s-1 at 10 hr), 3-4 orders of magnitude less than typical bursts, though higher than either the faint XRF 020903 or GRB 980425. The rapid initial decline and subsequent very slow fading of the X-ray afterglow is also similar to that observed in GRB 980425, indicating that GRB 031203 may be representative of low-luminosity bursts.
DOI Link: 10.1086/420844
Type: Article
Rights: Archived with reference to SHERPA/RoMEO and publisher website. Copyright 2004. The American Astronomical Society. All rights reserved.
Appears in Collections:Published Articles, Dept. of Physics and Astronomy

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