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Title: A very low luminosity X-ray flash: XMM-NEWTON observations of GRB 031203
Authors: Watson, D.
Hjorth, J.
Levan, A.
Jakobsson, P.
O'Brien, Paul T.
Osborne, Julian P.
Pedersen, K.
Reeves, J.N.
Tedds, J.A.
Vaughan, S.A.
Ward, M.J.
Willingale, Richard
First Published: 20-Apr-2004
Publisher: IOP Publishing Ltd
Citation: Astrophysical Journal, 2004, 605 (2), pp. L101-L104
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 (4.2 ± 0.1) × 10[superscript -13] and (1.8 ± 0.1) × 10[superscript -13] ergs cm[superscript -2] s[superscript -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 (≲-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 0."5 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 × 10[superscript 49] ergs) and X-ray luminosity in the afterglow (9 × 10[superscript 42] ergs s[superscript -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
ISSN: 0004-637X
eISSN: 1538-4357
Version: Publisher Version
Status: Peer-reviewed
Type: Journal Article
Rights: Copyright © 2004, The American Astronomical Society. Deposited with reference to the publisher’s archiving policy available on the SHERPA/RoMEO website.
Appears in Collections:Published Articles, Dept. of Physics and Astronomy

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