GRB 050822: Detailed analysis of an XRF observed by Swift

O. Godet, K. L. Page, J. Osborne, B. Zhang, D. N. Burrows, P. T. O'Brien, J. E. Hill, J. Racusin, A. P. Beardmore, M. R. Goad, A. Falcone, D. C. Morris, H. Ziaeepour

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

We report on the temporal and spectral characteristics of the early X-ray emission from the GRB 050822 as observed by Swift. This burst is likely to be an XRF showing major X-ray flares in its XRT light-curve. The quality of the data allows a detailed spectral analysis of the early afterglow in the X-ray band. During the X-ray flares, a positive correlation between the count rate and the spectral hardness (i.e. the higher the count rate, the harder the spectrum) is clearly seen for the X-ray flares. This behaviour, similar to that seen for Gamma-ray pulses, indicates that the energy peak of the spectrum is in the XRT energy band and it moves towards lower energies with time. We show evidence for the possible detection of the emergence of the forward-shock emission, produced at a radius larger than 4 × 1016 cm in the case of a CBM afterglow model (a formation region clearly different from that producing the prompt emission). Finally, we show that the null detection of a jet break up to T0 + 4 x 106 s in the X-ray light curve of this XRF can be understood: i) if the jet seen on-axis is uniform with a large opening angle (θ > 20°); or ii) if the jet is a structured Gaussian-like jet with the line-of-sight outside the bright Gaussian core.

Original languageEnglish (US)
Pages (from-to)385-394
Number of pages10
JournalAstronomy and Astrophysics
Volume471
Issue number2
DOIs
StatePublished - Aug 1 2007

Fingerprint

X-ray fluorescence
flares
x rays
afterglows
light curve
energy
spectral analysis
line of sight
hardness
energy bands
spectrum analysis
analysis
bursts
shock
gamma rays
radii
pulses

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Godet, O., Page, K. L., Osborne, J., Zhang, B., Burrows, D. N., O'Brien, P. T., ... Ziaeepour, H. (2007). GRB 050822: Detailed analysis of an XRF observed by Swift. Astronomy and Astrophysics, 471(2), 385-394. https://doi.org/10.1051/0004-6361:20077266
Godet, O. ; Page, K. L. ; Osborne, J. ; Zhang, B. ; Burrows, D. N. ; O'Brien, P. T. ; Hill, J. E. ; Racusin, J. ; Beardmore, A. P. ; Goad, M. R. ; Falcone, A. ; Morris, D. C. ; Ziaeepour, H. / GRB 050822 : Detailed analysis of an XRF observed by Swift. In: Astronomy and Astrophysics. 2007 ; Vol. 471, No. 2. pp. 385-394.
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Godet, O, Page, KL, Osborne, J, Zhang, B, Burrows, DN, O'Brien, PT, Hill, JE, Racusin, J, Beardmore, AP, Goad, MR, Falcone, A, Morris, DC & Ziaeepour, H 2007, 'GRB 050822: Detailed analysis of an XRF observed by Swift', Astronomy and Astrophysics, vol. 471, no. 2, pp. 385-394. https://doi.org/10.1051/0004-6361:20077266

GRB 050822 : Detailed analysis of an XRF observed by Swift. / Godet, O.; Page, K. L.; Osborne, J.; Zhang, B.; Burrows, D. N.; O'Brien, P. T.; Hill, J. E.; Racusin, J.; Beardmore, A. P.; Goad, M. R.; Falcone, A.; Morris, D. C.; Ziaeepour, H.

In: Astronomy and Astrophysics, Vol. 471, No. 2, 01.08.2007, p. 385-394.

Research output: Contribution to journalArticle

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T2 - Detailed analysis of an XRF observed by Swift

AU - Godet, O.

AU - Page, K. L.

AU - Osborne, J.

AU - Zhang, B.

AU - Burrows, D. N.

AU - O'Brien, P. T.

AU - Hill, J. E.

AU - Racusin, J.

AU - Beardmore, A. P.

AU - Goad, M. R.

AU - Falcone, A.

AU - Morris, D. C.

AU - Ziaeepour, H.

PY - 2007/8/1

Y1 - 2007/8/1

N2 - We report on the temporal and spectral characteristics of the early X-ray emission from the GRB 050822 as observed by Swift. This burst is likely to be an XRF showing major X-ray flares in its XRT light-curve. The quality of the data allows a detailed spectral analysis of the early afterglow in the X-ray band. During the X-ray flares, a positive correlation between the count rate and the spectral hardness (i.e. the higher the count rate, the harder the spectrum) is clearly seen for the X-ray flares. This behaviour, similar to that seen for Gamma-ray pulses, indicates that the energy peak of the spectrum is in the XRT energy band and it moves towards lower energies with time. We show evidence for the possible detection of the emergence of the forward-shock emission, produced at a radius larger than 4 × 1016 cm in the case of a CBM afterglow model (a formation region clearly different from that producing the prompt emission). Finally, we show that the null detection of a jet break up to T0 + 4 x 106 s in the X-ray light curve of this XRF can be understood: i) if the jet seen on-axis is uniform with a large opening angle (θ > 20°); or ii) if the jet is a structured Gaussian-like jet with the line-of-sight outside the bright Gaussian core.

AB - We report on the temporal and spectral characteristics of the early X-ray emission from the GRB 050822 as observed by Swift. This burst is likely to be an XRF showing major X-ray flares in its XRT light-curve. The quality of the data allows a detailed spectral analysis of the early afterglow in the X-ray band. During the X-ray flares, a positive correlation between the count rate and the spectral hardness (i.e. the higher the count rate, the harder the spectrum) is clearly seen for the X-ray flares. This behaviour, similar to that seen for Gamma-ray pulses, indicates that the energy peak of the spectrum is in the XRT energy band and it moves towards lower energies with time. We show evidence for the possible detection of the emergence of the forward-shock emission, produced at a radius larger than 4 × 1016 cm in the case of a CBM afterglow model (a formation region clearly different from that producing the prompt emission). Finally, we show that the null detection of a jet break up to T0 + 4 x 106 s in the X-ray light curve of this XRF can be understood: i) if the jet seen on-axis is uniform with a large opening angle (θ > 20°); or ii) if the jet is a structured Gaussian-like jet with the line-of-sight outside the bright Gaussian core.

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