The X-Ray Afterglow of the Gamma-Ray Burst of 1997 May 8:Spectral Variability and Possible Evidence of an Iron Line

Piro, L.; Costa, E.; Feroci, M.; Frontera, F.; Amati, L.; Fiume, D. Dal; Antonelli, L. A.; Heise, J.; Zand, J. in ’t; Owens, A.; Parmar, A. N.; Cusumano, G.; Vietri, M.; Perola, G. C.

doi:10.1086/311946

Cited by 157 publications

(122 citation statements)

References 21 publications

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“…An iron line was reported in BeppoSAX NFI X-ray spectra of GRB 970508 (Piro et al 1999). Since this line is not highly blueshifted, it must come from material that does not participate in the relativistic outflow.…”

Section: Finite Optical Depths Prompt Emission and Linesmentioning

confidence: 96%

Gamma-Ray Burst Afterglows

Paradijs

Kouveliotou

Wijers

2000

Annu. Rev. Astron. Astrophys.

322

248

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The discovery of counterparts in X-ray and optical to radio wavelengths has revolutionized the study of γ -ray bursts, until recently the most enigmatic of astrophysical phenomena. We now know that γ -ray bursts are the biggest explosions in nature, caused by the ejection of ultrarelativistic matter from a powerful energy source and its subsequent collision with its environment. We have just begun to uncover a connection between supernovae and γ -ray bursts, and are finally constraining the properties of the ultimate source of γ -ray burst energy. We review here the observations that have led to this breakthrough in the field; we describe the basic theory of the fireball model and discuss the theoretical understanding that has been gained from interpreting the new wealth of data on γ -ray bursts.

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Section: Finite Optical Depths Prompt Emission and Linesmentioning

confidence: 96%

Gamma-Ray Burst Afterglows

Paradijs

Kouveliotou

Wijers

2000

Annu. Rev. Astron. Astrophys.

322

248

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“…Indeed, there have been numerous claims in the literature for the detection of X-ray emission-lines in the X-ray spectra of GRB afterglows across a number of X-ray platforms including BeppoSax, Chandra and XMM (e.g. Piro et al 1999;Piro et al 2000;Yoshida et al 2001;Reeves et al 2002;Butler et al 2003;Watson et al 2003), though in the majority of cases the detection significance is modest (a few σ) at best. Line species identified include FeKα, with an energy consistent with the redshift of the host galaxies, and/or lines associated with blue-shifted lighter elements of S, Si, Ar, Mg and Ca.…”

Section: Introductionmentioning

confidence: 99%

Swift multi-wavelength observations of the bright flaring burst GRB 051117A

Goad

Page

Godet

et al. 2007

A&A

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We report on the temporal and spectral characteristics of the early X-ray emission from the Gamma Ray Burst 051117A as observed by Swift. The superb quality of the early X-ray light-curve and spectra of this source, one of the brightest seen by the X-ray Telescope at such early times, allows an unprecedented look at the spectral and temporal evolution of the prompt and early afterglow emission for this GRB and allows us to place stringent limits on the detection of lines. GRB 051117A displays a highly complex light-curve, with an apparent initial slow decline of slope α = 0.77 ± 0.07 ( f (t) ∝ t −α ) dominated by numerous superposed flares of varying amplitude and duration. Between orbits 2 and 3, the X-ray light-curve drops abruptly, highlighting the dominance of flaring activity at early times, and indicating that the central engine for this burst remains active for several kiloseconds after the initial explosion. The late time slope (t > 10 4 s) also decays relatively slowly with a powerlaw index of α = 0.66, breaking to a steeper slope of 1.1, 170 ks after the BAT trigger. The X-ray light-curve at early times is characteristic of a noise process, consisting of random shots superposed on an underlying powerlaw decay, with individual shots well-modelled by a fast-rise and exponential decay spanning a broad range in rise-times and decay rates. A temporal spectral analysis of the early light-curve shows that the photon index and source intensity are highly correlated with the spectrum being significantly harder when brighter, consistent with the movement of the peak of the Band function to lower energies following individual flares. The high quality spectrum obtained from the first orbit of WT mode data, enables us to place a 3σ upper limit on the strength of any emission line features of EW < 15 eV, assuming a narrow emission-line of 100 eV at the peak of the effective area.

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“…Its overall shape is similar to the one typically observed by the XRT Nousek et al 2006), even though the initial slope is less steep than average. The most striking characteristic of this burst is the strong flare in its X-ray light curve, a feature which had never been detected by Swift before and had been previously observed in very few GRBs (GRB 970508, Piro et al 1999; GRB 011121 and GRB 011211, Piro et al 2005). The fluence of the flare is ∼ 1.4 × 10 −8 erg cm −2 in the 0.2-10 keV band, which amounts to ∼ 14 % of the observed (15-350 keV band) prompt fluence.…”

Section: X-ray Flares: Evidence For Prolonged Engine Activitymentioning

confidence: 69%

X-ray flare in XRF 050406: evidence for prolonged engine activity

Romano

Moretti

Banat

et al. 2006

AIP Conference Proceedings

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Abstract. We present observations of XRF 050406, the first burst detected by Swift showing a flare in its X-ray light curve. During this flare, which peaks at t peak ∼ 210 s after the BAT trigger, a flux variation of δF/F ∼ 6 in a very short time δt/t peak ≪ 1 was observed. Its measured fluence in the 0.2-10 keV band was ∼ 1.4 × 10 −8 erg cm −2 , which corresponds to 1-15% of the prompt fluence. We present indications of spectral variations during the flare. We argue that the producing mechanism is late internal shocks, which implies that the central engine is still active at 210 s, though with a reduced power with respect to the prompt emission. The X-ray light curve flattens to a very shallow slope with decay index of ∼ 0.5 after ∼ 4400 s, which also supports continued central engine activity at late times. This burst is classified as an X-ray flash, with a relatively low fluence (∼ 10 −7 erg cm −2 in the 15-350 keV band, E iso ∼ 10 51 erg), a soft spectrum (photon index 2.65), no significant flux above ∼ 50 keV and a peak energy E p < 15 keV. XRF 050406 is one of the first examples of a well-studied X-ray light curve of an XRF. We show that the main afterglow characteristics are qualitatively similar to those of normal GRBs. In particular, X-ray flares superimposed on a power-law light curve have now been seen in both XRFs and GRBs. This indicates that a similar mechanism may be at work for both kinds of events.

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The X-Ray Afterglow of the Gamma-Ray Burst of 1997 May 8:Spectral Variability and Possible Evidence of an Iron Line

Cited by 157 publications

References 21 publications

Gamma-Ray Burst Afterglows

Gamma-Ray Burst Afterglows

Swift multi-wavelength observations of the bright flaring burst GRB 051117A

X-ray flare in XRF 050406: evidence for prolonged engine activity

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