Swift observations of GRB 050904: the most distant cosmic
explosion ever observed

Cusumano, G.; Mangano, V.; Chincarini, G.; Panaitescu, A.; Burrows, D. N.; Parola, V. La; Sakamoto, T.; Campana, S.; Mineo, T.; Tagliaferri, G.; Angelini, L.; Barthelmy, S. D.; Beardmore, A. P.; Boyd, Patricia T.; Cominsky, L.; Grönwall, C.; Fenimore, E. E.; Gehrels, N.; Giommi, P.; Goad, M. R.; Hurley, K.; Immler, S.; Kennea, J. A.; Mason, K. O.; Marshal, F.; Mészáros, P.; Nousek, J. A.; Osborne, J. P.; Palmer, D. M.; Roming, P. W. A.; Wells, A.; White, N. E.; Zhang, Bing

doi:10.1051/0004-6361:20065173

Cited by 26 publications

(14 citation statements)

References 66 publications

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“…Although such late brightenings or flares are not unprecedented, only a few bursts have exhibited them so far: e.g. GRB 970508 (Piro et al 1998;Galama et al 1998), the short GRB 050724 (Campana et al 2006;Malesani et al 2007), the z = 6.3 GRB 050904 (Cusumano et al 2007;Watson et al 2006). We also note the presence of the shallow decay phase preceding the X-ray brightening (or corresponding to its gradual onset).…”

Section: Discussionmentioning

confidence: 62%

GRB 070311: a direct link between the prompt emission and the afterglow

Guidorzi

Vergani

Sazonov

et al. 2007

A&A

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Context. The prompt emission of gamma-ray bursts is mostly thought to be produced in internal shocks of relativistic shells emitted by the progenitor at different times, whereas the late multi-band afterglow is interpreted as the synchrotron emission of electrons swept up by the fireball expanding through the surrounding interstellar medium. The short timescale variability observed in flares superimposed on the X-ray/optical afterglow of several bursts, recently made possible by Swift, has been interpreted as evidence for prolonged activity of the inner engine through internal shocks. Yet, it is not clear whether this applies to all the observed bursts and, in particular, whether the bursts exhibiting single γ-ray pulses with no short timescale variability at late times could also be entirely interpreted as external shocks. Aims. We present prompt γ-ray, early NIR/optical, late optical and X-ray observations of the peculiar GRB 070311 discovered by INTEGRAL, in order to gain clues on the mechanisms responsible for the prompt γ-ray pulse as well as for the early and late multiband afterglow of GRB 070311. Methods. We fitted with empirical functions the gamma-ray and optical light curves and scaled the result to the late time X-rays. Results. The H-band light curve taken by REM shows two pulses peaking 80 and 140 s after the peak of the γ-ray burst and possibly accompanied by a faint γ-ray tail. Remarkably, the late optical and X-ray afterglow underwent a major rebrightening between 3 × 10 4 and 2 × 10 5 s after the burst with an X-ray fluence comparable with that of the prompt emission extrapolated in the same band. Notably, the time profile of the late rebrightening can be described as the combination of a time-rescaled version of the prompt γ-ray pulse and an underlying power law. Conclusions. This result supports a common origin for both prompt and late X-ray/optical afterglow rebrightening of GRB 070311 within the external shock scenario. The main fireball would be responsible for the prompt emission, while a second shell would produce the rebrightening when impacting the leading blastwave in a refreshed shock.

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Section: Discussionmentioning

confidence: 62%

GRB 070311: a direct link between the prompt emission and the afterglow

Guidorzi

Vergani

Sazonov

et al. 2007

A&A

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“…Specifically, for GRB 080319B and GRB 050904, both time-resolved and time-integrated BAT spectra, including the proper-GRB (P-GRB, see below Section 3.1) spectrum of GRB 080319B, are best fit by a simple power law (see Sections 4 and 5; see also Racusin et al 2008;Stamatikos et al 2009;Cusumano et al 2007); alternative models, such as a Band function or a BB+PL, cannot be constrained by the BAT data. No concluding statements on the presence of a blackbody component in the P-GRB of GRB 080319B can be made due to the limited bandpass of the instruments (see Section 4).…”

Section: Phenomenological Approaches To Grb Prompt Emissionmentioning

confidence: 99%

Analysis of GRB 080319b and GRB 050904 Within the Fireshell Model: Evidence for a Broader Spectral Energy Distribution

Patricelli¹,

Bernardini²,

Bianco³

et al. 2012

ApJ

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The observation of GRB 080319B, with an isotropic energy E iso = 1.32 × 10 54 erg, and GRB 050904, with E iso = 1.04 × 10 54 erg, offers the possibility of studying the spectral properties of the prompt radiation of two of the most energetic gamma-ray bursts (GRBs). This allows us to probe the validity of the fireshell model for GRBs beyond 10 54 erg, well outside the energy range where it has been successfully tested up to now (10 49 -10 53 erg). We find that in the low-energy region, the prompt emission spectra observed by Swift Burst Alert Telescope (BAT) reveals more power than theoretically predicted. The opportunities offered by these observations to improve the fireshell model are outlined in this paper. One of the distinguishing features of the fireshell model is that it relates the observed GRB spectra to the spectrum in the comoving frame of the fireshell. Originally, a fully radiative condition and a comoving thermal spectrum were adopted. An additional power law in the comoving thermal spectrum is required due to the discrepancy of the theoretical and observed light curves and spectra in the fireshell model for GRBs 080319B and 050904. A new phenomenological parameter α is correspondingly introduced in the model. We perform numerical simulations of the prompt emission in the Swift BAT bandpass by assuming different values of α within the fireshell model. We compare them with the GRB 080319B and GRB 050904 observed time-resolved spectra, as well as with their time-integrated spectra and light curves. Although GRB 080319B and GRB 050904 are at very different redshifts (z = 0.937 and z = 6.29, respectively), a value of α = −1.8 for both of them leads to a good agreement between the numerical simulations and the observed BAT light curves, time-resolved and timeintegrated spectra. Such a modified spectrum is also consistent with the observations of previously analyzed less energetic GRBs and reasons for this additional agreement are given. Perspectives for future low-energy missions are outlined.

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“…It is therefore essential that in looking for this effect the high-and lowenergy data be simultaneous. Using GRB 050904, we note that the BAT and XRT contemporaneous spectra have compatible power-law slopes, with uncertainties of ∼0.1 on their spectral indices (Cusumano et al 2007). Disregarding the relatively small flux and cross-calibration uncertainties, this similarity of the observed spectral slopes between the XRT and BAT yields a 3σ limit on the column density of N e ∼ N H ∼ 5 × 10 24 cm −2 .…”

Section: Discussionmentioning

confidence: 58%

“…Currently, we do not typically obtain simultaneous soft and hard X-ray detections of a GRB, though there are a few exceptions where the burst was long and the Swift response time short. A good example is, in fact, GRB 050904 where the spectrum of the late prompt phase is detected in the range 2-700 keV in the rest frame (Watson et al 2006;Cusumano et al 2007). …”

Section: Discussionmentioning

confidence: 99%

The metallicity of gamma-ray burst environments from high-energy observations

Watson

Laursen

2011

A&A

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Gamma-ray bursts (GRBs) and their early afterglows ionise their circumburst material. Only high-energy spectroscopy therefore, allows examination of matter close to the burst itself. Soft X-ray absorption allows an estimate to be made of the total column density in metals. The detection of the X-ray afterglow can also be used to place a limit on the total gas column along the line of sight based on the Compton scattering opacity. Such a limit would enable, for the first time, the determination of lower limits on the metallicity in the circumburst environments of GRBs. In this paper, we determine the limits that can be placed on the total gas column density in the vicinities of GRBs based on Compton scattering. We simulate the effects of Compton scattering on a collimated beam of high-energy photons passing through a shell of high column-density material to determine the expected lightcurves, luminosities, and spectra. We compare these predictions to observations, and determine what limits can be placed on the total gas column density. The smearing out of pulses in the lightcurve from Compton scattering is not likely to be observable, and its absence does not place strong constraints on the Compton depth. However, the distribution of observed luminosities of bursts allows us to place statistical, model-dependent limits that are typically 10 25 cm −2 for less luminous bursts, and as low as ∼10 24 cm −2 for the most luminous. By using the shape of the high-energy broadband spectrum, however, limits as low as ∼5 × 10 24 cm −2 can be placed on individual bursts, implying metallicity lower limits from X-and gamma-rays alone from 0 up to 0.01 Z/Z . At extremely high redshifts, this limit would be at least 0.02 Z/Z , enough to distinguish population III from non-primordial GRBs.

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Swift observations of GRB 050904: the most distant cosmic explosion ever observed

Cited by 26 publications

References 66 publications

GRB 070311: a direct link between the prompt emission and the afterglow

GRB 070311: a direct link between the prompt emission and the afterglow

Analysis of GRB 080319b and GRB 050904 Within the Fireshell Model: Evidence for a Broader Spectral Energy Distribution

The metallicity of gamma-ray burst environments from high-energy observations

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