P-352

Ferrero, Simone; Capellino, Silvia; Schubert, Tilman; Ragni, Nicola; Remorgida, Valentino; Straub, R.H.

doi:10.1016/j.fertnstert.2006.07.708

Cited by 1 publication

(1 citation statement)

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“…All four segments of this burst can be adequately characterized by the closure relations: segment I is consistent with the high latitude relation; segment II requires p > 2 and energy injection, but is consistent with either slow or fast cooling and either ISM or wind environment; segment III is consistent with either isotropic or jet-with-energy-injection relations; and segment IV is consistent with either a spreading or non-spreading jet with an ISM or wind environment. The resulting fits imply that the jet break time cannot be unambiguously established; if the II-III break is due to the cessation of energy injection then the III-IV break is a jet break, but it is also possible that the II-III break is the jet break and the III-IV break is due to the end of energy injection (see also Ferrero et al 2008 for a similar analysis of this GRB). We list the properties of the Prominent jet break bursts in Table 2.…”

Section: Prominent Jet Break Classmentioning

confidence: 99%

JET BREAKS AND ENERGETICS OFSwiftGAMMA-RAY BURST X-RAY AFTERGLOWS

Racusin

Liang

Burrows

et al. 2009

ApJ

312

397

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We present a systematic temporal and spectral study of all Swift -XRT observations of GRB afterglows discovered between 2005 January and 2007 December. After constructing and fitting all light curves and spectra to power-law models, we classify the components of each afterglow in terms of the canonical X-ray afterglow and test them against the closure relations of the forward shock models for a variety of parameter combinations. The closure relations are used to identify potential jet breaks with characteristics including the uniform jet model with and without lateral spreading and energy injection, and a power-law structured jet model, all with a range of parameters. With this technique, we survey the X-ray afterglows with strong evidence for jet breaks (∼ 12% of our sample), and reveal cases of potential jet breaks that do not appear plainly from the light curve alone (another ∼ 30%), leading to insight into the missing jet break problem. Those X-ray light curves that do not show breaks or have breaks that are not consistent with one of the jet models are explored to place limits on the times of unseen jet breaks. The distribution of jet break times ranges from a few hours to a few weeks with a median of ∼ 1 day, similar to what was found pre-Swift. On average Swift GRBs have lower isotropic equivalent γ-ray energies, which in turn results in lower collimation corrected γ-ray energies than those of pre-Swift GRBs. Finally, we explore the implications for GRB jet geometry and energetics.The power-law structured jet relations are valid for a particular α and β provided the

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Section: Prominent Jet Break Classmentioning

confidence: 99%