Methods and results of an automatic analysis of a complete sample of Swift-XRT observations of GRBs

By P. Evans, A. Beardmore, K. Page, J. Osborne, P. O’Brien, R. Willingale, R. Starling, D. Burrows, O. Godet, L. Vetere and 15 more. 2008

1,264 citations recorded by the source corpus.

We present a homogeneous X-ray analysis of all 318 gamma-ray bursts detected by the X-ray telescope (XRT) on the Swift satellite up to 2008 July 23; this represents the largest sample of X-ray GRB data published to date. In Sections 2-3, we detail the methods which the Swift-XRT team has developed to produce the enhanced positions, light curves, hardness ratios and spectra presented in this paper. Software using these methods continues to create such products for all new GRBs observed by the Swift-XRT. We also detail web-based tools allowing users to create these products for any object observed by the XRT, not just GRBs. In Sections 4-6, we present the results of our analysis of GRBs, including probability distribution functions of the temporal and spectral properties of the sample. We demonstrate evidence for a consistent underlying behaviour which can produce a range of light-curve morphologies, and attempt to interpret this behaviour in the framework of external forward shock emission. We find several difficulties, in particular that reconciliation of our data with the forward shock model requires energy injection to continue for days to weeks.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/9e774561ac841e4919f50ae3d49b9539a23fcb27

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Citations in the corpus

• The SUrvey for Pulsars and Extragalactic Radio Bursts – II. New FRB discoveries and their follow-up. (2017, methodology): “The data were analysed using the tools available at the Swift website (Evans et al. 2007, 2009) on an observation-by-observation basis.”
• The nature of "dark" gamma-ray bursts (2010, methodology): “The X-ray spectra were flux normalized to the epoch corresponding to the GROND observations using the XRT light curves from Evans et al. (2007, 2009).”
• A CONTINUUM OF H- TO He-RICH TIDAL DISRUPTION CANDIDATES WITH A PREFERENCE FOR E+A GALAXIES (2014, methodology): “Data obtained by the on-board X-Ray Telescope (XRT; Burrows et al. 2005) was analyzed with the automated gamma-ray burst pipeline outlined in Evans et al. (2009).”
• The prompt-afterglow connection in gamma-ray bursts: a comprehensive statistical analysis of Swift X-ray light curves (2012, background): “…While agreeing on the major steps, the data extraction adopted here is slightly different from the methods presented in Evans et al. (2007) and Evans et al. (2009): however, after comparing every single LC obtained with the two techniques, we find that the methods lead to consistent results.”
• THE THIRD SWIFT BURST ALERT TELESCOPE GAMMA-RAY BURST CATALOG (2015, methodology): “We further compare these late-time emissions to the Swift/ XRT light curves generated by the Burst Analyser41 (Evans et al. 2010, 2009, 2007).”
• Unveiling the origin of X-ray flares in gamma-ray bursts (2010, background): “These phases can be either all or in part present (Evans et al. 2009).”
• A DECADE OF SHORT-DURATION GAMMA-RAY BURST BROADBAND AFTERGLOWS: ENERGETICS, CIRCUMBURST DENSITIES, AND JET OPENING ANGLES (2015, methodology): “…2.3×104 354 0.36 0.093 2.3×104 461 0.27 0.070 2.8×104 354 0.23 0.057 2.8×104 253 0.30 0.077 2.9×104 366 0.20 0.054 3.1×104 5.1×103 0.18 0.033 4.2×104 6.0×103 0.13 0.034 4.6×104 479 0.21 0.052 5.4×104 6.5×103 0.080 0.018 6.8×104 1.2×104 0.076 0.0142 1.2×105 8.6×104 0.029 6.5×10−3 2.6×105 5.8×104 <…”
• SPACE TELESCOPE AND OPTICAL REVERBERATION MAPPING PROJECT. II. SWIFT AND HST REVERBERATION MAPPING OF THE ACCRETION DISK OF NGC 5548 (2015, positive): “XRT data reduction The Swift XRT data were gathered in photon counting (PC) mode and analyzed using the tools described by Evans et al. (2009)44 to produce light curves which are fully corrected for instrumental effects such as pile up, dead regions on the CCD and vignetting.”
• The unusual X-ray emission of the short Swift GRB 090515: evidence for the formation of a magnetar? (2010, methodology): “Additionally, the final decay is the steepest decay observed to date (Evans et al. 2009).”
• The physics of gamma-ray bursts & relativistic jets (2014, background): “This rapid decline is seen in the majority of GRBs (Evans et al., 2009; Liang et al., 2009) and heralds the winding down of central engine activity 38 .”
• A complete reference of the analytical synchrotron external shock models of gamma-ray bursts (2013, background): “…detect the early phase of the GRB X-ray afterglow, which shows some un-predicted features (Tagliaferri et al., 2005; Burrows et al., 2005; Nousek et al., 2006; O’Brien et al., 2006; Evans et al., 2009) that demand multiple physical processes that shape the observed lightcurves (Zhang et al., 2006).”
• Swift J1112.2−8238: a candidate relativistic tidal disruption flare (2015, methodology): “We obtained reduced XRT products from the Swift archive2, created using the techniques outlined in Evans et al. (2007, 2009, 2010).”
• THE LIGHT CURVE OF THE MACRONOVA ASSOCIATED WITH THE LONG–SHORT BURST GRB 060614 (2015, methodology): “The simultaneous X-ray emission, retrieved from the UK Swift Science Data Centre (Evans et al. 2009), can be fitted by t−2.55 plus a constant flux.”
• On the generation of high-energy photons detected by the Fermi Satellite from gamma-ray bursts (2009, background): “This rapid decay in flux in the X-ray band has been observed in∼60% of all bursts detected by the Swift satellite (Evans et al. 2009).”
• Revisiting Optical Tidal Disruption Events with iPTF16axa (2017, methodology): “Using standard XRT analysis procedures (e.g., Evans et al. 2009), we place 90% confidence upper limits ranging from (2.9–12.0) × 10−3 counts s−1 in the 0.3– 10.0 keV bandpass over this time period.”
• The subarcsecond mid-infrared view of local active galactic nuclei – II. The mid-infrared–X-ray correlation (2015, methodology): “This work made use of data supplied by the UK Swift Science Data Centre at the University of Leicester.”