Unveiling the origin of X-ray flares in gamma-ray bursts

By G. Chincarini, J. Mao, Raffaella Margutti, M. Bernardini, C. Guidorzi, F. Pasotti, D. Giannios, M. Della Valle, Alessia Moretti, P. Romano and 3 more. 2010

149 citations recorded by the source corpus.

We present an updated catalogue of 113 X-ray flares detected by Swift in the similar to 33 per cent of the X-ray afterglows of gamma-ray burst (GRB). 43 flares have a measured redshift. For the first time the analysis is performed in four different X-ray energy bands, allowing us to constrain the evolution of the flare temporal properties with energy. We find that flares are narrower at higher energies: their width follows a power-law relation w proportional to E-0.5 reminiscent of the prompt emission. Flares are asymmetric structures, with a decay time which is twice the rise time on average. Both time-scales linearly evolve with time, giving rise to a constant rise-to-decay ratio: this implies that both time-scales are stretched by the same factor. As a consequence, the flare width linearly evolves with time to larger values: this is a key point that clearly distinguishes the flare from the GRB prompt emission. The flare 0.3-10 keV peak luminosity decreases with time, following a power-law behaviour with large scatter: L(pk) proportional to t-2.7 +/- 0.5(pk). When multiple flares are present, a global softening trend is established: each flare is on average softer than the previous one. The 0.3-10 keV isotropic energy distribution is a lognormal peaked at 1051 erg, with a possible excess at low energies. The flare average spectral energy distribution is found to be a power law with spectral energy index beta similar to 1.1. These results confirmed that the flares are tightly linked to the prompt emission. However, after considering various models we conclude that no model is currently able to account for the entire set of observations.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/d7349f186fcb72f38c4428e1dfe82f01beb41eb8

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In Astronomy and Astrophysics

1. Bing Zhang
2. B. Metzger
3. E. Berger
4. E. Quataert
5. Pawan Kumar
6. T. Thompson
7. Xuefeng Wu
8. W. Lei

In Instrumentation

1. Bing Zhang
2. Pawan Kumar
3. E. Quataert
4. B. Metzger
5. D. Burrows
6. T. Thompson
7. C. Guidorzi
8. E. Berger

Citations in the corpus

• The physics of gamma-ray bursts & relativistic jets (2014, methodology): “Further, more detailed, modeling (Wu et al., 2006; Lazzati and Perna, 2007; Maxham and Zhang, 2009) and data analysis (Chincarini et al., 2010; Margutti et al., 15 This model predicts a quasi-thermal spectrum, which may interpret spectral softening during the X-ray tails.”
• The prompt-afterglow connection in gamma-ray bursts: a comprehensive statistical analysis of Swift X-ray light curves (2012, background): “…Grupe et al. 2007); it cannot account for abrupt drops of emission observed in some GRBs (e.g. GRB070110, Troja et al. 2007, Lyons et al. 2010) and has serious difficulties explaining the X-ray flares (Chincarini et al. 2007, Falcone et al. 2007; Chincarini et al. 2010 and references therein).”
• Short-Duration Gamma-Ray Bursts (2013, background): “…exponential decay profile with∆t/t ≪ 1, and share spectral and temporal properties with the prompt emission, pointingto a common origin in activity from the central engine (Chincarini et al. 2010, Margutti et al. 2010); here,∆t is the flare duration andt is the time since the onset of the burst.”
• A complete reference of the analytical synchrotron external shock models of gamma-ray bursts (2013, methodology): “Systematic data analyses (Zhang et al., 2007; Liang et al., 2007, 2008, 2009; Butler and Kocevski, 2007; Kocevski et al., 2007; Chincarini et al., 2007, 2010; Margutti et al., 2010) suggest that the X-ray afterglow is a superposition of the conventional external shock component and a radiation…”
• The Proto-Magnetar Model for Gamma-Ray Bursts (2010, background): “Superimposed on the smoother afterglow are large amplitude X-ray flares (Piro et al. 2005; Burrows et al. 2005, 2007; Chincarini et al. 2007; Chincarini et al. 2010), which share many properties with the prompt GRB emission (Margutti et al. 2010) and also appear to result from late-time central…”