Comprehensive study of the X-ray flares from gamma-ray bursts observed by Swift

TL;DR

This comprehensive analysis of 468 X-ray flares from GRBs observed by Swift reveals their statistical properties, correlations, and potential physical origins, suggesting a Poynting-flux dominated jet model and self-organized criticality behavior.

Contribution

The study provides the largest catalog of GRB X-ray flares with detailed parameter analysis and links their distributions to self-organized criticality models, offering insights into their physical mechanisms.

Findings

Peak luminosity decreases with peak time following a power-law.

Flare durations increase with peak time.

Energy and duration distributions follow power-law behaviors.

Abstract

X-ray flares are generally supposed to be produced by the later central engine activities, and may share the similar physical origin with prompt emission of gamma-ray bursts (GRBs). In this paper, we have analyzed all significant X-ray flares from the GRBs observed by {\em Swift} from April 2005 to March 2015. The catalog contains 468 bright X-ray flares, including 200 flares with redshifts. We obtain the fitting results of X-ray flares, such as start time, peak time, duration, peak flux, fluence, peak luminosity, and mean luminosity. The peak luminosity decreases with peak time, following a power-law behavior $L_p \propto T_{peak,z}^{-1.27}$. The flare duration increases with peak time. The 0.3-10 keV isotropic energy of X-ray flares distribution is a lognormal peaked at $10^{51.2}$ erg. We also study the frequency distributions of flare parameters, including energies, durations, peak fluxes, rise times, decay times and waiting times. Power-law distributions of energies, durations, peak fluxes, and waiting times are found in GRB X-ray flares and solar flares. These distributions could be well explained by a fractal-diffusive, self-organized criticality model. Some theoretical models basing on magnetic reconnection have been proposed to explain X-ray flares. Our result shows that the relativistic jets of GRBs may be Poynting-flux dominated.