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Title: GRB 060714: No Clear Dividing Line Between Prompt Emission and X-Ray Flares

Abstract

The long gamma-ray burst GRB 060714 was observed to exhibit a series of five X-ray flares beginning {approx} 70 s after the burst trigger T{sub 0} and continuing until {approx} T{sub 0} + 200 s. The first two flares were detected by the Burst Alert Telescope (BAT) on the Swift satellite, before Swift had slewed to the burst location, while the last three flares were strongly detected by the X-Ray Telescope (XRT) but only weakly detected by the BAT. This burst provides an unusual opportunity to track a complete sequence of flares over a wide energy range. The flares were very similar in their light curve morphology, showing power-law rise and fall components, and in most cases significant sub-structure. The flares also showed strong evolution with time, both spectrally and temporally. The small time scale and large amplitude variability observed are incompatible with an external shock origin for the flares, and support instead late time sporadic activity either of the central source or of localized dissipation events within the outflow. We show that the flares in GRB 060714 cannot be the result of internal shocks in which the contrast in the Lorentz factor of the colliding shells is very small,more » and that this mechanism faces serious difficulties in most Swift GRBs. The morphological similarity of the flares and the prompt emission and the gradual and continual evolution of the flares with time makes it difficult and arbitrary to draw a dividing line between the prompt emission and the flares.« less

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Stanford Linear Accelerator Center (SLAC)
Sponsoring Org.:
USDOE
OSTI Identifier:
900237
Report Number(s):
SLAC-PUB-12368
astro-ph/0702603; TRN: US200709%%470
DOE Contract Number:
AC02-76SF00515
Resource Type:
Journal Article
Resource Relation:
Journal Name: Submitted to Astrophysical Journal
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; COSMIC GAMMA BURSTS; ENERGY RANGE; ORIGIN; TELESCOPES; X RADIATION; Astrophysics,ASTRO

Citation Formats

Krimm, Hans A., /NASA, Goddard /Universities Space Research Assoc., Granot, J., /KIPAC, Menlo Park, Marshal, F., /NASA, Goddard, Perri, M., /ASDC, Frascati, Barthelmy, S.D., /NASA, Goddard, Burrows, D.N., /Penn State U., Astron. Astrophys., Gehrels, N., /NASA, Goddard, Meszaros, P., Morris, D., and /Penn State U., Astron. Astrophys.. GRB 060714: No Clear Dividing Line Between Prompt Emission and X-Ray Flares. United States: N. p., 2007. Web. doi:10.1086/519019.
Krimm, Hans A., /NASA, Goddard /Universities Space Research Assoc., Granot, J., /KIPAC, Menlo Park, Marshal, F., /NASA, Goddard, Perri, M., /ASDC, Frascati, Barthelmy, S.D., /NASA, Goddard, Burrows, D.N., /Penn State U., Astron. Astrophys., Gehrels, N., /NASA, Goddard, Meszaros, P., Morris, D., & /Penn State U., Astron. Astrophys.. GRB 060714: No Clear Dividing Line Between Prompt Emission and X-Ray Flares. United States. doi:10.1086/519019.
Krimm, Hans A., /NASA, Goddard /Universities Space Research Assoc., Granot, J., /KIPAC, Menlo Park, Marshal, F., /NASA, Goddard, Perri, M., /ASDC, Frascati, Barthelmy, S.D., /NASA, Goddard, Burrows, D.N., /Penn State U., Astron. Astrophys., Gehrels, N., /NASA, Goddard, Meszaros, P., Morris, D., and /Penn State U., Astron. Astrophys.. Mon . "GRB 060714: No Clear Dividing Line Between Prompt Emission and X-Ray Flares". United States. doi:10.1086/519019. https://www.osti.gov/servlets/purl/900237.
@article{osti_900237,
title = {GRB 060714: No Clear Dividing Line Between Prompt Emission and X-Ray Flares},
author = {Krimm, Hans A. and /NASA, Goddard /Universities Space Research Assoc. and Granot, J. and /KIPAC, Menlo Park and Marshal, F. and /NASA, Goddard and Perri, M. and /ASDC, Frascati and Barthelmy, S.D. and /NASA, Goddard and Burrows, D.N. and /Penn State U., Astron. Astrophys. and Gehrels, N. and /NASA, Goddard and Meszaros, P. and Morris, D. and /Penn State U., Astron. Astrophys.},
abstractNote = {The long gamma-ray burst GRB 060714 was observed to exhibit a series of five X-ray flares beginning {approx} 70 s after the burst trigger T{sub 0} and continuing until {approx} T{sub 0} + 200 s. The first two flares were detected by the Burst Alert Telescope (BAT) on the Swift satellite, before Swift had slewed to the burst location, while the last three flares were strongly detected by the X-Ray Telescope (XRT) but only weakly detected by the BAT. This burst provides an unusual opportunity to track a complete sequence of flares over a wide energy range. The flares were very similar in their light curve morphology, showing power-law rise and fall components, and in most cases significant sub-structure. The flares also showed strong evolution with time, both spectrally and temporally. The small time scale and large amplitude variability observed are incompatible with an external shock origin for the flares, and support instead late time sporadic activity either of the central source or of localized dissipation events within the outflow. We show that the flares in GRB 060714 cannot be the result of internal shocks in which the contrast in the Lorentz factor of the colliding shells is very small, and that this mechanism faces serious difficulties in most Swift GRBs. The morphological similarity of the flares and the prompt emission and the gradual and continual evolution of the flares with time makes it difficult and arbitrary to draw a dividing line between the prompt emission and the flares.},
doi = {10.1086/519019},
journal = {Submitted to Astrophysical Journal},
number = ,
volume = ,
place = {United States},
year = {Mon Feb 26 00:00:00 EST 2007},
month = {Mon Feb 26 00:00:00 EST 2007}
}
  • From a sample of gamma-ray bursts (GRBs) detected by the Fermi and Swift missions, we have extracted the minimum variability timescales for temporal structures in the light curves associated with the prompt emission and X-ray flares. A comparison of this variability timescale with pulse parameters such as rise times, determined via pulse-fitting procedures, and spectral lags, extracted via the cross-correlation function, indicates a tight correlation between these temporal features for both the X-ray flares and the prompt emission. These correlations suggest a common origin for the production of X-ray flares and the prompt emission in GRBs.
  • Recently, the GeV radiation during the X-ray flare activity in GRB 100728A was detected by Fermi/LAT. Here, we study the dynamics and emission properties of a collision between two homogeneous shells based on the late internal shock model. The GeV photons can be produced from X-ray flare photons being upscattered by relativistic electrons that are accelerated by forward-reverse shocks, where the involved radiative processes include synchrotron self-Compton and crossing inverse-Compton scattering. Using analytical and numerical calculations, the observed spectral properties in GRB 100728A can be well explained.
  • We jointly analyze the gamma-ray burst (GRB) data observed with Burst Alert Telescope (BAT) and X-ray Telescope on board the Swift mission to present a global view on the internal energy dissipation processes in GRBs, including precursors, prompt gamma-ray emission, extended soft gamma-ray emission, and late X-ray flares. The Bayesian block method is utilized to analyze the BAT light curves to identify various emission episodes. Our results suggest that these emission components likely share the same physical origin, which is the repeated activation of the GRB central engine. What we observe in the gamma-ray band may be a small partmore » of more extended underlying activities. The precursor emission, which is detected in about 10% of Swift GRBs, is preferably detected in those GRBs that have a massive star core-collapse origin. The soft extended emission tail, on the other hand, is preferably detected in those GRBs that have a compact star merger origin. Bright X-ray emission is detected during the BAT quiescent phases prior to subsequent gamma-ray peaks, implying that X-ray emission may be detectable prior the BAT trigger time. Future GRB alert instruments with soft X-ray capability are essential for revealing the early stages of GRB central engine activities, and shedding light on jet composition and the jet launching mechanism in GRBs.« less
  • We argue that the dominant radiation mechanism responsible for the early prompt {gamma}-rayemission of gamma-ray bursts could be the resonant inverse Compton scattering(RICS) of relativistic electrons in an intense magnetic field. By using this mechanism, some problems in the GRB study could be clarified, e.g., the origin of the Amati relation, the formation of the observed broken power law spectra, and the related 'deadline problem', the solution of the 'compactness problem', etc.. Our model also predicts that the emitted {gamma}-rayscould be highly polarized.