J/ApJ/788/30 Gamma-ray burst flares: X-ray flaring (Swenson+, 2014)
Gamma-ray burst flares: X-ray flaring. II.
Swenson C.A., Roming P.W.A.
<Astrophys. J., 788, 30 (2014)>
=2014ApJ...788...30S 2014ApJ...788...30S (SIMBAD/NED BibCode)
ADC_Keywords: Gamma rays ; Stars, flare ; X-ray sources ; Redshifts
Keywords: gamma-ray burst: general
Abstract:
We present a catalog of 498 flaring periods found in gamma-ray burst
(GRB) light curves taken from the online Swift X-Ray Telescope GRB
Catalogue (Evans et al. 2007A&A...469..379E 2007A&A...469..379E, 2009, J/MNRAS/397/1177).
We analyzed 680 individual light curves using a flare detection method
developed and used on our UV/optical GRB Flare Catalog. This method
makes use of the Bayesian Information Criterion to analyze the
residuals of fitted GRB light curves and statistically determines the
optimal fit to the light curve residuals in an attempt to identify any
additional features. These features, which we classify as flares, are
identified by iteratively adding additional "breaks" to the light
curve. We find evidence of flaring in 326 of the analyzed light
curves. For those light curves with flares, we find an average number
of ∼1.5 flares per GRB. As with the UV/optical, flaring in our sample
is generally confined to the first 1000 s of the afterglow, but can be
detected to beyond 105 s. Only ∼50% of the detected flares follow
the "classical" definition of Δt/t≤0.5, with many of the
largest flares exceeding this value.
Description:
For the purposes of this study, we will use the publicly available XRT
light curves from the online Swift-XRT GRB Catalogue (Evans et al.
2007A&A...469..379E 2007A&A...469..379E; 2009, J/MNRAS/397/1177). We downloaded the light
curves for the time period covering 2005 January through 2012
December, as well as the best-fit parameters for each burst. We
calculated the light curve residuals using the best-fit parameters and
perform our flare-finding analysis on these residuals.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 72 498 X-ray Flares
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See also:
J/MNRAS/397/1177 : Swift-XRT observations of GRBs (Evans+, 2009)
J/ApJS/209/20 : Swift GRB catalog with X-ray data (Grupe+, 2013)
J/MNRAS/428/729 : GRB Swift X-ray light curves analysis (Margutti+, 2013)
J/ApJS/224/20 : 10yr of Swift/XRT obs. of GRBs (Yi+, 2016)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1 A1 --- FP [Y/N] Flaring Period observed; Y/N
3- 12 A10 --- Name Source name (GRB YYMMDDA) (1)
14- 19 F6.4 --- z ? Redshift
21- 29 F9.2 s Tpeak Flare peak time (2)
31- 39 F9.2 s Tstart Lower limit on flare start time (2)
41- 50 F10.2 s Tstop Upper limit on flare stop time (2)
52- 57 F6.2 --- Delt/t The (Tstop-Tstart)/Tpeak ratio
59- 65 F7.2 --- FRatio Flux ratio (3)
67- 72 F6.4 --- Conf Confidence measure (4)
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Note (1): Flares are listed in chronological order by GRB date,
then sorted by confidence.
Note (2): Our analysis identifies a specific data point in the light curve as
being associated with these quantities. The large number of digits
reported for Tpeak, Tstart and Tstop are not reflective of our
confidence in their determination, but are rather the timestamp
associated with the data point identified. We have chosen not to
round these values for two reasons: 1) any rounding decision we make
would be arbitrary, and 2) the relative effect of the rounding on
each value would differ depending on the size of the value. This
also prevents the introduction of an arbitrary bias to the data. All
times are relative to the time of the initial burst trigger.
Note (3): Calculated as the flux at the flare peak time divided by the
extrapolated flux of the underlying light curve at the same time,
normalized using the flux of the underlying light curve, and is a
lower limit of the actual peak flux ratio.
Note (4): Represents the fraction of times the flare was identified during the
10000 Monte Carlo simulations. The first column identifies whether
the identified feature comes from an overlapping `flaring period'.
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History:
From electronic version of the journal
References:
Swenson et al., Paper I, 2013ApJ...774....2S 2013ApJ...774....2S
(End) Prepared by [AAS], Tiphaine Pouvreau [CDS] 03-Jul-2017