J/ApJ/862/155 Two-episode prompt emission of GRB with Fermi (Lan+, 2018)
Characteristics of two-episode emission patterns in Fermi long gamma-ray bursts.
Lan L., Lu H.-J., Zhong S.-Q., Zhang H.-M., Rice J., Cheng J.-G., Du S.-S.,
Li L., Lin J., Lu R.-J., Liang E.-W.
<Astrophys. J., 862, 155-155 (2018)>
=2018ApJ...862..155L 2018ApJ...862..155L (SIMBAD/NED BibCode)
ADC_Keywords: GRB
Keywords: gamma-ray burst: general; methods: statistical
Abstract:
Two-episode emission components separated by quiescent gaps in the
prompt emission of gamma-ray bursts (GRBs) have been observed in the
Swift era, but there is a lack of spectral information due to the
narrow energy band of the Swift/Burst Alert Telescope. In this paper,
a systematic analysis of the spectral and temporal properties of the
prompt emission of 101 Fermi/Gamma-ray Burst Monitor detected long
GRBs show the existence of two-episode emission components in the
light curves, with quiescent times of up to hundreds of seconds. We
focus on investigating the differences of those two emission episodes.
We find that the light curves of the two emission components exhibit
different behavior, e.g., a soft emission component that either
precedes or follows the main prompt emission or that the intensity of
the two emission episodes are comparable with each other. No
statistically significant correlation in the duration of the two
emission episodes can be claimed. We define a new parameter ε
as the ratio of the peak flux of the first and second emission
episodes and find that a higher ε corresponds to a larger
fluence. The preferred spectral model in our analysis is a cutoff
power-law model for most GRBs. The distribution of Ep for episodes I
and II range from tens of keV to 1000 keV with a lognormal fit and
there are no significant differences between them. Moreover, we do not
find significant relationships between ε and Ep for the two
emission episodes. Those results suggest that these two-episode
emission components likely share the same physical origin.
Description:
We download the original Gamma-ray Burst Monitor (GBM) data (12 NaI
and 2 BGO detectors), as well as Large Area Telescope (LAT) data of
gamma-ray bursts (GRBs) from the public science support center at the
official Fermi website.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 122 101 Results of the temporal and spectral analysis
of 101 GRBs in our sample
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See also:
J/ApJ/720/1146 : Spectral analysis of GRBs (Lu+, 2010)
J/ApJ/754/121 : GRBs from Fermi/GBM and LAT (The Fermi Team, 2012)
J/ApJS/199/18 : The Fermi GBM catalog (Paciesas+, 2012)
J/ApJ/756/112 : Fermi/GBM GRB time-resolved spectral analysis (Lu+, 2012)
J/ApJ/763/15 : Fermi GRB analysis. III. T90 distributions (Qin+, 2013)
J/ApJ/787/66 : Burst duration measurements for a GRB sample (Zhang+, 2014)
J/ApJ/865/153 : Analysis of Fermi GRB data. IV. Spectral lags (Lu+, 2018)
J/ApJ/886/20 : Bayesian time-resolved spectra of Fermi GBM pulses (Yu+, 2019)
J/ApJ/893/46 : The 4th Fermi-GBM GRB catalog: 10 years (von Kienlin+, 2020)
J/ApJ/913/60 : GRB energetics from Fermi-GBM 10years (Poolakkil+, 2021)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Fermi Trigger ID (bnYYMMDDddd)
13- 17 F5.2 s TEI [0.4/80.3] Duration of the first emission
episode, TE,I
19- 24 F6.2 10-10W/m2 FpI [0.17/123] Flux of the first emission
episode in 10-7erg/cm2/s, Fp,I
26- 30 F5.2 10-10W/m2 e_FpI [0.05/21] FpI uncertainty
32- 37 F6.2 keV EpI [34/947] Peak energy of CPL model fits of
the first emission episode, Ep,I
39- 44 F6.2 keV e_EpI [1/235] EpI uncertainty
46- 49 F4.2 --- alpI [0.05/1.94] The low energy photon index of
CPL model fits for the first emission
episode, αI
51- 54 F4.2 --- e_alpI [0.01/0.3] alpI uncertainty
56- 58 I3 --- Chi2I [193/326] Fit χ2 for the first
emission episode
60- 62 I3 --- dofI [232/241] Dof for the first emission episode
64- 69 F6.2 s Tq [5.4/223.4] The quiescent times that are
calculated from the end of the first
episode to the beginning of the second
episode
71- 76 F6.2 s TEII [1.6/137] Duration of the second emission
episode, TE,II
78- 83 F6.2 10-10W/m2 FpII [0.98/167] Flux of the second emission
episode in 10-7erg/cm2/s, Fp,II
85- 89 F5.2 10-10W/m2 e_FpII [0.09/21] FpII uncertainty
91- 97 F7.2 keV EpII [18/1362] Peak energy of CPL model fits of
the second emission episode, Ep,II
99- 104 F6.2 keV e_EpII [2/440] EpII uncertainty
106- 109 F4.2 --- alpII [0.13/2.2] The low energy photon index of
CPL model fits for the second emission
episode, αII
111- 114 F4.2 --- e_alpII [0.01/0.4] alpII uncertainty
116- 118 I3 --- Chi2II [177/316] Fit χ2 for the second
emission episode
120- 122 I3 --- dofII [235/241] Dof for the second emission
episode
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 29-Sep-2023