J/ApJ/756/112 Fermi/GBM GRB time-resolved spectral analysis (Lu+, 2012)
A comprehensive analysis of Fermi gamma-ray burst data.
II. Ep evolution patterns and implications for the observed
spectrum-luminosity relations.
Lu R.-J., Wei J.-J., Liang E.-W., Zhang B.-B., Lu H.-J., Lu L.-Z.,
Lei W.-H., Zhang B.
<Astrophys. J., 756, 112 (2012)>
=2012ApJ...756..112L 2012ApJ...756..112L
ADC_Keywords: Gamma rays
Keywords: gamma-ray burst: general; methods: statistical;
radiation mechanisms: non-thermal
Abstract:
We present a time-resolved spectral analysis of 51 long and 11 short
bright gamma-ray bursts (GRBs) observed with the Fermi/Gamma-Ray Burst
Monitor, paying special attention to Ep evolution within each burst.
Among eight single-pulse long GRBs, five show an evolution from hard
to soft, while three show intensity tracking. The multi-pulse long
GRBs have more complicated patterns. Statistically, the hard-to-soft
evolution pulses tend to be more asymmetric than the
intensity-tracking ones, with a steeper rising wing than the falling
wing. Short GRBs have Ep tracking intensity exclusively with the
16ms time-resolution analysis. We performed a simulation analysis and
suggest that for at least some bursts, the late intensity-tracking
pulses could be a consequence of overlapping hard-to-soft pulses.
However, the fact that the intensity-tracking pattern exists in the
first pulse of the multi-pulse long GRBs and some single-pulse GRBs,
suggests that intensity tracking is an independent component, which
may operate in some late pulses as well. For the GRBs with measured
redshifts, we present a time-resolved Ep-Lγ,iso correlation
analysis and show that the scatter of the correlation is comparable to
that of the global Amati/Yonetoku relation. We discuss the predictions
of various radiation models regarding Ep evolution, as well as the
possibility of a precessing jet in GRBs. The data pose a great
challenge to each of these models, and hold the key to unveiling the
physics behind GRB prompt emission.
Description:
We download the TTE (Time-Tagged Events) data from the NASA Fermi Web
site. The TTE event data files contain individual photons with time
and energy tags. We perform an extensive time-resolved spectral
analysis for the Fermi/GBM GRBs as of 2011 August 31 and build joint
fits to the spectra collected by the NaI (energy range from 8keV to
1MeV) and BGO (bismuth germanate; energies between 200keV and 40MeV)
detectors.
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
grb.dat 13 68 List of GRBs in the sample (table added by CDS)
table1.dat 82 982 Time-resolved spectral fits with the band function
for the GRBs in our sample
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See also:
IX/20 : The Fourth BATSE Burst Revised Catalog (Paciesas+ 1999)
J/A+A/557/A100 : Fermi and Swift GRBs Epeak-Eiso relation (Heussaff+, 2013)
J/ApJS/208/21 : The BATSE 5B GRB spectral catalog (Goldstein+, 2013)
J/ApJS/207/39 : IPN supplement to the Fermi GBM (Hurley+, 2013)
J/ApJS/199/18 : The Fermi GBM catalog (Paciesas+, 2012)
J/ApJ/754/121 : GRBs from Fermi/GBM and LAT (The Fermi Team, 2012)
J/ApJ/740/104 : BATSE GRB pulse catalog - preliminary data (Hakkila+, 2011)
J/A+A/530/A21 : Spectral properties of 438 GRBs (Nava+, 2011)
J/A+A/525/A53 : GBM parameters for detected FERMI bursts (Guetta+, 2011)
J/ApJ/720/1146 : Spectral analysis of GRBs (Lu+, 2010)
J/ApJS/166/298 : Spectral cat. of bright BATSE gamma-ray bursts (Kaneko+, 2006)
J/ApJ/609/935 : Gamma-ray burst formation rate (Yonetoku+, 2004)
J/ApJS/126/19 : BATSE gamma-ray burst spectral catalog. I. (Preece+, 2000)
http://fermi.gsfc.nasa.gov/ssc/data/access : Fermi SSC home page
ftp://legacy.gsfc.nasa.gov/fermi/data : Fermi data access
Byte-by-byte Description of file: grb.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- --- [GRB]
5- 11 A7 --- GRB GRB identifier (YYMMDDA)
13 A1 --- n_GRB [LS ] L=long GRB (see figure 2);
S=short GRB (see figure 3)
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Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 --- GRB GRB identifier (YYMMDDA)
9- 10 I2 --- Nz [1/44] Slice number
12- 18 F7.3 s Tbeg [-13/185] Start time
20- 26 F7.3 s Tend [-4./189] End time
28- 33 F6.1 keV Ep [5.8/6889] Peak energy of the spectrum
35- 40 F6.1 keV e_Ep [0/1003] Uncertainty in Ep
42- 46 F5.2 --- alpha [-1.8/2.2] Low energy photon spectral index
48- 51 F4.2 --- e_alpha [0/1.5] Uncertainty in alpha
53- 58 F6.2 --- beta [-13.2/-1.2] High energy photon spectral index
60- 63 F4.2 --- e_beta [0/1.5] Uncertainty in beta
65- 70 F6.2 nJ/m2 Flu [0.02/272] Fluence in 10-1000keV band;
in 10-6erg/cm2 unit
72- 75 F4.2 nJ/m2 e_Flu [0.01/2] Uncertainty in Flu
77- 82 F6.2 --- chi2 Model reduced χ2
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History:
From electronic version of the journal
References:
Zhang et al. Paper I. 2011ApJ...730..141Z 2011ApJ...730..141Z
Qin et al. Paper III. 2013ApJ...763...15Q 2013ApJ...763...15Q Cat. J/ApJ/763/15
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 26-Mar-2014