J/ApJ/777/132 A search for progenitors of short GRBs (Dichiara+, 2013)
A search for pulsations in short gamma-ray bursts to constrain their
progenitors.
Dichiara S., Guidorzi C., Frontera F., Amati L.
<Astrophys. J., 777, 132 (2013)>
=2013ApJ...777..132D 2013ApJ...777..132D
ADC_Keywords: Gamma rays
Keywords: accretion, accretion disks; gamma-ray burst: general;
methods: data analysis; techniques: photometric
Abstract:
We searched for periodic and quasi-periodic signals in the prompt
emission of a sample of 44 bright short gamma-ray bursts (GRBs)
detected with Fermi/GBM, Swift/BAT, and CGRO/BATSE. The aim was to
look for the observational signature of quasi-periodic jet precession,
which is expected from black hole (BH)-neutron star (NS) mergers, but
not from double NS systems. Thus, this kind of search holds the key to
identifying the progenitor systems of short GRBs and, in the interim
before gravitational wave detectors become on-lines, represents the
only direct way to constrain the progenitors. We tailored our search
to the nature of the expected signal by properly stretching the
observed light curves by an increasing factor with time, after
calibrating the technique with synthetic curves. None of our GRBs
showed evidence for periodic or quasi-periodic signals. In particular,
for the seven unambiguously short GRBs with the best signal-to-noise
ratios, we obtained significant upper limits to the amplitude of the
possible oscillations. This result suggests that BH-NS systems do not
dominate the population of short GRB progenitors, as described by the
kinematic model of Stone et al. (2013PhRvD..87h4053S 2013PhRvD..87h4053S).
Description:
We took all the events observed by the Fermi/GBM from 2008 July to
2012 December. We selected the SGRBs by requiring T90<3s, and ended
up with 160 GRBs, 18 of which have a minimum signal-to-noise ratio
(S/N) of 20, as computed over the T5σ interval. See section 2.1
The same selection criteria were applied to the Swift/BAT sample using
all the events detected up to early 2013 June (12 GRBs selected).
14 SGRBs whose profiles were extracted in the 20-2000keV energy range
were selected from BATSE/CGRO (Paciesas+, 1999, IX/20).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 152 74 Best-fitting model and parameters for each 44 short
duration gamma-ray burst (SGRB) of the total sample
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See also:
IX/20 : The Fourth BATSE Burst Revised Catalog (Paciesas+ 1999)
J/ApJS/216/32 : Localizations of GRBs with Fermi GBM (Connaughton+, 2015)
J/ApJS/211/13 : The second Fermi/GBM GRB catalog (4yr) (von Kienlin+, 2014)
J/ApJS/208/21 : The BATSE 5B GRB spectral catalog (Goldstein+, 2013)
J/ApJS/207/38 : IPN localizations of Konus short GRBs (Pal'shin+, 2013)
J/MNRAS/431/3608 : BeppoSAX/GRBM and Fermi/GBM long GRBs (Dichiara+, 2013)
J/ApJS/207/39 : IPN supplement to the Fermi GBM (Hurley+, 2013)
J/ApJ/756/112 : Fermi/GBM GRB time-resolved spectral analysis (Lu+, 2012)
J/ApJ/748/134 : Variability in BATSE GRB light curves (Gao+, 2012)
J/ApJS/199/18 : The Fermi GBM catalog (Paciesas+, 2012)
J/ApJS/195/2 : The second Swift BAT GRB catalog (BAT2) (Sakamoto+, 2011)
J/A+A/525/A53 : GBM parameters for detected FERMI bursts (Guetta+, 2011)
J/ApJ/740/104 : BATSE GRB pulse catalog - preliminary data (Hakkila+, 2011)
J/ApJ/711/495 : Durations of Swift/BAT GRBs (Butler+, 2010)
J/ApJS/134/385 : Supplement to the BATSE GRB catalogs (Kommers+, 2001)
J/ApJ/508/314 : Gamma-ray bursts types (Mukherjee+, 1998)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- GRB Gamma-ray Burst identifier (YYMMDDA)
10 A1 --- r_GRB [d-f] Detection origin (1)
12- 14 A3 --- Mod Best PDS fit model: "pl" or "bpl" (2)
16- 20 F5.3 [-] logN [0.9/5.3] Log of Power Density Spectrum (PDS)
normalization (2)
22- 26 F5.3 [-] e_logN [0.1/1.5] Lower 90% confidence level on logN
28- 32 F5.3 [-] E_logN [0.1/7.8] Upper 90% confidence level on logN
34- 39 F6.3 [Hz] logfb [-0.8/1.5]? Log of PDS frequency break parameter
fb (2)
41- 45 F5.3 [Hz] e_logfb [0.09/5]? Lower 90% confidence level on logfb
47- 51 F5.3 [Hz] E_logfb [0.08/0.9]? Upper 90% confidence level on logfb
53- 57 F5.3 --- alpha [0.8/6.8] PDS slope α (2)
59- 63 F5.3 --- e_alpha [0.1/3] Lower 90% confidence level on alpha
65- 69 F5.3 --- E_alpha [0.1/7] Upper 90% confidence level on alpha
71- 75 F5.3 --- B [1.5/2.5] White (poissoinian) noise level parameter
77- 81 F5.3 --- e_B [0.05/1.3] Lower 90% confidence level on B
83- 87 F5.3 --- E_B [0.05/1] Upper 90% confidence level on B
89- 93 F5.3 --- pTR [0.01/1] Significance associated to TR statistic
95- 99 F5.3 --- pAD [0.1/1] Significance of the Anderson-Darling test
101-105 F5.3 --- pKS [0.1/1] Significance of the Kolmogorov-Smirnov test
107-111 F5.3 --- Ratio [0.006/0.6] Ratio of Pulse amplitude
A2σ/Apeak
113-117 F5.3 s T90 [0.1/2.7] Burst duration
119-124 F6.3 s t0 [-3/0.03] Start time t0
126-131 F6.3 s t1 [0.1/3] Stop time t1
133 A1 --- f_HR [h] ODS extraction > T5σ (3)
135-140 F6.3 --- HR [0.6/10.8] Hardness ratio (4)
142-146 F5.3 --- e_HR [0.07/1.1] The 1σ confidence level in HR
148-152 F5.3 --- pSh [0.006/1] Probability of belonging to short
class of GRB
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Note (1): Flag as follows:
d = Detected by Swift/BAT (24 rows, 12 GRBs);
e = Detected by Fermi/GBM (36 rows, 18 GRBs);
f = Detected by CGRO/BATSE (14 GRBs).
Note (2): We studied the power density spectrum (PDS) of each light curve
in two different ways. PDSs were calculated adopting the Leahy
normalization (Leahy et al. 1983ApJ...266..160L 1983ApJ...266..160L). To fit the PDSs, we
used the technique set up by Vaughan (2010MNRAS.402..307V 2010MNRAS.402..307V) based on a
Bayesian treatment with Markov Chain Monte Carlo techniques. Two
analytical models were assumed to describe the PDS continuum (section 3):
* a simple power-law plus constant (pl) [Equation (1)]:
SPL(f)=N.f-α+B
* or a broken power-law plus constant (bpl) [Equation (2)] with
low-frequency index fixed to zero:
SBPL(f)=N[1+(f/fb)α]-1+B
Note (3): In this case the time interval of PDS extraction is larger then the
T5σ interval to fit properly the continuum shape.
Note (4): Hardness ratio is defined as the fluence ratios:
* S(50-100keV)/S(25-50keV) for Swift/BAT
* S(100-300keV)/S(50-100keV) for Fermi/GBM and CGRO/BATSE
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 09-Apr-2015