J/A+A/690/A261 GRB variability-luminosity relationship (Guidorzi+, 2024)
New results on the gamma-ray burst variability-luminosity relationship.
Guidorzi C., Maccary R., Tsvetkova A., Kobayashi S., Amati L., Bazzanini L.,
Bulla M., Camisasca A. E., Ferro L., Frederiks D., Frontera F., Lysenko A.,
Maistrello M., Ridnaia A., Svinkin D., Ulanov M.
<Astron. Astrophys. 690, A261 (2024)>
=2024A&A...690A.261G 2024A&A...690A.261G (SIMBAD/NED BibCode)
ADC_Keywords: Gamma rays ; GRB
Keywords: methods: data analysis - methods: statistical -
gamma-ray burst: general
Abstract:
At the dawn of the gamma-ray burst (GRB) afterglow era, a Cepheid-like
correlation was discovered between the time variability V and the
isotropic-equivalent peak luminosity Liso of the prompt emission of
about a dozen long GRBs with measured redshift available at that time.
Soon afterwards, the correlation was confirmed in a sample of about 30
GRBs, even though it was affected by significant scatter. Unlike the
minimum variability timescale (MVT), V measures the relative power of
short-to-intermediate timescales.
We aim to test the correlation using about 200 long GRBs with
spectroscopically measured redshift, detected by Swift, Fermi, and
Konus/WIND, for which both observables can be accurately estimated.
The variability for all selected GRBs was calculated according to the
original definition using the 64 ms background subtracted light curves
of Swift/BAT (Fermi/GBM) in the 15-150 (8-900)keV energy passband.
Peak luminosities were either taken from the literature or derived
from modelling broad-band spectra acquired with either Konus/WIND or
Fermi/GBM.
The statistical significance of the correlation has weakened to ≲2%,
mostly due to the appearance of a number of smooth and luminous GRBs
that are characterised by a relatively small V. At odds with most long
GRBs, three out of four long-duration merger candidates have high V
and low Liso.
The luminosity is more tightly connected with shortest timescales
measured by MVT than the short to intermediate timescales measured by
V.We discuss the implications for internal dissipation models and the
role of the e photosphere.We identified a few smooth GRBs with a
single broad pulse and low V that might have an external shock origin,
in contrast with most GRBs. The combination of high variability
(V≳0.1), low luminosity Liso≲1051erg/s, and short MVT (≲0.1s)
could be a good indicator for a compact binary merger origin.
Description:
We report in the tables the values of variability and peak luminosity
for the merged sample of bursts with statistically significant
measures of both quantities. Table 1 reports variability calculated
assuming f=0.8,, while Table 3 reports the analogous information
obtained with f=0.45. The last four entries of each Table are long
duration merger candidates, which are treated apart in the analysis.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 92 216 Variability-Luminosity of 216 GRBs (f=0.8)
table3.dat 92 188 Variability-Luminosity of 188 GRBs (f=0.45)
refs.dat 99 31 References
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Byte-by-byte Description of file: table1.dat table3.dat
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Bytes Format Units Label Explanations
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1- 7 A7 --- GRB GRB name
10- 16 F7.5 --- z Redshift
18- 24 F7.2 s Tf Duraton of the time interval collecting
a fraction f of total net counts
27- 32 F6.2 s e_Tf Error of Tf (1-sigma) (1)
35- 39 F5.3 --- Vf Variability assuming f (1)
41- 45 F5.3 --- s_Vf Error of Vf (1-sigma)
47- 52 F6.3 --- Vf05 [] Negative error corresponding to 5
percentile of Vf confidence interval
54- 58 F5.3 --- Vf95 Positive error corresponding to 95
percentile of Vf confidence interval
62- 67 F6.3 [10-7W] logLiso logarithm of Liso expressed in erg/s
(isotropic-equivalent peak luminosity)
70- 74 F5.3 [10-7W] e_logLiso Error on logLiso (1-sigma)
78- 80 A3 --- Det Detector used to calculate Vf
86- 87 I2 --- r_logLiso Reference for logLiso, in refs.dat file
90- 92 I3 --- Npeaks Number of peaks (3)
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Note (1): f=0.8 for table1 and f=0.45 for table3.
Note (3): Number of peaks with S/N>5 taken from Guidorzi et al.
(2024A&A...685A..34G 2024A&A...685A..34G) and Maccary et al. (2024A&A...688L...8M 2024A&A...688L...8M).
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Byte-by-byte Description of file: refs.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Ref Reference code
4- 22 A19 --- BibCode BibCode
24- 40 A17 --- Aut Author's name
42- 99 A58 --- Com Comments
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Acknowledgements:
Cristiano Guidorzi, guidorzi(at)fe.infn.it
(End) Patricia Vannier [CDS] 27-Sep-2024