J/ApJ/800/16 Swift-XRT long GRB durations (Boer+, 2015)
Are ultra-long gamma-ray bursts different?
Boer M., Gendre B., Stratta G.
<Astrophys. J., 800, 16 (2015)>
=2015ApJ...800...16B 2015ApJ...800...16B
ADC_Keywords: Gamma rays
Keywords: gamma-ray burst: general
Abstract:
The discovery of a number of gamma-ray bursts (GRBs) with duration
exceeding 1000s has opened the debate on whether these bursts form a
new class of sources, the so-called ultra-long GRBs, or if they are
rather the tail of the distribution of the standard long GRB duration.
Using the long GRB sample detected by Swift, we investigate the
statistical properties of long GRBs and compare them with the
ultra-long burst properties. We compute the burst duration of long
GRBs using the start epoch of the so-called "steep decay" phase
detected with Swift/XRT. We discuss also the differences observed in
their spectral properties. We find that ultra-long GRBs are
statistically different from the standard long GRBs with typical burst
duration less than 100-500s, for which a Wolf-Rayet star progenitor is
usually invoked. Together with the presence of a thermal emission
component we interpret this result as indication that the usual long
GRB progenitor scenario cannot explain the extreme duration of
ultra-long GRBs, their energetics, as well as the mass reservoir and
size that can feed the central engine for such a long time.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 16 207 Our long GRB sample and the associated duration of
the burst event in X-rays until the steep decay,
taken from the XRT GRB catalog best fit parameters
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See also:
J/ApJ/711/495 : Durations of Swift/BAT GRBs (Butler+, 2010)
J/ApJ/701/824 : Afterglows of short & long-duration GRBs (Nysewander+, 2009)
J/MNRAS/397/1177 : Swift-XRT observations of GRBs (Evans+, 2009)
J/AJ/133/1027 : Positions for 179 Swift X-ray afterglows (Butler+, 2007)
J/A+A/448/L9 : Position catalogue of Swift XRT afterglows (Moretti+, 2006)
http://www.swift.ac.uk/xrt_live_cat : The Swift-XRT GRB online catalogue
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)
9- 16 F8.2 s TX [48/25400] Duration (TX)
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 25-Jun-2015