Issue |
A&A
Volume 496, Number 3, March IV 2009
|
|
---|---|---|
Page(s) | 585 - 595 | |
Section | Astrophysical processes | |
DOI | https://doi.org/10.1051/0004-6361/200811209 | |
Published online | 09 February 2009 |
Short versus long gamma-ray bursts: spectra, energetics, and luminosities
1
Osservatorio Astronomico di Brera, via E. Bianchi 46, 23807 Merate (LC), Italy e-mail: giancarlo.ghirlanda@brera.inaf.it
2
Università degli Studi dell'Insubria, Dipartimento di Fisica e Matematica, via Valleggio 11, 22100 Como, Italy
3
SISSA, via Beirut 2/4, 34014, Trieste, Italy
4
Instituto de Astronomia, Universidad Nacional Autonoma de Mexico, A.P. 70-264, 04510 Mexico D.F., Mexico
Received:
22
October
2008
Accepted:
6
January
2009
We compare the spectral properties of 79 short and 79 long
Gamma-Ray Bursts (GRBs) detected by BATSE and selected with the same
limiting peak flux. Short GRBs have a low-energy spectral component harder
and a peak energy slightly higher than long GRBs, but no difference is found
when comparing short GRB spectra with those of the first 1-2 s emission
of long GRBs. These results confirm earlier findings for brighter GRBs. The
bolometric peak flux of short GRBs correlates with their peak energy in a
similar way to long bursts. Short and long GRBs populate different
regions of the bolometric fluence-peak energy plane, short bursts being
less energetic by a factor similar to the ratio of their durations. If
short and long GRBs had similar redshift distributions, they would have
similar luminosities yet different energies, which correlate with the peak
energy Epeak for the population of long GRBs. We also test whether short
GRBs are consistent with the and
correlations for the available
sample of short (6 events) and long (92 events) GRBs with measured redshifts
and
: while short GRBs are inconsistent with the
correlation of
long GRBs, they could follow the
correlation of long bursts. All the
above indications point to short GRBs being similar to the first phases of
long bursts. This suggests that a similar central engine (except for its
duration) operates in GRBs of different durations.
Key words: gamma ray: bursts / stars: neutron / radiation mechanisms: thermal
© ESO, 2009
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