1,686 research outputs found
Two and a half years of GRB localizations with the INTEGRAL Burst Alert System
We review the results on Gamma-ray Bursts obtained during the first two and a
half years of operations of the INTEGRAL Burst Alert System (IBAS). In many
cases GRB coordinates have been distributed with an unprecedented combination
of accuracy (3 arcmin) and speed (20-30 s). The resulting rapid follow-ups at
other wavelengths, including sensitive XMM-Newton and Swift observations, have
led to several interesting results.Comment: A shorter version of this paper will be published in the Proceedings
of the 4th Workshop "Gamma-Ray Bursts in the Afterglow Era", Roma, 2004
October 18-22, eds. L. Piro, L. Amati, S. Covino, and B. Gendre. Il Nuovo
Cimento, in pres
The Integral Burst Alert System (IBAS)
We describe the INTEGRAL Burst Alert System (IBAS): the automatic software
for the rapid distribution of the coordinates of the Gamma-Ray Bursts detected
by INTEGRAL. IBAS is implemented as a ground based system, working on the
near-real time telemetry stream. During the first six months of operations, six
GRB have been detected in the field of view of the INTEGRAL instruments and
localized by IBAS. Positions with an accuracy of a few arcminutes are currently
distributed by IBAS to the community for follow-up observations within a few
tens of seconds of the event.Comment: 7 pages, latex, 5 figures, Accepted for publication on A&A Special
Issue on First Science with INTEGRA
The spectral catalogue of INTEGRAL gamma-ray bursts: results of the joint IBIS/SPI spectral analysis
We present the updated INTEGRAL catalogue of gamma-ray bursts (GRBs) observed
between December 2002 and February 2012. The catalogue contains the spectral
parameters for 59 GRBs localized by the INTEGRAL Burst Alert System (IBAS). We
used the data from the two main instruments on board the INTEGRAL satellite:
the spectrometer SPI (SPectrometer on INTEGRAL) nominally covering the energy
range 18 keV - 8 MeV, and the imager IBIS (the Imager on Board the INTEGRAL
Satellite) operating in the range from 15 keV to 10 MeV. For the spectral
analysis we applied a new data extraction technique, developed in order to
explore the energy regions of highest sensitivity for both instruments, SPI and
IBIS. It allowed us to perform analysis of the GRB spectra over a broad energy
range and to determine the bursts' spectral peak energies. The spectral
analysis was performed on the whole sample of GRBs triggered by IBAS, including
all the events observed in period December 2002 - February 2012. The catalogue
contains the trigger times, burst coordinates, positional errors, durations and
peak fluxes for 28 unpublished GRBs observed between September 2008 and
February 2012. The light curves in 20 - 200 keV energy band of these events
were derived using IBIS data. We compare the prompt emission properties of the
INTEGRAL GRB sample with the BATSE and Fermi samples.Comment: 16 pages, 40 figures, accepted for publication in Astronomy &
Astrophysic
Real time localization of Gamma Ray Bursts with INTEGRAL
The INTEGRAL satellite has been successfully launched in October 2002 and has
recently started its operational phase. The INTEGRAL Burst Alert System (IBAS)
will distribute in real time the coordinates of the GRBs detected with
INTEGRAL. After a brief introduction on the INTEGRAL instruments, we describe
the main IBAS characteristics and report on the initial results. During the
initial performance and verification phase of the INTEGRAL mission, which
lasted about two months, two GRBs have been localized with accuracy of about
2-4 arcmin. These observations have allowed us to validate the IBAS software,
which is now expected to provide quick (few seconds delay) and precise (few
arcmin) localization for about 10-15 GRBs per year.Comment: 6 pages, latex, 3 figures, submitted to Adv. Sp. Res., Proceedings of
the 34th COSPAR Scientific Assembly, Houston, 10-19 October 200
GRB 140206A: the most distant polarized Gamma-Ray Burst
The nature of the prompt gamma-ray emission of Gamma-Ray Bursts (GRBs) is
still far from being completely elucidated. The measure of linear polarization
is a powerful tool that can be used to put further constraints on the content
and magnetization of the GRB relativistic outflows, as well as on the radiation
processes at work.
To date only a handful of polarization measurements are available for the
prompt emission of GRBs. Here we present the analysis of the prompt emission of
GRB 140206A, obtained with INTEGRAL/IBIS, Swift/BAT, and Fermi/GBM. Using
INTEGRAL/IBIS as a Compton polarimeter we were able to constrain the linear
polarization level of the second peak of this GRB as being larger than 28% at
90% c.l.
We also present the GRB afterglow optical spectroscopy obtained at the
Telescopio Nazionale Galileo (TNG), which allowed us the measure the distance
of this GRB, z=2.739. This distance value together with the polarization
measure obtained with IBIS, allowed us to derive the deepest and most reliable
limit to date (xi <1x10-16) on the possibility of Lorentz Invariance Violation,
measured through the vacuum birefringence effect on a cosmological source.Comment: 9 pages, 5 figures, 3 tables, accepted for publication in MNRAS.
arXiv admin note: text overlap with arXiv:1303.418
The first giant flare from SGR 1806-20: observations with the INTEGRAL SPI Anti-Coincidence Shield
A giant flare from the Soft Gamma-ray Repeater SGR 1806-20 has been detected
by several satellites on 2004 December 27. This tremendous outburst, the first
one observed from this source, was a hundred times more powerful than the two
previous giant flares from SGR 0525-66 and SGR 1900+14. We report the results
obtained for this event with the Anticoincidence Shield of the SPI spectrometer
on board the INTEGRAL satellite, which provides a high-statistics light curve
at E>~80 keV. The flare started with a very strong pulse, which saturated the
detector for ~0.7 s, and whose backscattered radiation from the Moon was
detected 2.8 s later. This was followed by a ~400 s long tail modulated at the
neutron star rotation period of 7.56 s. The tail fluence corresponds to an
energy in photons above 3 keV of 1.6x10^44 (d/15 kpc)^2 erg. This is of the
same order of the energy emitted in the pulsating tails of the two giant flares
seen from other soft repeaters, despite the hundredfold larger overall emitted
energy of the SGR 1806-20 giant flare. Long lasting (~1 hour) hard X-ray
emission, decaying in time as t^-0.85, and likely associated to the SGR 1806-20
giant flare afterglow has also been detected.Comment: revised version - Accepted for publication on The Astrophysical
Journal Letter
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