1,307 research outputs found
Calibrating SPI-ACS/INTEGRAL for gamma-ray bursts and re-estimating energetics of GRB/GW 190425 in gamma-ray range
SPI-ACS/INTEGRAL is one of the most sensitive orbital gamma-ray detectors in
energy range above 80 keV. Since 2002 it registered several thousands of
gamma-ray bursts, including the bursts associated with LIGO-Virgo gravitational
wave events GW 170817 and GW 190425. No dedicated in-flight calibrations were
performed for SPI-ACS/INTEGRAL, complicating estimation of spectral and
energetic characteristics of an event. Using data of GBM/Fermi we perform
cross-calibration of SPI-ACS/INTEGRAL, based on 1032 bright GRBs registered by
both experiments. We find the conversion factor between instrumental counts
from SPI-ACS and energy units from GBM to be dependent on hardness of GRB
spectrum (defined as the characteristic energy value, ) and on location
of a source in spacecraft based coordinate system. We determine the
corresponding analytical model to calculate the conversion factor and estimate
its accuracy empirically. Sensitivity of SPI-ACS/INTEGRAL to detect gamma-ray
transients is also investigated. Using the calibration we re-estimate
energetics of GRB/GW 190425, detected by SPI-ACS/INTEGRAL alone. We constrain
possible range of the characteristic energy and isotropic equivalent of
total energy, emitted in gamma-rays for GRB 190425, using the -- (Amati) correlation. The calibration model could be
applied to any transients with energy spectrum, analogous to gamma-ray bursts.Comment: 11 pages, 11 figures, Accepted to MNRAS 2023 August 3, in original
form 2023 June 2
Investigation of the spectral lag - energy relation of GRBs registered by INTEGRAL
We investigated the dependence of spectral lag on energy band based on 28
bright GRBs detected by the SPI and IBIS/ISGRI instruments on the INTEGRAL
observatory. It is found that for simple structured bursts or well separated
pulses of multi-pulse bursts the spectral lag can be approximated by the
relation t=Alog(E), where A is a positive parameter, which correlates with
pulse duration. We have not found any negative lag in simple structured bursts
or in well separated pulses. While investigating the time profile of the whole
burst negative lag may appear due to different spectral parameters of the
pulses.Comment: 6 pages, 2 figures, Proceedings of "An INTEGRAL view of the
high-energy sky (the first 10 years)" the 9th INTEGRAL Workshop, October
15-19, 2012, Paris, France, in Proceedings of Science (INTEGRAL 2012), Eds.
A. Goldwurm, F. Lebrun and C. Winkler,
(http://pos.sissa.it/cgi-bin/reader/conf.cgi?confid=176), id 12
Extended Emission of Cosmic Gamma-Ray Bursts Detected in the SPI-ACS/INTEGRAL Experiment
We have carried out a systematic analysis of the gamma-ray bursts' (GRBs)
light curves detected in the SPI-ACS experiment onboard the INTEGRAL
observatory aimed to search extended emission. The emission occasionally
recorded after the prompt active phase of a GRB in the form of an emission that
is longer than the active phase and less intense is called the extended one.
Out of the 739 brightest GRBs recorded from 2002 to 2017, extended emission has
been detected in of the individual light curves; its maximum
duration reaches s. Two different types of extended emission have
been revealed. One of them is an additional component of the light curve and is
described by a power law (PL) with an index close to the PL
index of the afterglow in the optical and X-ray bands. The second type can be
described by a steeper PL decay of the light curve typical of the active burst
phase. Extended emission has also been found in the combined light curve of
long GRBs in the individual curves of which no extended emission has been
detected. The PL index of the extended emission in the combined light curve is
. It is most likely associated with the superposition of
light curves at the active phase; its total duration is s
Flame front propagation IV: Random Noise and Pole-Dynamics in Unstable Front Propagation II
The current paper is a corrected version of our previous paper
arXiv:adap-org/9608001. Similarly to previous version we investigate the
problem of flame propagation. This problem is studied as an example of unstable
fronts that wrinkle on many scales. The analytic tool of pole expansion in the
complex plane is employed to address the interaction of the unstable growth
process with random initial conditions and perturbations. We argue that the
effect of random noise is immense and that it can never be neglected in
sufficiently large systems. We present simulations that lead to scaling laws
for the velocity and acceleration of the front as a function of the system size
and the level of noise, and analytic arguments that explain these results in
terms of the noisy pole dynamics.This version corrects some very critical
errors made in arXiv:adap-org/9608001 and makes more detailed description of
excess number of poles in system, number of poles that appear in the system in
unit of time, life time of pole. It allows us to understand more correctly
dependence of the system parameters on noise than in arXiv:adap-org/9608001Comment: 23 pages, 4 figures,revised, version accepted for publication in
journal "Combustion, Explosion and Shock Waves". arXiv admin note:
substantial text overlap with arXiv:nlin/0302021, arXiv:adap-org/9608001,
arXiv:nlin/030201
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