• Spectral analysis of time-inte...

Result: Spectral analysis of time-integrated Konus―Wind GRBs: Implication on radiative mechanisms

Title:
Spectral analysis of time-integrated Konus―Wind GRBs: Implication on radiative mechanisms
Authors:
FOUKA, M, OUICHAOUI, S
Source:
NEUTRON STARS AND GAMMA RAY BURSTSAdvances in space research. 47(8):1387-1403
Publisher Information:
Oxford: Elsevier, 2011.
Publication Year:
2011
Physical Description:
print, 1 p
Original Material:
INIST-CNRS
Subject Terms:
Astronomy earth cosmic environment, Astronomie et environnement cosmique terrestre, Sciences exactes et technologie, Exact sciences and technology, Terre, ocean, espace, Earth, ocean, space, Astronomie, Astronomy, Astronomie fondamentale et astrophysique. Instrumentation, techniques, et observations astronomiques, Fundamental astronomy and astrophysics. Instrumentation, techniques, and astronomical observations, Instruments d'astronomie et de recherche spatiale, Astronomical and space-research instrumentation, Télescopes rx et rγ, et instrumentation, X-ray and γ-ray telescopes and instrumentation, Systèmes stellaires. Objets et systèmes galactiques et extragalactiques. L'univers, Stellar systems. Galactic and extragalactic objects and systems. The universe, Sources non identifiées de rayonnement à l'extérieur du système solaire, Unidentified sources and radiation outside the solar system, Sources rγ ; sursauts rγ, Gamma-ray sources ; gamma-ray bursts, Analyse spectrale, Spectral analysis, Boule feu, Fireballs, Corps noir, Blackbody, Cuerpo negro, Distribution électron, Electron distribution, Distribución electrón, Emission gamma, Gamma emission, Emisión gamma, Loi puissance, Power law, Ley poder, Modèle 2 composantes, Two component model, Modelo 2 componentes, Mécanisme rayonnement, Radiation mechanism, Mecanismo radiación, Polarisation rayonnement gamma, Gamma-ray polarization, Rayonnement gamma, Gamma radiation, Rayonnement non thermique, Nonthermal radiation, Rayonnement thermique, Thermal radiation, Satellite Wind, Wind satellite, Satélite Wind, Source gamma cosmique, Cosmic gamma sources, Spectre émission, Emission spectra, Sursaut Rγ, Gamma ray burst, Arrebato Rγ, Gamma-rays: bursts, Gamma-rays: theory, Radiation mechanisms: non-thermal, Radiation mechanisms: thermal
Document Type:
Academic journal Article
File Description:
text
Language:
English
Author Affiliations:
Research Center in Astronomy, Astrophysics and Geophysics, B.P. 63, Algiers Observatory, Bouzareah, Algiers, Algeria
University of Sciences and Technology, H. Boumediene, Faculty of Physics, B.P. 32, 16111 Bab Ezzouaz, Algiers, Algeria
ISSN:
0273-1177
Access URL:
http://pascal-francis.inist.fr/vibad/index.php?action=search&terms=24107326
Rights:
Copyright 2015 INIST-CNRS
CC BY 4.0
Sauf mention contraire ci-dessus, le contenu de cette notice bibliographique peut être utilisé dans le cadre d’une licence CC BY 4.0 Inist-CNRS / Unless otherwise stated above, the content of this bibliographic record may be used under a CC BY 4.0 licence by Inist-CNRS / A menos que se haya señalado antes, el contenido de este registro bibliográfico puede ser utilizado al amparo de una licencia CC BY 4.0 Inist-CNRS
Notes:
Astronomy
Accession Number:
edscal.24107326
Database:
PASCAL Archive

Further Information

We have analysed a sample of 328 time-integrated GRB prompt emission spectra taken via the Konus instrument on board the US GGS-Wind spacecraft between 2002 and 2004 using a couple of two-components models, Cut-off Power Law (CPL) + Power Law (PL) and blackbody (BB) + PL. The spectra show clear deviation from the Band function. The PL term is interpreted as the low energy tail of a nonthermal emission mechanism. The distributions of corresponding index β give values β < ―2/3 consistent with synchrotron and synchrotron self-Compton mechanisms. The distribution of low energy index α associated with the CPL term shows clear discordance with synchrotron models for 31.4% of the analysed GRBs with values exceeding that for the line of death, α = ―2/3. Then, a set of non-thermal radiation mechanisms producing harder slopes, i.e., α > ―2/3, are presented and discussed. For the remaining majority (68.6%) of GRBs with CPL index α < ―2/3, we show that optically thin synchrotron produced by a power law electron distribution of type, N(γ) ∼ γ―p, γ1 < γ < γ2, for finite energy range (γ2 ≠ oc) is a likely emission mechanism with α ∼―(p + 1)/2 in the frequency range v1 « v « v2 (where v2 = η2v1 with η = γ2/γ1), such that for p > 1/3, one gets α < ―2/3. We also show that corresponding spectra in terms of Fv and vFv functions are peaked around frequency v2 instead of v1, respectively for p < 1 and p < 3. Besides, thermal emission is examined taking a single Planck function for fitting the low energy range. It can be interpreted as an early emission from the GRB fireball photosphere with observed mean temperature, kT ∼ 16.8 keV. Furthermore, we have performed a statistical comparison between the CPL + PL and BB + PL models finding comparable χ2-values for an important fraction of GRBs, which makes it difficult to distinguish which model and specific radiation mechanism (possible thermal or nonthermal γ-ray emissions) are best suitable for describing the reported data. Therefore, additional information for those bursts, such as γ-ray polarization, would be highly desirable in future determinations of GRBs observational data.