Spectral evolution of gamma-ray bursts detected by the SIGNE experiment. 1: Correlation between intensity and spectral hardness

Kargatis, Vincent E.; Liang, Edison; Hurley, K.; Barat, C.; Eveno, E.; Niel, M.

doi:10.1086/173724

Cited by 64 publications

(62 citation statements)

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“…15 suggests a marginal hard-to-soft evolution of the photon index, the peak energy (Fig. 16) shows all the possible cases compatibly with no standard evolution, in agreement with early observations of GRBs from past experiments (e.g., Kargatis et al 1994;K06). The variety of the peak energy evolution throughout the time profile of a GRB is known to undergo a range of different behaviours: either tracking of the light curve or a steady hard-to-soft evolution are observed (e.g.…”

Section: Time Resolved Spectrasupporting

confidence: 85%

Spectral catalogue of bright gamma-ray bursts detected with theBeppoSAX/GRBM

Guidorzi

Lacapra

Frontera

et al. 2010

A&A

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Context. The emission process responsible for the so-called "prompt" emission of gamma-ray bursts is still unknown. A number of empirical models fitting the typical spectrum still lack a satisfactory interpretation. A few GRB spectral catalogues derived from past and present experiments are known in the literature and allow to tackle the issue of spectral properties of gamma-ray bursts on a statistical ground. Aims. We extracted and studied the time-integrated photon spectra of the 200 brightest GRBs observed with the Gamma-Ray Burst Monitor which flew aboard the BeppoSAX mission (1996)(1997)(1998)(1999)(2000)(2001)(2002) to provide an independent statistical characterisation of GRB spectra. Methods. The spectra have a time-resolution of 128 s and consist of 240 energy channels covering the 40-700 keV energy band. The 200 brightest GRBs were selected from the complete catalogue of 1082 GRBs detected with the GRBM ), whose products are publicly available and can be browsed/retrieved using a dedicated web interface. The spectra were fit with three models: a simple power law, a cut-off power law or a Band model. We derived the sample distributions of the best-fitting spectral parameters and investigated possible correlations between them. For a few, typically very long GRBs, we also provide a loose (128-s) time-resolved spectroscopic analysis. Results. The typical photon spectrum of a bright GRB consists of a low-energy index around 1.0 and a peak energy of the ν F ν spectrum E p 240 keV in agreement with previous results on a sample of bright CGRO/BATSE bursts. Spectra of ∼35% of GRBs can be fit with a power law with a photon index around 2, indicative of peak energies either close to or outside the GRBM energy boundaries. We confirm the correlation between E p and fluence, in agreement with previous results, with a logarithmic dispersion of 0.13 around the power law with index 0.21 ± 0.06. This is shallower than its analogous in the GRB rest-frame, the Amati relation, between the intrinsic peak energy and the isotropic-equivalent released energy (slope of ∼0.5). The reason for this difference mainly lies in the instrumental selection effect connected with the finite energy range of the GRBM particularly at low energies. Conclusions. We confirm the statistical properties of the low-energy index and peak energy distributions found by other experiments. These properties are not yet systematically explained in the current literature with the proposed emission processes. The capability of measuring time-resolved spectra over a broadband energy range, ensuring precise measurements of parameters such as E p , will be of key importance for future experiments.

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Section: Time Resolved Spectrasupporting

confidence: 85%

Spectral catalogue of bright gamma-ray bursts detected with theBeppoSAX/GRBM

Guidorzi

Lacapra

Frontera

et al. 2010

A&A

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“…Studies show that a E p evolutionary curve of drop-to-rise-to-decay evolution (i.e., A, B, and C phase) could always be found, despite different ratios of the rising portion to the decaying portion of its corresponding local pulse, and with the increase of the ratio, both the A and B phase of the corresponding evolutionary curve of E p would become longer. But the peak in E p of the B phase would always lead the corresponding light-curve peak for any local pulse with a rising portion, which may be the cause of the observed fact that the spectral hardness of some GRBs peaks on the leading edges of the GRB pulses (e.g., Norris et al 1986;Kargatis et al 1994;Ford et al 1995).…”

Section: The Case Of a Constant Rest-frame Spectrummentioning

confidence: 99%

“…The evolution has been studied over both the entire burst, giving the overall behavior, and the individual pulse structures, enabling us to better understand the physical mechanisms of the GRB prompt emission process. Such hardness parameters were typically found either to follow a ''hard-tosoft'' trend (Norris et al 1986), decreasing monotonically while the flux rises and falls, or to ''track'' the flux during an individual pulse, with the spectral hardness peaking on the leading edges of pulses ( Wheaton et al 1973;Norris et al 1986;Golenetskii et al 1983;Laros et al 1985;Kargatis et al 1994;Ford et al 1995).…”

Section: Introductionmentioning

confidence: 99%

Spectral Hardness Evolution of Gamma‐Ray Bursts Due to the Doppler Effect of Fireballs

Peng

Dong

2007

ApJ

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We have investigated the evolution of observed spectral hardness E p (where E p is the maximum of the F spectrum) based on the model of highly symmetric expanding fireballs, where the Doppler effect of the expanding fireball surface is the key factor concerned, and find that the evolutionary curve of E p undergoes a drop to rise to decay evolution (the A, B, and C phases, respectively). The A phase peaks at the very onset of the corresponding light-curve pulse. Since the Doppler effect is less prominent in the B phase, corresponding to the rising portion of the pulse, the slope of the B phase reflects both the corresponding intrinsic spectral evolution and the shape of its local pulse. The C phase, corresponding to the decay portion of the pulse, where the Doppler effect dominates, always decreases monotonically and does not necessarily reflect the corresponding intrinsic spectral evolution. Investigation of a sample of 12 FRED pulses (their peak energy can be found in the work of Kaneko et al.) shows that the evolutionary characteristics of the fitted peak energy in the FRED pulses are in good agreement with our predictions.

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“…A more robust correlation that is certainly not affected by selection effects is the Golenetskii correlation, discovered by the Konus experiment (Golenetskii et al 1983) and confirmed more recently with the high-quality Fermi spectral data (Ghirlanda et al 2010;Lu et al 2012). According to the Golenetskii correlation, different time intervals of a single burst aligned along a straight line when plotted in the luminosity-peak frequency plane (for further discussion see Bhat et al (1994); Borgonovo & Ryde (2001);Ford et al (1995); Kargatis et al (1994); Lu et al (2010); Norris et al (1986); Peng et al (2009). The burst spectrum peaks at lower frequencies when the emission is weak but moves to higher frequencies when it is bright.…”

Section: Introductionmentioning

confidence: 69%

Photospheric emission from long duration gamma-ray bursts powered by variable engines

López-Cámara

Morsony

Lazzati

2015

Proceedings of Swift: 10 Years of Discovery — PoS(SWIFT 10)

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We present the results of a set of numerical simulations of long-duration gamma-ray burst jets aimed at studying the effect of a variable engine on the peak frequency of the photospheric emission. Our simulations follow the propagation of the jet inside the progenitor star, its break-out, and the subsequent expansion in the environment out to the photospheric radius. A constant and two step-function models are considered for the engine luminosity. We show that our synthetic light-curves follow a luminosity-peak frequency correlation analogous to the Golenetskii correlation found in long-duration gamma-ray burst observations. Within the parameter space explored, it appears that the central engine luminosity profile does not have a significant effect on the location of a gamma-ray burst in the Luminosity-peak frequency plane, bursts from different central engines being indistinguishable from each other.

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Spectral evolution of gamma-ray bursts detected by the SIGNE experiment. 1: Correlation between intensity and spectral hardness

Cited by 64 publications

References 0 publications

Spectral catalogue of bright gamma-ray bursts detected with theBeppoSAX/GRBM

Spectral catalogue of bright gamma-ray bursts detected with theBeppoSAX/GRBM

Spectral Hardness Evolution of Gamma‐Ray Bursts Due to the Doppler Effect of Fireballs

Photospheric emission from long duration gamma-ray bursts powered by variable engines

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