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Beloborodov, V. L.; Zalesskaya, M. A.; Tyukavkina, N. A.

doi:10.1023/a:1010412104160

Cited by 2 publications

(4 citation statements)

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“…Our results do not agree with the very high, ∼ 80%, radiative efficiency values, obtained in the calculations of Beloborodov (2000) and Kobayashi & Sari (2001) by assuming wind Lorentz factor distributions extending from Γ m ∼ 10 to Γ M ∼ > 10 4 . In our opinion the minimum wind Lorentz factor must be significantly higher than 10 (as otherwise the wind becomes optically thick) while the maximum Lorentz factor can not significantly exceed 10 3 (due to the acceleration process limitations).…”

Section: Discussioncontrasting

confidence: 99%

“…The case of a lognormal LF distribution can be considered as an intermediate case between the random and bimodal ones. In this case the maximal radiative efficiency expected is of the order 10-15%, much lower than the 80-90% value derived in Beloborodov (2000). This is due to the pair optical depth, which sets a lower limit of Γ m ∼ > 100 for an optically thin wind (see §3.2 below), and to the constraint imposed on the maximum LF by finite source size, Γ M < η * ∼ 10 3.5 .…”

Section: Based Onmentioning

confidence: 66%

“…It has been demonstrated in earlier work (e.g. Kobayashi et al 1997;Beloborodov 2000), that high radiative efficiency may be obtained in the internal shock model provided the variance of the wind Lorentz factors distribution is large. Kobayashi et al (1997) found ∼ 10% efficiency for uniform Lorentz factor distribution with maximum to minimum Lorentz factor ratio ≈ 10, and Beloborodov (2000) demonstrated that the efficiency may approach 100% for non-uniform distributions with wide range of Lorentz factors 3 .…”

Section: Introductionmentioning

confidence: 91%

“…Kobayashi et al 1997;Beloborodov 2000), that high radiative efficiency may be obtained in the internal shock model provided the variance of the wind Lorentz factors distribution is large. Kobayashi et al (1997) found ∼ 10% efficiency for uniform Lorentz factor distribution with maximum to minimum Lorentz factor ratio ≈ 10, and Beloborodov (2000) demonstrated that the efficiency may approach 100% for non-uniform distributions with wide range of Lorentz factors 3 . In the analysis presented here we consider several issues which have not been addressed in earlier work: The constraints imposed on the model by the observed peak emission energy distribution, the effect of optical depth due to e ± pairs produced within the fireball wind, and the upper limit imposed on the maximum wind Lorentz factor by the acceleration process.…”

Section: Introductionmentioning

confidence: 99%

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Efficiency and Spectrum of Internal Gamma‐Ray Burst Shocks

Guetta

Spada

Waxman

2001

ApJ

118

141

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We present an analysis of the Internal Shock Model of GRBs, where gamma-rays are produced by internal shocks within a relativistic wind. We show that observed GRB characteristics impose stringent constraints on wind and source parameters. We find that a significant fraction, of order 20%, of the wind kinetic energy can be converted to radiation, provided the distribution of Lorentz factors within the wind has a large variance and provided the minimum Lorentz factor is > Γ ± ≈ 10 2.5 L 2/9 52 , where L = 10 52 L 52 erg s −1 is the wind luminosity. For a high, > 10%, efficiency wind, spectral energy breaks in the 0.1 to 1 MeV range are obtained for sources with dynamical time R/c ∼ < 1 ms, suggesting a possible explanation for the observed clustering of spectral break energies in this range. The lower limit Γ ± to wind Lorenz factor and the upper limit ≈ 1(R/10 7 cm) −5/6 MeV to observed break energies are set by Thomson optical depth due to e ± pairs produced by synchrotron photons. Natural consequences of the model are absence of bursts with peak emission energy significantly exceeding 1 MeV, and existence of low luminosity bursts with low, 1 keV to 10 keV, break energies.Subject headings: gamma-rays: bursts -methods: numerical -radiation mechanisms: non-thermal Both the spectrum and temporal dependence of afterglow emission are consistent with synchrotron emission of electrons accelerated to high energy at the shock wave driven by the

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Section: Discussioncontrasting

confidence: 99%

Section: Based Onmentioning

confidence: 66%

Section: Introductionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

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Efficiency and Spectrum of Internal Gamma‐Ray Burst Shocks

Guetta

Spada

Waxman

2001

ApJ

118

141

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Power Density Spectra of Gamma‐Ray Bursts

Beloborodov

Stern

Svensson

2000

ApJ

113

120

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Power density spectra (PDSs) of long gamma-ray bursts (GRBs) provide useful information on GRBs, indicating their self-similar temporal structure. The best power-law PDSs are displayed by the longest bursts s) in which the range of self-similar timescales covers more than 2 decades. Shorter (T 90[ 100 bursts have apparent PDS slopes more strongly a †ected by statistical Ñuctuations. The underlying power law can then be reproduced with high accuracy by averaging the PDSs for a large sample of bursts. This power law has a slope a B [5/3 and a sharp break at D1 Hz. The power-law PDS provides a new sensitive tool for studies of GRBs. In particular, we calculate the PDSs of bright bursts in separate energy channels. The PDS Ñattens in the hard channel (hl [ 300 keV) and steepens in the soft channel (hl \ 50 keV), while the PDS of bolometric light curves approximately follows the [ 5/3 law. We then study dim bursts and compare them to the bright ones. We Ðnd a strong correlation between the burst brightness and the PDS slope. This correlation shows that the bursts are far from being standard candles and dim bursts should be intrinsically weak. The time dilation of dim bursts is probably related to physical processes occurring in the burst rather than to a cosmological redshift.

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Cited by 2 publications

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Efficiency and Spectrum of Internal Gamma‐Ray Burst Shocks

Efficiency and Spectrum of Internal Gamma‐Ray Burst Shocks

Power Density Spectra of Gamma‐Ray Bursts

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