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Overall Evolution of Jetted Gamma-ray Burst Ejecta
Astrophysics · Submitted 27 Oct 1999
abstract compiled · 2026-09-23 · no language-model review
The authors' main claim However, an obvious break does appear at the transition from the relativistic phase to the Newtonian phase if the physical parameters involved are properly assumed.
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The paper's own sentences, arranged. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.
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The abstract, sentence by sentence
Whether gamma-ray bursts are highly beamed or not is a very difficult but important problem that we are confronted with. Some theorists suggest that beaming effect usually leads to a sharp break in the afterglow light curve during the ultra-relativistic phase, with the breaking point determined by $\gamma = 1 / \theta_0$, where $\gamma$ is the Lorentz factor of the blastwave and $\theta_0$ is the initial half opening angle of the ejecta, but numerical studies tend to reject the suggestion. We note that previous studies are uniformly based on dynamics that is not proper for non-relativistic blastwaves. Here we investigate the problem in more detail, paying special attention to the transition from the ultra-relativistic phase to the non-relativistic phase. Due to some crucial refinements in the dynamics, we can follow the overall evolution of a realistic jet till its velocity is as small as $\beta c \sim 10^{-3} c$. We find no obvious break in the optical light curve during the relativistic phase itself. However, an obvious break does appear at the transition from the relativistic phase to the Newtonian phase if the physical parameters involved are properly assumed. Generally speaking, the Newtonian phase is characterized by a sharp decay of optical afterglows, with the power law timing index $\alpha \sim 1.8$ - 2.1. This is due to the quick lateral expansion at this stage. The quick decay of optical afterglows from GRB 970228, 980326, and 980519, and the breaks in the optical light curves of GRB 990123 and 990510 may indicate the presence of highly collimated $\gamma$-ray burst ejecta.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | Whether gamma-ray bursts are highly beamed or not is a very difficult but important problem that we are confronted with. | background 0.99 | 0.05 | 0.02 | asserted 0.89 |
| s1 | Some theorists suggest that beaming effect usually leads to a sharp break in the afterglow light curve during the ultra-relativistic phase, with the breaking point determined by $\gamma = 1 / \theta_0$, where $\gamma$ is the Lorentz factor of the blastwave and $\theta_0$ is the initial half opening angle of the ejecta, but numerical studies tend to reject the suggestion. | background 0.97 | 0.03 | 0.03 | hedged possibility 0.98 |
| s2 | We note that previous studies are uniformly based on dynamics that is not proper for non-relativistic blastwaves. | gap 0.97 | 0.10 | 0.02 | asserted 1.00 |
| s3 | Here we investigate the problem in more detail, paying special attention to the transition from the ultra-relativistic phase to the non-relativistic phase. | contribution 0.98 | 0.75 | 0.03 | asserted 0.70 |
| s4 | Due to some crucial refinements in the dynamics, we can follow the overall evolution of a realistic jet till its velocity is as small as $\beta c \sim 10^{-3} c$. | method 0.67 | 0.93 | 0.05 | asserted 1.00 |
| s5 | We find no obvious break in the optical light curve during the relativistic phase itself. | result 1.00 | 0.96 | 0.16 | asserted 1.00 |
| s6 | However, an obvious break does appear at the transition from the relativistic phase to the Newtonian phase if the physical parameters involved are properly assumed. | result 1.00 | 0.92 | 0.63 | asserted 0.93 |
| s7 | Generally speaking, the Newtonian phase is characterized by a sharp decay of optical afterglows, with the power law timing index $\alpha \sim 1.8$ - 2.1. | result 0.79 | 0.68 | 0.13 | asserted 0.98 |
| s8 | This is due to the quick lateral expansion at this stage. | interpretation 0.96 | 0.52 | 0.04 | asserted 1.00 |
| s9 | The quick decay of optical afterglows from GRB 970228, 980326, and 980519, and the breaks in the optical light curves of GRB 990123 and 990510 may indicate the presence of highly collimated $\gamma$-ray burst ejecta. | interpretation 0.96 | 0.19 | 0.24 | hedged possibility 1.00 |
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The paper
Original abstract
Whether gamma-ray bursts are highly beamed or not is a very difficult but important problem that we are confronted with. Some theorists suggest that beaming effect usually leads to a sharp break in the afterglow light curve during the ultra-relativistic phase, with the breaking point determined by $\gamma = 1 / \theta_0$, where $\gamma$ is the Lorentz factor of the blastwave and $\theta_0$ is the initial half opening angle of the ejecta, but numerical studies tend to reject the suggestion. We note that previous studies are uniformly based on dynamics that is not proper for non-relativistic blastwaves. Here we investigate the problem in more detail, paying special attention to the transition from the ultra-relativistic phase to the non-relativistic phase. Due to some crucial refinements in the dynamics, we can follow the overall evolution of a realistic jet till its velocity is as small as $\beta c \sim 10^{-3} c$. We find no obvious break in the optical light curve during the relativistic phase itself. However, an obvious break does appear at the transition from the relativistic phase to the Newtonian phase if the physical parameters involved are properly assumed. Generally speaking, the Newtonian phase is characterized by a sharp decay of optical afterglows, with the power law timing index $\alpha \sim 1.8$ - 2.1. This is due to the quick lateral expansion at this stage. The quick decay of optical afterglows from GRB 970228, 980326, and 980519, and the breaks in the optical light curves of GRB 990123 and 990510 may indicate the presence of highly collimated $\gamma$-ray burst ejecta.
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2 arXiv papers cite this in 4 sentences
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Uses its method or tool 1 paper
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To calculate the dynamics of the evolution of the blast wave including the transition from the quasi-free expansion, through the deceleration and into the self-similar phase, we use the relativistic hydrodynamics equations for the evolution of the shock radius $R$, the mass $m$ swept up by the shock, the opening half-angle of jet $θ$ and the Lorentz factor of the shock $Γ$ [ref] (see Appendix A), and solve these equations numerically.
On the High Energy Emission of the Short GRB 090510 · Forward Shock Synchrotron Emission Evolution · 0.99
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