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Early Afterglows of Gamma-Ray Bursts in a Stratified Medium with a Power-Law Density Distribution
High Energy Astrophysical Phenomena · Submitted 28 Aug 2013
abstract compiled · 2026-09-23 · no language-model review
The authors' main claim We apply our model to 19 GRBs, and find that their $k$ values are in the range of 0.4 - 1.4, with a typical value of $k\sim1$, implying that this environment is neither a homogenous interstellar medium with $k=0$ nor a typical stellar wind with $k=2$.
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The abstract, sentence by sentence
A long-duration gamma-ray burst (GRB) has been widely thought to arise from the collapse of a massive star, and it has been suggested that its ambient medium is a homogenous interstellar medium (ISM) or a stellar wind. There are two shocks when an ultra-relativistic fireball that has been ejected during the prompt gamma-ray emission phase sweeps up the circumburst medium: a reverse shock that propagates into the fireball, and a forward shock that propagates into the ambient medium. In this paper, we investigate the temporal evolution of the dynamics and emission of these two shocks in an environment with a general density distribution of $n\propto R^{-k}$ (where $R$ is the radius) by considering thick-shell and thin-shell cases. A GRB afterglow with one smooth onset peak at early times is understood to result from such external shocks. Thus, we can determine the medium density distribution by fitting the onset peak appearing in the light curve of an early optical afterglow. We apply our model to 19 GRBs, and find that their $k$ values are in the range of 0.4 - 1.4, with a typical value of $k\sim1$, implying that this environment is neither a homogenous interstellar medium with $k=0$ nor a typical stellar wind with $k=2$. This shows that the progenitors of these GRBs might have undergone a new mass-loss evolution.
background contribution method result interpretation main claim
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| s0 | A long-duration gamma-ray burst (GRB) has been widely thought to arise from the collapse of a massive star, and it has been suggested that its ambient medium is a homogenous interstellar medium (ISM) or a stellar wind. | background 1.00 | 0.03 | 0.02 | hedged possibility 0.86 |
| s1 | There are two shocks when an ultra-relativistic fireball that has been ejected during the prompt gamma-ray emission phase sweeps up the circumburst medium: a reverse shock that propagates into the fireball, and a forward shock that propagates into the ambient medium. | background 1.00 | 0.05 | 0.02 | asserted 1.00 |
| s2 | In this paper, we investigate the temporal evolution of the dynamics and emission of these two shocks in an environment with a general density distribution of $n\propto R^{-k}$ (where $R$ is the radius) by considering thick-shell and thin-shell cases. | contribution 0.88 | 0.90 | 0.04 | asserted 0.80 |
| s3 | A GRB afterglow with one smooth onset peak at early times is understood to result from such external shocks. | background 0.92 | 0.05 | 0.04 | asserted 0.90 |
| s4 | Thus, we can determine the medium density distribution by fitting the onset peak appearing in the light curve of an early optical afterglow. | method 0.54 | 0.28 | 0.09 | asserted 0.73 |
| s5 | We apply our model to 19 GRBs, and find that their $k$ values are in the range of 0.4 - 1.4, with a typical value of $k\sim1$, implying that this environment is neither a homogenous interstellar medium with $k=0$ nor a typical stellar wind with $k=2$. | result 1.00 | 0.97 | 0.76 | asserted 1.00 |
| s6 | This shows that the progenitors of these GRBs might have undergone a new mass-loss evolution. | interpretation 1.00 | 0.38 | 0.22 | speculative 0.88 |
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The paper
Original abstract
A long-duration gamma-ray burst (GRB) has been widely thought to arise from the collapse of a massive star, and it has been suggested that its ambient medium is a homogenous interstellar medium (ISM) or a stellar wind. There are two shocks when an ultra-relativistic fireball that has been ejected during the prompt gamma-ray emission phase sweeps up the circumburst medium: a reverse shock that propagates into the fireball, and a forward shock that propagates into the ambient medium. In this paper, we investigate the temporal evolution of the dynamics and emission of these two shocks in an environment with a general density distribution of $n\propto R^{-k}$ (where $R$ is the radius) by considering thick-shell and thin-shell cases. A GRB afterglow with one smooth onset peak at early times is understood to result from such external shocks. Thus, we can determine the medium density distribution by fitting the onset peak appearing in the light curve of an early optical afterglow. We apply our model to 19 GRBs, and find that their $k$ values are in the range of 0.4 - 1.4, with a typical value of $k\sim1$, implying that this environment is neither a homogenous interstellar medium with $k=0$ nor a typical stellar wind with $k=2$. This shows that the progenitors of these GRBs might have undergone a new mass-loss evolution.
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References
How the literature uses it
7 arXiv papers cite this in 21 sentences
Papers citing it · 16 sentences without a confident label
Uses its method or tool 2 papers
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For the calculation of the contribution from the RS in the early afterglow phase, it is referenced from [ref] .
The Double-Burst Nature and Early Afterglow Evolution of Long GRB 110801A · Afterglow modeling · 0.96
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We consider a stratified medium with a power-law density profile [ref] : [equation] where $r$ denotes the radial distance from the central engine and $n_0 = 1 cm^-3$.
Polarization of GRB standard X-ray afterglow and its detection prospects by eXTP · The model · 0.96
Uses its data or values 1 paper
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The distribution is obtained by applying maximum-likelihood estimation to the set of $k$ values derived from the fitting of the 19-GRB afterglow [ref] .
Polarization of GRB standard X-ray afterglow and its detection prospects by eXTP · Statistical distributions · 0.91
Compares with it 1 paper
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We compare our results with the analytical study of [ref] , who analyzed early afterglow light curves of 19 GRBs, including XRF 080330 and GRB 080710, assuming thin-shell and power-law density profiles.
Revisiting early afterglows of gamma-ray bursts with finite-thickness ejecta: Implications from XRF 080330 and GRB 080710 · Possible CBM diversity as a consequence of different progenitor evolution · 0.99
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