GRB 140423A: A Case of Stellar Wind to Interstellar Medium Transition in the Afterglow

Li, Long; Wang, Xiang-Gao; Zheng, W.; Pozanenko, A.; Filippenko, A. V.; Qin, Songmei; Wang, Shanqin; Jiang, Lu-Yao; Li, Jing; Lin, Da-Bin; Liang, En‐Wei; Volnova, A.; Elenin, L.; Klunko, E.; Inasaridze, R.; Kusakin, A. V.; Lu, Rui-Jing

doi:10.3847/1538-4357/aba757

Cited by 14 publications

(8 citation statements)

References 74 publications

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“…The posterior probability density functions for the physical parameters, i.e., E k,iso,on , Γ 0 , θ c , θ jet /θ c , θ v /θ c , p, ǫ e , ǫ B , A * , and R tr , are presented in Figure 8, where only the fitting result of GRB 120326A is shown as an example. The optimal result from MCMC fitting is shown in Figure 7 with blue line (XRT) and red line (optical), and the obtained parameters at the 1σ confidence level are reported in Table 1, where the values of the transition radius R tr (i.e., 1.05 × 10 17 cm, 6.31 × 10 16 cm, and 3.98 × 10 17 cm for GRBs 120326A, 120404A and 100814A, respectively) are consistent with those found in other bursts (e.g., Kong et al 2010;Feng & Dai 2011a;Ramirez-Ruiz et al 2001;Li et al 2020). It can be found that both the X-ray afterglow and the optical afterglow of these bumps can be well modelled with an off-axis observed external-forward shock in a free-to-shocked wind environment.…”

Section: Case Studysupporting

confidence: 82%

Late Afterglow Bump/Plateau around the Jet Break: Signature of a free-to-shocked wind Environment in Gamma-ray Burst

Li,

Lin,

Ren

et al. 2021

Preprint

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A number of gamma-ray bursts (GRBs) exhibit the late simultaneous bumps in their optical and Xray afterglows around the jet break. Its origin is unclear. Based on the following two facts, we suggest that this feature may sound a transition of circum-burst environment from a free-wind medium to a homogeneous medium. (I) The late bump followed by a steep decay is strongly reminiscent of the afterglows of GRB 170817A, which is attributed to an off-axis observed external-forward shock (eFS) propagating in an interstellar medium. (II) Observations seem to feature a long shallow decay before the late optical bump, which is different from the afterglow of GRB 170817A. In this paper, we study the emission of an eFS propagating in a free-to-shocked wind for on/off-axis observers, where the mass density in the shocked-wind is almost constant. The late simultaneous bumps/plateaux in the optical and X-ray afterglows are really found around the jet break for high-viewing-angle observers. Moreover, there is a long plateau or shallow decay before the late bump in the theoretical light-curves, which is formed during the eFS propagating in the free-wind. For low-viewing-angle observers, the above bumps appear only in the situation that the structured jet has a low characteristic angle and the deceleration radius of the on-axis jet flow is at around or beyond the free-wind boundary. As examples, the X-ray and optical afterglows of GRBs 120326A, 120404A, and 100814A are fitted. We find that an off-axis observed eFS in a free-to-shocked wind can well explain the afterglows in these bursts.

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Section: Case Studysupporting

confidence: 82%

Late Afterglow Bump/Plateau around the Jet Break: Signature of a free-to-shocked wind Environment in Gamma-ray Burst

Li,

Lin,

Ren

et al. 2021

Preprint

Self Cite

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“…There are other possible assumptions that might not necessarily hold true for the afterglow of GRB 160131A: (1) the constant micro-physics parameters, in light of the evidence of the temporal evolution of the micro-physics parameters in the afterglow of GRB 190114C (Misra et al 2021), (2) a unique CBM, as in the case of evidence of the transition from a wind-like to ISMlike CBM in the afterglow of GRB 140423A (Li et al 2020), and (3) a uniform jet model, in light of the evidence of other…”

Section: Discussionmentioning

confidence: 99%

Radio data challenge the broadband modelling of GRB 160131A afterglow

Marongiu

Guidorzi

Stratta

et al. 2022

A&A

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Context. Gamma-ray burst (GRB) afterglows originate from the interaction between the relativistic ejecta and the surrounding medium. Consequently, their properties depend on several aspects: radiation mechanisms, relativistic shock micro-physics, circumburst environment, and the structure and geometry of the relativistic jet. While the standard afterglow model accounts for the overall spectral and temporal evolution for a number of GRBs, its validity limits emerge when the data set is particularly rich and constraining, especially in the radio band. Aims. We aimed to model the afterglow of the long GRB 160131A (redshift z = 0.972), for which we collected a rich, broadband, and accurate data set, spanning from 6 × 108 Hz to 7 × 1017 Hz in frequency, and from 330 s to 160 days post-burst in time. Methods. We modelled the spectral and temporal evolution of this GRB afterglow through two approaches: (1) the adoption of empirical functions to model an optical/X-ray data set, later assessing their compatibility with the radio domain; and (2) the inclusion of the entire multi-frequency data set simultaneously through the Python package named SAGA (Software for AfterGlow Analysis), to obtain an exhaustive and self-consistent description of the micro-physics, geometry, and dynamics of the afterglow. Results. From deep broadband analysis (from radio to X-ray frequencies) of the afterglow light curves, GRB 160131A outflow shows evidence of jetted emission. Moreover, we observe dust extinction in the optical spectra, and energy injection in the optical/X-ray data. Finally, radio spectra are characterised by several peaks that could be due to either interstellar scintillation (ISS) effects or a multi-component structure. Conclusions. The inclusion of radio data in the broadband set of GRB 160131A makes a self-consistent modelling barely attainable within the standard model of GRB afterglows.

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“…Alongside the conventional environments of free stellar wind and the interstellar medium (ISM), abrupt density transitions in the surrounding medium are often mentioned (Dai & Lu 2002). Some studies have explained the sudden rebrightenings, fluctuations, and changes in decay slopes in the afterglow LCs of GRBs using models incorporating density jumps in the medium (e.g., Dai & Wu 2003;Monfardini et al 2006;Li et al 2020a). Numerical simulations have shown the mass outflows from massive stars could create a stellar wind bubble within a certain radius surrounding the star and eventually transition to a uniform ISM (e.g., Eldridge et al 2006).…”

Section: Circumburst Environmentmentioning

confidence: 99%

Jet Structure and Burst Environment of GRB 221009A

Ren,

Wang,

Dai

2024

ApJ

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We conducted a comprehensive investigation of the brightest-of-all-time GRB 221009A, using new insights from very high-energy (VHE) observations from LHAASO and a complete multiwavelength afterglow data set. Through data fitting, we imposed constraints on the jet structure, radiation mechanisms, and burst environment of GRB 221009A. Our findings reveal a structured jet morphology characterized by a core+wing configuration. A smooth transition of energy within the jet takes place between the core and wing, but with a discontinuity in the bulk Lorentz factor. The jet structure differs from both the case of the short GRB 170817A and the results of numerical simulations for long-duration bursts. The VHE emission can be explained by the forward shock synchrotron self-Compton radiation of the core component, but requiring a distinctive transition of the burst environment from uniform to wind-like, suggesting the presence of complex pre-burst mass ejection processes. The low-energy multiwavelength afterglow is mainly governed by the synchrotron radiation from the forward and reverse shocks of the wing component. Our analysis indicates a magnetization factor of 5 for the wing component. Additionally, by comparing the forward shock parameters of the core and wing components, we find a potential correlation between the electron acceleration efficiency and both the Lorentz factor of the shock and the magnetic field equipartition factor. We discuss the significance of our findings, potential interpretations, and remaining issues.

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GRB 140423A: A Case of Stellar Wind to Interstellar Medium Transition in the Afterglow

Cited by 14 publications

References 74 publications

Late Afterglow Bump/Plateau around the Jet Break: Signature of a free-to-shocked wind Environment in Gamma-ray Burst

Late Afterglow Bump/Plateau around the Jet Break: Signature of a free-to-shocked wind Environment in Gamma-ray Burst

Radio data challenge the broadband modelling of GRB 160131A afterglow

Jet Structure and Burst Environment of GRB 221009A

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