“Double-tracking” Characteristics of the Spectral Evolution of GRB 131231A: Synchrotron Origin?

Li, Liang; Geng, Jin-Jun; Meng, Yan-Zhi; Wu, Xue-Feng; Huang, Yun‐Feng; Wang, Yu; Moradi, R.; Uhm, Z. Lucas; Zhang, Bing

doi:10.3847/1538-4357/ab40b9

Cited by 39 publications

(43 citation statements)

References 99 publications

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“…So far, this tracking behaviour has only been found in a few GRBs, i.e. in GRB 131231A (Li et al 2019) and GRB 140102A (Gupta et al 2021b), the low energy spectral index remains in the synchrotron limit (𝛼 𝑝𝑡 = −2/3). Similarly, in the case of GRB 190530A, 𝛼 pt values are within the synchrotron limits for the first two pulses.…”

Section: Discussionmentioning

confidence: 92%

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Probing into emission mechanisms of GRB 190530A using time-resolved spectra and polarization studies: Synchrotron Origin?

Gupta,

Chattopadhyay

et al. 2022

Preprint

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Multi-pulsed GRB 190530A, detected by the GBM and LAT onboard Fermi, is the sixth most fluent GBM burst detected so far. This paper presents the timing, spectral, and polarimetric analysis of the prompt emission observed using AstroSat and Fermi to provide insight into the prompt emission radiation mechanisms. The time-integrated spectrum shows conclusive proof of two breaks due to peak energy and a second lower energy break. Time-integrated (55.43 ± 21.30 %) as well as time-resolved polarization measurements, made by the Cadmium Zinc Telluride Imager (CZTI) onboard AstroSat, show a hint of high degree of polarization. The presence of a hint of high degree of polarization and the values of low energy spectral index (𝛼 pt ) do not run over the synchrotron limit for the first two pulses, supporting the synchrotron origin in an ordered magnetic field. However, during the third pulse, 𝛼 pt exceeds the synchrotron line of death in few bins, and a thermal signature along with the synchrotron component in the time-resolved spectra is observed. Furthermore, we also report the earliest optical observations constraining afterglow polarization using the MASTER (P < 1.3 %) and the redshift measurement (𝑧= 0.9386) obtained with the 10.4m GTC telescopes. The broadband afterglow can be described with a forward shock model for an ISM-like medium with a wide jet opening angle. We determine a circumburst density of 𝑛 0 ∼ 7.41, kinetic energy 𝐸 K ∼ 7.24 ×10 54 erg, and radiated 𝛾-ray energy 𝐸 𝛾,iso ∼ 6.05 ×10 54 erg, respectively.

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Section: Discussionmentioning

confidence: 92%

“…The 𝛼 pt also evolves with time but does not display any typical trends (Crider et al 1997). Recently, Li et al (2019) and Gupta et al (2021b) found that both 𝐸 p and 𝛼 pt track flux ("double-tracking") for GRB 131231A and GRB 140102A.…”

Section: Introductionmentioning

confidence: 99%

Probing into emission mechanisms of GRB 190530A using time-resolved spectra and polarization studies: Synchrotron Origin?

Gupta,

Chattopadhyay

et al. 2022

Preprint

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“…To test the applicability of our calculations, we perform theoretical modeling of two representative short GRBs, i.e., GRB 110529A (intensity-tracking) and GRB 090227B (hard-to-soft) respectively. The data used from Fermi-GBM 2 is analyzed with the standard Bayesian approach and the time bin selection method to obtain the time-resolved spectra (see details in Li et al 2019). Because of the huge computational cost in each calculation and potential strong degeneracy between the parameters, a strict fitting procedure with the Bayesian method is not carried out in the current work.…”

Section: Application To Grb Datamentioning

confidence: 99%

“…Thus α may not be a good indicator to justify the radiation mechanism (Burgess et al 2015;Iyyani et al 2015;Meng et al 2018). It was found that there are two distinct evolution patterns for E p , i.e., hard-to-soft (Norris et al 1986) and intensity-tracking (Golenetskii et al 1983;Bhat et al 1994;Kargatis et al 1994;Ford et al 1995;Preece et al 2000;Lu et al 2010;Ghirlanda et al 2011;Lu et al 2012;Li et al 2019. In addition, Hakkila & Preece (2011) show that all single pulses GRBs could have the hard-to-soft evolution pattern.…”

Section: Introductionmentioning

confidence: 99%

Evolution Patterns of the Peak Energy in the GRB Prompt Emission

Gao,

Geng,

Huang

2021

Preprint

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Context. There are two different evolution patterns of the peak energy (E p ) exhibited during the prompt emission phase of gamma-ray bursts (GRBs), i.e., hard-to-soft and intensity-tracking, of which the physical origin remains unknown. Except for low-energy indices of GRB prompt spectra, the evolution patterns of E p may be another crucial indicator to discriminate radiation mechanisms (e.g., synchrotron or photosphere) for GRBs. Aims. We explore the parameter space to find conditions that could generate different evolution patterns of the peak energy in the framework of synchrotron radiation. Methods. We have developed a code to calculate the synchrotron emission from a simplified shell numerically, considering three cooling processes (synchrotron, synchrotron self-Compton (SSC), and adiabatic) of electrons, the effect of decaying magnetic field, the effect of the bulk acceleration of the emitting shell, and the effect of a variable source function that describes electrons accelerated in the emitting region. Results. After exploring the parameter space of the GRB synchrotron scenario, we find that the intensity-tracking pattern of E p could be achieved in two situations. One is that the cooling process of electrons is dominated by adiabatic cooling or SSC+adiabatic cooling at the same time. The other is that the emitting region is under acceleration in addition to the cooling process being dominated by SSC cooling. Otherwise, hard-to-soft patterns of E p are normally expected. Moreover, a chromatic intensity-tracking pattern of E p could be induced by the effect of a variable source function.

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“…After decades of researches, the radiation mechanism of GRB prompt emission is still unclear (e.g., Zhang & Yan 2011;Geng et al 2018Geng et al , 2019Lin et al 2018;Zhang et al 2018aZhang et al ,b, 2021Duan, & Wang 2019a,b;Huang et al 2019;Li et al 2019b;Yang et al 2020;Zhang 2020). The photospheric emission model seems to be a promising scenario (e.g., Abramowicz et al 1991;Thompson 1994;Mészáros & Rees 2000;Rees & Mészáros 2005;Pe'er & Ryde 2011;Fan et al 2012;Lazzati et al 2013;Ruffini et al 2013;Gao & Zhang 2015;Bégué & Pe'er 2015;Pe'er et al 2015;Ryde et al 2017;Acuner & Ryde 2018;Hou et al 2018;Meng et al 2018Meng et al , 2019Li 2019a,c,d;Acuner et al 2020;Wang et al 2020).…”

Section: Introductionmentioning

confidence: 99%

The Photosphere Emission Spectrum of Hybrid Relativistic Outflow for Gamma-ray Bursts

Meng,

Geng,

2021

Preprint

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The photospheric emission in the prompt phase is the natural prediction of the original fireball model for gamma-ray burst (GRB) due to the large optical depth (τ > 1) at the base of the outflow, which is supported by the quasi-thermal components detected in several Fermi GRBs. However, which radiation mechanism (photosphere or synchrotron) dominates in most GRB spectra is still under hot debate. The shape of the observed photosphere spectrum from a pure hot fireball or a pure Poynting-fluxdominated outflow has been investigated before. In this work, we further study the photosphere spectrum from a hybrid outflow containing both a thermal component and a magnetic component with moderate magnetization (σ 0 = L P /L Th ∼ 1 − 10), by invoking the probability photosphere model. The high-energy spectrum from such a hybrid outflow is a power law rather than an exponential cutoff, which is compatible with the observed Band function in large amounts of GRBs. Also, the distribution of the low-energy indices (corresponding to the peak-flux spectra) is found to be quite consistent with the statistical result for the peak-flux spectra of GRBs best-fitted by the Band function, with similar angular profiles of structured jet in our previous works. Finally, the observed distribution of the high-energy indices can be well understood after considering the different magnetic acceleration (due to magnetic reconnection and kink instability) and the angular profiles of dimensionless entropy with the narrower core.

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“Double-tracking” Characteristics of the Spectral Evolution of GRB 131231A: Synchrotron Origin?

Cited by 39 publications

References 99 publications

Probing into emission mechanisms of GRB 190530A using time-resolved spectra and polarization studies: Synchrotron Origin?

Probing into emission mechanisms of GRB 190530A using time-resolved spectra and polarization studies: Synchrotron Origin?

Evolution Patterns of the Peak Energy in the GRB Prompt Emission

The Photosphere Emission Spectrum of Hybrid Relativistic Outflow for Gamma-ray Bursts

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