Time-resolved GRB spectra in the complex radiation of synchrotron and Compton processes

Jiang, Yunguo; Hu, S.; Chen, X.; Li, K.; Guo, Dadong; Li, Y. T.; Li, H. Z.; You-Yuan, Zhao; Lin, Hai-Nan; Chang, Zhe

doi:10.1093/mnras/stv2870

Cited by 3 publications

(2 citation statements)

References 67 publications

(65 reference statements)

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“…In addition to modeling the time-integrated spectra analytically, the analyses on the time-resolved spectra of the prompt emission (e.g., Lu et al 2012;Zhang et al 2016;Jiang et al 2016) can also provide important information on the radiation process. On the other hand, the numerical method has the advantage over the analytical method in that it can incorporate different radiation mechanisms and can follow the evolution of physical properties in the emitting region.…”

Section: Introductionmentioning

confidence: 99%

Low-energy Spectra of Gamma-Ray Bursts from Cooling Electrons

Geng

Huang

et al. 2018

ApJS

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The low-energy spectra of gamma-ray bursts' (GRBs) prompt emission are closely related to the energy distribution of electrons, which is further regulated by their cooling processes. We develop a numerical code to calculate the evolution of the electron distribution with given initial parameters, in which three cooling processes (i.e., adiabatic, synchrotron and inverse Compton cooling) and the effect of decaying magnetic field are coherently considered. A sequence of results are presented by exploring the plausible parameter space for both the fireball and the Poynting-flux-dominated regime. Different cooling patterns for the electrons can be identified and they are featured by a specific dominant cooling mechanism. Our results show that the hardening of the low-energy spectra can be attributed to the dominance of synchrotron self-Compton cooling within the internal shock model, or to decaying synchrotron cooling within the Poynting-flux-dominated jet scenario. These two mechanisms can be distinguished by observing the hard low-energy spectra of isolated short pulses in some GRBs. The dominance of adiabatic cooling can also lead to hard low-energy spectra when the ejecta is moving at an extreme relativistic speed. The information from the time-resolved low-energy spectra can help to probe the physical characteristics of the GRB ejecta via our numerical results.

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Section: Introductionmentioning

confidence: 99%

Low-energy Spectra of Gamma-Ray Bursts from Cooling Electrons

Geng

Huang

et al. 2018

ApJS

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“…In the lepton models, the variation trends should be the same for V-band and γ-ray, since the radiative particles are the same population, and both two bands have the negative spectral indices. However, if the spectrum of radiative particles are evolved during the flare, a broken power law can be formed (Jiang et al 2016). The particles radiating γ-ray photons and the particles radiating V-band photons distributing at different energy range may have different variation trend.…”

Section: Variation Of Spectral Indexmentioning

confidence: 99%

A comprehensive study on the variation phenomena of AO 0235+164

Wang,

Jiang

2020

Preprint

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The variation mechanism of blazars is a long standing open question. The polarization observation can provide us with more information to constrain models. In this work, we collect the long term multi-wavelength data of AO 0235+164, and make correlation analysis between them by using the local cross-correlation function (LCCF). We found that both γ-ray and the optical V-band light curves are correlated with the radio light curve at beyond 3σ significance level. The emitting regions of the γ-ray and the optical coincide within errors, and locate at 6.6 +0.6 −1.7 pc upstream of the core region of 15 GHz, which are beyond the broad line region (BLR). The color index shows the redder when brighter (RWB) trend at the low flux state, but turns to the bluer when brighter (BWB) trend at the high flux state. While, the γ-ray spectral index always shows the softer when brighter (SWB) trend. We propose that such complex variation trends can be explained by the increasing jet component with two constant components. The optical PD flares and optical flux flares are not synchronous. It seems that one flux peak are sandwiched by two PD peaks, which have inverse rotation trajectories in the qu plane. The helical jet model can schematically show these characteristics of polarization with fine tuned parameters. The change of viewing angle is suggested to be the primary variable which lead all these variations, although other possibilities like the shock in jet model or the hadronic model are not excluded completely.

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A Comprehensive Study on the Variation Phenomena of AO 0235+164

Wang

Jiang

2020

ApJ

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The variation mechanism of blazars is a long-standing open question. Observations of polarization can provide us with more information to constrain models. In this work, we collect long-term multiwavelength data on AO 0235+164, and analyse the correlations between them by using the local cross-correlation function. We find that both γ-ray and the optical V-band light curves are correlated with the radio light curve beyond the 3σ significance level. The regions emitting the γ-ray and optical radiation coincide within errors, and are located pc upstream of the core region of 15 GHz, which is beyond the broad-line region. The color index shows the redder-when-brighter trend in the low flux state, but turns to the bluer-when-brighter trend in the high flux state, while the γ-ray spectral index always shows the softer-when-brighter trend. We propose that such complex variation trends can be explained by the increasing jet component with two constant components. The optical polarization degree (PD) flares and optical flux flares are not synchronous. It seems that one flux peak is sandwiched by two PD peaks, which have inverse rotation trajectories in the qu plane. The helical jet model can schematically show these characteristics of polarization with fine-tuned parameters. The change in viewing angle is suggested to be the primary variable that leads to all these variations, although other possibilities such as the shock-in-jet model or the hadronic model are not excluded completely.

show abstract

Time-resolved GRB spectra in the complex radiation of synchrotron and Compton processes

Cited by 3 publications

References 67 publications

Low-energy Spectra of Gamma-Ray Bursts from Cooling Electrons

Low-energy Spectra of Gamma-Ray Bursts from Cooling Electrons

A comprehensive study on the variation phenomena of AO 0235+164

A Comprehensive Study on the Variation Phenomena of AO 0235+164

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