Polarization Evolution of Early Optical Afterglows of Gamma-Ray Bursts

Lan, Mi-Xiang; Wu, Xue-Feng; Dai, Zhuojun

doi:10.3847/0004-637x/816/2/73

Cited by 35 publications

(80 citation statements)

References 49 publications

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“…If POLAR is launched, the GRB polarimetric data will be significantly enlarged, and the statistical significance will be highly improved. In the theoretical aspect, several theoretical models have been proposed to explain the GRB polarization (Sari 1999;Waxman 2003;Granot 2003;Lazzati et al 2004;Toma et al 2009;Mao & Wang 2013;Chang, Jiang & Lin 2014;Chang & Lin 2014a,b;Lan, Wu & Dai 2016).…”

Section: Introductionmentioning

confidence: 99%

Gamma-ray burst polarization reduction induced by the Lorentz invariance violation

Lin

Chang

2016

Mon. Not. R. Astron. Soc.

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It has been observed that photons in the prompt emission of some gamma-ray bursts (GRBs) are highly polarized. The high polarization is used by some authors to give a strict constraint on the Lorentz invariance violation (LIV). If the Lorentz invariance is broken, the polarization vector of a photon may rotate during its propagation. The rotation angle of polarization vector depends on both the photon energy and the distance of source. It is believed that if high polarization is observed, then the relative rotation angle (denoted by α) of polarization vector of the highest energy photon with respect to that of the lowest energy photon should be no more than π/2. Otherwise, the net polarization will be severely suppressed, thus couldn't be as high as what was actually observed. In this paper, we will give a detailed calculation on the evolution of GRB polarization arising from LIV effect duration the propagation. It is shown that the polarization degree rapidly decrease as α increases, and reaches a local minimum at α ≈ π, then increases until α ≈ 3π/2, after that decreases again until α ≈ 2π, etc. The polarization degree as a function of α oscillates with a quasi-period T ≈ π, while the oscillating amplitude gradually decreases to zero. Moreover, we find that a considerable amount (more than 60% of the initial polarization) of polarization degree can be conserved when α ≈ π/2. The polarization observation in a higher and wider energy band, a softer photon spectrum, and a higher redshift GRB is favorable in order to tightly constrain LIV effect.

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Section: Introductionmentioning

confidence: 99%

Gamma-ray burst polarization reduction induced by the Lorentz invariance violation

Lin

Chang

2016

Mon. Not. R. Astron. Soc.

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“…They simply consider an emitting shell with a constant velocity, which starts to radiate at R s and turns off at R of f , to generate the light curve of GRB prompt emission. The MFC is assumed to be a large-scale ordered toroidal magnetic field, and the change in PA with this MFC will only be abrupt 90 • change (Lan et al 2016). The common features of their PD evolution are the PD plateau and steep decay part after the turn-off time of a GRB pulse t of f .…”

Section: Conclusion and Discussionmentioning

confidence: 99%

“…Time-integrated and energy-integrated polarization will erase the evolution information of polarization, which will be important for constraining the physical process of the GRB prompt phase. For example, a gradually evolving PA with time or energy will indicate an aligned magnetic field component in the jet and correspond to a magnetar-driven GRB (Lan et al 2016;. Recently, time-resolved polarization of GRB 170114A was analyzed by Burgess et al (2019).…”

Section: Introductionmentioning

confidence: 99%

Polarization Predictions in the GRB Prompt Phase with the Internal Shock Model

Lan,

Wang,

et al. 2021

Preprint

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As the standard gamma-ray burst (GRB) prompt-emission model, the internal shock (IS) model can reproduce the fast-rise and slow-decay features of the pulses in the GRB light curve. The time-and energy-dependent polarization can deliver important physical information on the emission region and can be used to test models. Polarization predictions for the GRB prompt phase with the magnetized IS model should be investigated carefully. The magnetic field of the magnetized IS model is very likely to be mixed and decays with radius. The synchrotron emission in the presence of such a decaying magnetic field can recover the Band-like spectrum of the GRB prompt phase. We investigate the dependence of the polarization of GRB prompt emission on both time and energy in the framework of the magnetized IS model. Due to the large range of parameters, it is hard to distinguish the magnetized IS model and the magnetic-reconnection model through polarization degree (PD) curves. The energy-dependent PD could increase toward the high-energy band for the magnetized IS model, while it decreases to zero above the megaelectronvolt band for the dissipative photosphere model. Therefore, we conclude that the energy dependence of PD can be used to distinguish these two models for the GRB prompt emission. Finally, we find that, independent of the observational energy band, the profiles of the ξ B −P D curve for the time-integrated and time-resolved PDs are very similar, where ξ B is the magnetic field strength ratio of the ordered component to the random component.

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“…近年来的研究表明高红移处由伽玛暴推断的恒星形成率要高于由高红移星系得到的恒星形成率 [97,105] , 这可能归结于金属丰度演化 [97] 、初始质量函数的演化 [91] 、光度函数的演化 [106] 等. [107] 和内禀模型 [108,109] . Zhang和Yan [110] 在2011年提出了伽玛暴瞬时辐射的"内激波诱导磁重联"(ICMART)模型, 并预言了偏振度在单个伽玛暴脉冲演化过程中呈现衰减行为. Dai [111] 在2004年提出相对论星风泡模型来解释伽玛暴X射线余辉的平台, 并预言X射线平台期会有较高的线偏振度; Lan等人 [108] 基于该模型, 详细给出了不同对称性模型下X射线平台期线偏振的演化; Wu等人 [107] 在2005年研究了双成分喷流模型下伽玛暴光学余辉的偏振演化; Lan等人 [109] [112] , 但是后来发现这个结果不正确；在GRB100826A的瞬时辐射中首次观测到了偏振方位角有剧烈改变 [113] ; 在GRB090102的光学余辉中首次探测到了反向激波区域辐射的线偏振达到10% [114] ; 在GRB120308A的光学余辉中首次探测到了辐射由反向激波主导到正向激波主导过度期间的偏振 [115] ; 在GRB121024A的光学余辉中首次观测到了来自正向激波区域辐射的(0.61 ± 0.13)%的圆偏振 [116] .…”

Section: 高高高红红红移移移恒恒恒星星星形形形成成成率率率unclassified