The polarization-Angle flip in GRB prompt emission

doi:10.1051/0004-6361/202348050

YNAO OpenIR > 星系类星体研究组

	The polarization-Angle flip in GRB prompt emission
	Cheng, Kangfa 1; Zhao XH(赵晓红)2,3,4 ; Mao JR(毛基荣)2,3,4 ; Chen, Zhifu 1
发表期刊	ASTRONOMY & ASTROPHYSICS
	2024-07-03
卷号	687
DOI	10.1051/0004-6361/202348050
产权排序	第2完成单位
收录类别	SCI
关键词	magnetic fields polarization radiation mechanisms: non-thermal relativistic processes stars: jets gamma rays: stars
摘要	Context. In recent years, some polarization measurements of gamma-ray bursts (GRBs) have been reported, and the polarization-angle (PA) rotation in the prompt emission phase has been found in several bursts. The physical mechanism of the PA evolution is still unclear. In this work, we studied the origin of the PA rotation in a toroidal magnetic field. Aims. We aim to provide an explanation for the PA rotation in GRBs and find the physical conditions that lead to the rotation by 90 degrees in the toroidal magnetic-field (MF) model. Moreover, we present some observable polarization properties in the MF model that can be tested in the future. Methods. We calculated the instantaneous polarization degree (PD) from a top-hat jet with different normalized viewing angles (q = theta(v)/theta(j)), jet opening angles (theta(j)), and jet Lorentz factors (Gamma) in three wavebands. When the PD changes between positive and negative values, it means that the PA flips by 90 degrees. On these grounds, we can summarize the range of parameters required for these PA flips. Considering these parameter conditions, we can further estimate the observed rate of the GRBs exhibiting such PA rotations. Results. We find that the PA rotation in the toroidal MF is primarily related to three critical factors: the viewing angle, the jet opening angle, and the jet Lorentz factor. Additionally, the PA can experience flips of 90 degrees twice. The conditions for the flips are q greater than or similar to 0.5 (except for q similar or equal to 1) and y(j) = (Gamma theta(j))(2) greater than or similar to 4. However, the two flips in the PA might not be concurrently observable due to the constraint of flux. Taking these conditions into account and assuming a random orientation between the jet axis and the line of sight (LOS), we obtain a theoretical upper limit (without any constraints) for the observed rate of GRBs in the X-ray or gamma-ray band displaying the flips in PA as R-ch less than or similar to 80%. We further constrain the observed rate as R-ch similar to 16% according to the maximal post-flip polarized flux level, where the observed rate of single and double flips each account for similar to 8%. It should be noted that the observed rates are different in various wavebands. The observed rate of the second PA flip in the optical bands should be higher than that in the X-ray or gamma-ray band since the flux in the optical band declines much slower than that in the X-ray or gamma-ray band. Moreover, when the LOS is close to the jet edge (q -> 1), it is the easiest case in which to observe the 90-degree PA flip due to the relatively high post-flip polarized flux level. The first and second PA flips in a GRB pulse are most likely to occur at the observed times of t(obs) similar to [2 - 3]t(peak) and similar to[3 - 4]t(peak), respectively, where t(peak) is the peak time of the pulse. It is also noted that the PA flip would not happen before the peak time.
资助项目	Guangxi Natural Science Foundation[GUIKEAD22035945]; Guangxi Natural Science Foundation[2024GXNSFBA010350]; Guangxi Natural Science Foundation[2019GXNSFFA245008]; Scientific Research Project of Guangxi Minzu University[2021KJQD03]; National Key R&D Program of China[2023YFE0101200]; National Natural Science Foundation of China[U1831135]; National Natural Science Foundation of China[12393813]; National Natural Science Foundation of China[12393811]; Yunnan Revitalization Talent Support Program (YunLing Scholar Project)
项目资助者	Guangxi Natural Science Foundation[GUIKEAD22035945, 2024GXNSFBA010350, 2019GXNSFFA245008] ; Scientific Research Project of Guangxi Minzu University[2021KJQD03] ; National Key R&D Program of China[2023YFE0101200] ; National Natural Science Foundation of China[U1831135, 12393813, 12393811] ; Yunnan Revitalization Talent Support Program (YunLing Scholar Project)
语种	英语
学科领域	天文学 ; 星系与宇宙学
文章类型	Article
出版者	EDP SCIENCES S A
出版地	17, AVE DU HOGGAR, PA COURTABOEUF, BP 112, F-91944 LES ULIS CEDEX A, FRANCE
ISSN	0004-6361
URL	查看原文
WOS记录号	WOS:001270393900005
WOS研究方向	Astronomy & Astrophysics
WOS类目	Astronomy & Astrophysics
关键词[WOS]	GAMMA-RAY BURST ; INDUCED MAGNETIC RECONNECTION ; SYNCHROTRON POLARIZATION ; JITTER RADIATION ; FIELD ; AFTERGLOW ; SHOCK
EI入藏号	20242816679316
EI主题词	Polarization
EI分类号	657.2 Extraterrestrial Physics and Stellar Phenomena - 701.2 Magnetism: Basic Concepts and Phenomena - 931.1 Mechanics - 931.3 Atomic and Molecular Physics - 932.1 High Energy Physics
引用统计	被引频次：3[WOS] [WOS记录] [WOS相关记录]
文献类型	期刊论文
条目标识符	http://ir.ynao.ac.cn/handle/114a53/27462
专题	星系类星体研究组中国科学院天体结构与演化重点实验室
作者单位	1.School of Mathematics and Physics, Guangxi Minzu University, Nanning 530006, PR China; 2.Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011, PR China; 3.Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Science, Kunming 650011, PR China; 4.Center for Astronomical Mega-Science, Chinese Academy of Science, 20A Datun Road, Chaoyang District, Beijing 100012, PR China
推荐引用方式 GB/T 7714	Cheng, Kangfa,Zhao XH,Mao JR,et al. The polarization-Angle flip in GRB prompt emission[J]. ASTRONOMY & ASTROPHYSICS,2024,687.
APA	Cheng, Kangfa,赵晓红,毛基荣,&Chen, Zhifu.(2024).The polarization-Angle flip in GRB prompt emission.ASTRONOMY & ASTROPHYSICS,687.
MLA	Cheng, Kangfa,et al."The polarization-Angle flip in GRB prompt emission".ASTRONOMY & ASTROPHYSICS 687(2024).

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