Early afterglows from radially structured outflows and the application to X-ray shallow decays

	Early afterglows from radially structured outflows and the application to X-ray shallow decays
	Liu, Xue-Wen 1,2,3; Wu, Xue-Feng1,3,4 ; Zou, Yuan-Chuan 5; Lu, Tan1,3
刊名	RESEARCH IN ASTRONOMY AND ASTROPHYSICS
	2009-08-01
卷号	9 期号:8 页码:911-920
关键词	gamma-rays: bursts hydrodynamics radiation mechanisms: nonthermal shock waves
英文摘要	In the fireball model, it is more physically realistic that gamma-ray burst (GRB) ejecta have a range of bulk Lorentz factors (assuming M proportional to Gamma(-s)). The low Lorentz factor part of the ejecta will catch up with the high Lorentz factor part when the latter is decelerated by the surrounding medium to a comparable Lorentz factor. Such a process will develop a long-lasting weak reverse shock until the whole ejecta are shocked. Meanwhile, the forward shocked materials are gradually supplied with energy from the ejecta that are catching-up, and thus the temporal decay of the forward shock emission will be slower than that without an energy supply. However, the reverse shock may be strong. Here, we extend the standard reverse-forward shock model to the case of radially nonuniform ejecta. We show that this process can be classified into two cases: the thick shell case and the thin shell case. In the thin shell case, the reverse shock is weak and the temporal scaling law of the afterglow is the same as that in Sari & Meszaros (2000). However, in the thick shell case, the reverse shock is strong and thus its emission dominates the afterglow in the high energy band. Our results also show slower decaying behavior of the afterglow due to the energy supply by low Lorentz factor materials, which may help the understanding of the plateau observed in the early optical and X-ray afterglows.
学科主题	Astronomy & Astrophysics
WOS标题词	Science & Technology ; Physical Sciences
类目[WOS]	Astronomy & Astrophysics
研究领域[WOS]	Astronomy & Astrophysics
关键词[WOS]	BURST AFTERGLOWS ; OPTICAL FLASH ; REVERSE-SHOCK ; LIGHT CURVES ; THEORETICAL IMPLICATIONS ; WIND ENVIRONMENTS ; LORENTZ FACTOR ; SWIFT ERA ; MODELS ; FIREBALLS
收录类别	SCI
语种	英语
WOS记录号	WOS:000269166200007
公开日期	2015-04-14
内容类型	期刊论文
源URL	[http://libir.pmo.ac.cn/handle/332002/10964]
专题	紫金山天文台_院士文集_陆埮
作者单位	1.Chinese Acad Sci, Purple Mt Observ, Nanjing 210008, Peoples R China 2.Chinese Acad Sci, Grad Univ, Beijing 100049, Peoples R China 3.Joint Ctr Particle Nucl Phys & Cosmol JCPNPC, Nanjing 210093, Peoples R China 4.Penn State Univ, Dept Astron & Astrophys, University Pk, PA 16802 USA 5.Huazhong Univ Sci & Technol, Dept Phys, Wuhan 430074, Peoples R China
推荐引用方式 GB/T 7714	Liu, Xue-Wen,Wu, Xue-Feng,Zou, Yuan-Chuan,et al. Early afterglows from radially structured outflows and the application to X-ray shallow decays[J]. RESEARCH IN ASTRONOMY AND ASTROPHYSICS,2009,9(8):911-920.
APA	Liu, Xue-Wen,Wu, Xue-Feng,Zou, Yuan-Chuan,&Lu, Tan.(2009).Early afterglows from radially structured outflows and the application to X-ray shallow decays.RESEARCH IN ASTRONOMY AND ASTROPHYSICS,9(8),911-920.
MLA	Liu, Xue-Wen,et al."Early afterglows from radially structured outflows and the application to X-ray shallow decays".RESEARCH IN ASTRONOMY AND ASTROPHYSICS 9.8(2009):911-920.