A critical analysis of ideal magnetohydrodynamic models for crab-like pulsar winds

NCU Institutional Repository > 理學院 > 天文研究所 > 期刊論文 > Item 987654321/27902

jsp.display-item.identifier=請使用永久網址來引用或連結此文件: http://ir.lib.ncu.edu.tw/handle/987654321/27902

题名:	A critical analysis of ideal magnetohydrodynamic models for crab-like pulsar winds
作者:	Chiueh,T;Li,ZY;Begelman,MC
贡献者:	天文研究所
关键词:	DRIVEN RELATIVISTIC JETS;MAGNETIC-FIELD;NEBULA;FLOWS
日期:	1998
上传时间:	2010-06-29 19:35:48 (UTC+8)
出版者:	中央大學
摘要:	We present a critical examination of the ideal MHD model far the stationary Crab pulsar wind, which has a terminal flow Lorentz factor gamma(infinity) similar to 10(6) and may have a terminal ratio of Poynting flux to kinetic energy flux as low as sigma similar to 10(-2)-10(-3). We first show that transitions to a low-sigma configuration cannot occur gradually in regions well beyond the light cylinder where the flow has already become ultrarelativistic. This is because the poloidal field lines do not expand sufficiently beyond the fast critical point to convert the electromagnetic energy into flow kinetic energy. As an alternative, we consider whether the acceleration may proceed abruptly, with the flow rapidly passing through the fast critical point and expanding into a low-sigma configuration. Such rapid expansion of held lines, analogous to that in a de Laval nozzle, requires the poloidal fields to be highly compressed upstream of the fast critical point. We categorize the rapid field expansion generally into two prototypes: sheetlike and fountain-like, with the former being a spontaneous transition and the latter requiring external pressure supports. Unfortunately, it is shown that both types of rapid acceleration fail to satisfy either the energy and momentum conservation or the MHD flux-freezing condition. Nevertheless, we have pinned down the only situation where a stationary, ideal-MHD low-sigma wind may exist. It requires almost the entire wind acceleration to occur in the immediate neighborhood of the light cylinder. Moreover, it also demands drastic modifications to the conventional picture of the pulsar dipole magnetosphere, in that the outer magnetosphere must be dominated by the toroidal fields and that the pulsar wind is carried by only a small fraction of the magnetospheric field lines emerging from the star.
關聯:	ASTROPHYSICAL JOURNAL
显示于类别:	[天文研究所] 期刊論文

文件中的档案:

档案	描述	大小	格式	浏览次数
index.html		0Kb	HTML	493	检视/开启

在NCUIR中所有的数据项都受到原著作权保护.

社群 sharing

数据加载中.....