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中国天文学会学术期刊

天文学进展

PROGRESS IN ASTRONOMY

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反常X射线脉冲星的研究进展

陈蕊 ^1,2 李向东 ²
(1 北京大学天文系北京 100871)
(2 南京大学天文系南京 210093)

摘要

反常X射线脉冲星(Anomalous X-ray Pulsars, 简称AXP)是一类特殊的X射线源。与X射线脉冲星(通常处于大质量X射线双星系统中)相比，它们具有以下特征：X射线谱较软、光度低而稳定( » 10²⁷~ 10²⁹Js^-1 )、自转周期集中在10s左右且稳定增长、迄今没有找到它们的光学、红外、射电的对应体、有一些可能与超新星遗迹成协等。由观测到的自转周期变化可以确定它们的自转能损不足以提供其X射线辐射。解释AXP能源机制的理论模型目前主要有两大类：在吸积模型中，AXP被认为是具有正常磁场强度( »10⁸T )的中子星，物质吸积提供X射线辐射的能源，并造成中子星的自转变化；另一种观点认为AXP是具有超强磁场( » 10¹⁰~ 10¹¹T )的中子星(即磁星)，其辐射能源来自它们巨大的磁场能或残余的热能，观测到的自转周期及其变化被归因于中子星的磁偶极辐射和物质抛射。两种模型各有优缺点，但目前看来观测事实对磁星模型较为有利。为了进一步明确AXP的性质，提供解释它们能源机制的线索，在介绍AXP的基本观测特征和理论解释的基础上，还将AXP与射电脉冲星、特强磁场射电脉冲星、射电宁静脉冲星候选体及软g 射线复现源分别进行了比较。

The Anomalous X-ray Pulsars

Chen Rui ^1,2 Li Xiangdong ²
(1 Department of Astronomy, Peking University, Beijing 100871)
(2 Department of Astronomy, Nanjing University, Nanjing 210093)

Abstract

In the last few years it has been recognized that a group of X-ray pulsars have peculiar properties which set them apart from the majority of accreting pulsars in X-ray binaries. They are called the Anomalous X-ray Pulsars (AXP). These objects are characterized by very soft X-ray spectra with low and steady X-ray fluxes, narrow-distributed spin periods, steady spin-down, no optical/infrared counterparts. Some of them may associate with supernova remnants. The nature of AXP remains mysterious. It has been suggested that AXP are accreting neutron stars, or solitary “magnetars”, neutron stars with super strong magnetic fields (» 10¹⁰~ 10¹¹T). In this paper we review the recent progress in the studies of AXP, and discuss the possible implications from comparison of AXP with other neutron stars, such as radio pulsars, radio quiet X-ray pulsar candidates and soft g-ray repeaters.