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arXiv 1402.6324astro-ph.HE
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XSS J12270-4859在新低态的X射线观测:一个向无扰动旋转动力脉冲双星的转变

X-ray Observations of XSS J12270-4859 in a New Low State: A Transformation to a Disk-Free Rotation-Powered Pulsar Binary

Slavko Bogdanov, Alessandro Patruno, Anne M. Archibald, Cees Bassa, Jason W. T. Hessels, Gemma H. Janssen, Ben W. Stappers

摘要:

我们提出了XMM-牛顿和钱德拉观测的低质量X射线二进制XSS J12270--4859,经历了一个戏剧性的下降,光学/X射线亮度在2012年底,表明其吸积盘的消失。在这种新的状态下,系统表现出以前没有轨道相位相关的,大振幅的X射线调制与下降的通量在优越的结合。X射线的发射仍然主要是非热的,但具有一个数量级较低的平均光度和显着更硬的光谱相对于以前的高通量状态。这种现象与射电毫秒脉冲星双星PSR J 1023 +0038在没有吸积盘的情况下的行为相同,其中X射线发射是在脉冲星风驱动的双星内激波中产生的。这进一步表明XSS J12270-4859不再有一个吸积盘,并已转变为一个成熟的食“红背”系统,拥有一个活跃的旋转动力毫秒脉冲星。没有证据表明双星系统的弥漫性X射线发射可能是由外流或风星云引起的。距离XSS J12270--4859 1. 5 '的扩展源不太可能是相关的,可能是以前未编目的星系团。

英文摘要:

We present XMM-Newton and Chandra observations of the low-mass X-ray binary XSS J12270--4859, which experienced a dramatic decline in optical/X-ray brightness at the end of 2012, indicative of the disappearance of its accretion disk. In this new state, the system exhibits previously absent orbital-phase-dependent, large-amplitude X-ray modulations with a decline in flux at superior conjunction. The X-ray emission remains predominantly non-thermal but with an order of magnitude lower mean luminosity and significantly harder spectrum relative to the previous high flux state. This phenomenology is identical to the behavior of the radio millisecond pulsar binary PSR J1023+0038 in the absence of an accretion disk, where the X-ray emission is produced in an intra-binary shock driven by the pulsar wind. This further demonstrates that XSS J12270-4859 no longer has an accretion disk and has transformed to a full-fledged eclipsing "redback" system that hosts an active rotation-powered millisecond pulsar. There is no evidence for diffuse X-ray emission associated with the binary that may arise due to outflows or a wind nebula. An extended source situated 1.5' from XSS J12270--4859 is unlikely to be associated, and is probably a previously uncatalogued galaxy cluster.

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