A propeller scenario for the gamma-ray emission of low-mass X-ray binaries: the case of XSS J12270−4859
A propeller scenario for the gamma-ray emission of low-mass X-ray binaries: the case of XSS J12270−4859
复制标题
DOI：
10.1093/mnras/stt2336
复制
发表时间：
2013-12
影响因子：
4.8
通讯作者：
A. Papitto;D. Torres;Jian Li
中科院分区：
文献类型：
--
作者：
A. Papitto;D. Torres;Jian Li
XSS J12270 - 4859是唯一的低质量X射线双星（LMXB），在费米-LAT域2FGL 1227.7 - 4853中提出了持久伽马射线对应物。在这里，我们提出了最近的积分观测的分析结果，旨在评估硬X射线发射的长期变化，从而吸积状态的稳定性。我们确认，源的行为作为一个持久的硬X射线发射器之间的2003年和2012年。我们提出XSS J12270 - 4859拥有一颗处于螺旋桨状态的中子星星，我们详细研究了这种状态，开发了一个理论模型来重现相关的X射线和伽马射线特性。这个模型可以被理解为一个更一般的性质，代表一个可行的替代方案，LMXB可以出现作为伽马射线源。特别是，这可能适用于毫秒脉冲星执行从由其磁场旋转提供动力的状态到由物质下落提供动力的状态的转变的情况，例如最近从过渡脉冲星PSR J1023+0038观察到的情况。虽然LMXB中典型NS的表面磁场比伴随着高质量双星的中子星的更强磁场低四个数量级以上，但NS-LMXB系统中物质流被截断的半径要低得多。磁层界面的磁场在这个界面上要大几个数量级，因此，加速电子的功率也大。我们表明，冷却的加速电子人口发生主要是通过同步辐射相互作用与磁场渗透的接口，并通过逆康普顿损失由于电子和同步辐射光子之间的相互作用，他们发射。我们发现自同步康普顿过程可以解释XSS J12270 - 4859的高能现象。
XSS J12270‐4859 is the only low mass X-ray binary (LMXB) witha proposed persistent gamma-ray counterpart in the Fermi-LAT domain, 2FGL 1227.7‐4853. Here, we present the results of the analysis of recent INTEGRAL observations, aimed at assessing the long-term variability of the hard X-ray emission, and thus the stabili ty of the accretion state. We confirm that the source behaves as a persistent hard X-ray emitter between 2003 and 2012. We propose that XSS J12270‐4859 hosts a neutron star in a propeller state, a state we investigate in detail, developing a theoretical model to reproduce the associated X-ray and gamma-ray properties. This model can be understood as being of a more general nature, representing a viable alternative by which LMXBs can appear as gamma-ray sources. In particular, this may apply to the case of millisecond pulsars performing a transition fro m a state powered by the rotation of their magnetic field, to a state powered by matter in-fall, su ch as that recently observed from the transitional pulsar PSR J1023+0038. While the surface magnetic field of a typical NS in a LMXB is lower by more than four orders of magnitude than the much more intense fields of neutron stars accompanying high-mass binaries, the radius at which the matter in-flow is truncated in a NS-LMXB system is much lower. The magnetic field at the magnetospheric interface is then orders of magnitude larger at this interface , and as consequence, so is the power to accelerate electrons. We demonstrate that the cooling of the accelerated electron population takes place mainly through synchrotron interaction with the magnetic field permeating the interface, and through inverse Compton losses due to the interaction between the electrons and the synchrotron photons they emit. We found that self-synchrotron Compton processes can explain the high energy phenomenology of XSS J12270‐4859.