论文标题
在不寻常的旋转期间，风馈X射线Pulsar Vela X-1中积聚磁盘的光谱证据
Spectral evidence of an accretion disk in wind-fed X-ray pulsar Vela X-1 during an unusual spin-up period
论文作者
论文摘要
在经典的超级X射线二进制文件（SGXB）中，通常假定Bondi-Hoyle-Lyttleton风力吸积，并且向增生器的角动量转运效率低下。在SGXBS中观察到的中子星的旋转/旋转行为尚不清楚。在本文中，我们报告了Vela X-1的延长状态（在轨道阶段0.16-0.2），持续至少30 ks，在异常旋转期开始时与Chandra观察到。在这种低状态下，与前面的耀斑相比，连续通量下降了10倍，而连续脉动几乎消失了。同时，低状态的Fe k $α$通量与前面的耀斑时期相似，导致Fe k $α$等效宽度（EW）为0.6 keV，高达VELA X-1的EclipSe阶段的Fe K $α$ ew。脉动戒烟和高fe k $α$ ew均表明轴对称结构，其圆柱密度大于$ 10^{24} \ rm cm^{ - 2} $，在VELA X-1的积聚半径上。这些现象与产生磁盘的存在是一致的，该磁盘会导致vela X-1的以下旋转。这表明磁盘积聚虽然并非总是如此，但确实发生在经典的风馈SGXB中。
In classical supergiant X-ray binaries (SgXBs), the Bondi-Hoyle-Lyttleton wind accretion was usually assumed, and the angular momentum transport to the accretors is inefficient. The observed spin-up/spin-down behavior of the neutron star in SgXBs is not well understood. In this paper, we report an extended low state of Vela X-1 (at orbital phases 0.16-0.2), lasting for at least 30 ks, observed with Chandra during the onset of an unusual spin-up period. During this low state, the continuum fluxes dropped by a factor of 10 compared to the preceding flare period, and the continuum pulsation almost disappeared. Meanwhile, the Fe K$α$ fluxes of the low state were similar to the preceding flare period, leading to an Fe K$α$ equivalent width (EW) of 0.6 keV, as high as the Fe K$α$ EW during the eclipse phase of Vela X-1. Both the pulsation cessation and the high Fe K$α$ EW indicate an axisymmetric structure with a column density larger than $10^{24}\rm cm^{-2}$ on a spatial scale of the accretion radius of Vela X-1. These phenomena are consistent with the existence of an accretion disk that leads to the following spin-up of Vela X-1. It indicates that disk accretion, although not always, does occur in classical wind-fed SgXBs.
