X-ray polarimetry of X-ray pulsar X Persei: another orthogonal rotator?
X-ray polarimetry of X-ray pulsar X Persei: another orthogonal rotator?
复制标题
X射线脉冲星X Persei的X射线偏振测量：另一个正交旋转体？
DOI：
10.1093/mnras/stad1961
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发表时间：
2023
影响因子：
4.8
通讯作者：
Lutovinov, A A
中科院分区：
文献类型：
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作者：
Mushtukov, A A;Tsygankov, S S;Poutanen, J;Doroshenko, V;Salganik, A;Costa, E;Marco, A Di;Heyl, J;Monaca, F La;Lutovinov, A A
英仙座X星是Be双星系统中的一颗周期为10835 s的持久低光度X射线脉冲星。中子星星表面的磁场强度并不精确，但间接迹象表明磁场超过1013 G，这使得该物体成为已知磁化最强的X射线天体之一。在这里，我们提出的观测结果X英仙座进行了成像X射线偏振探测器（IXPE）。X射线偏振信号被发现强烈依赖于脉冲星的自旋相位。在3-8千电子伏波段的能量平均偏振度变化从几个到百分之二十的脉冲与相位依赖类似的脉冲轮廓。偏振角显示出显着的变化，并使两个完整的旋转期间的脉冲周期，导致几乎为零的脉冲相位平均偏振。将旋转矢量模型应用于IXPE数据，我们获得了旋转轴倾角及其在天空中的位置角以及磁倾角的估计。推导出的倾角接近轨道倾角，较早报道的英仙座X。偏振数据暗示旋转轴和磁偶极轴之间有一个很大的角度，这与最近报道的X射线脉冲星GRO J1008−57的结果相似。在用最佳拟合旋转矢量模型消除偏振角旋转对脉冲星相位的影响后，发现脉冲星的偏振度与能量有很强的依赖关系，其值从0.2keV时的0增加到8 keV时的30%。
X Persei is a persistent low-luminosity X-ray pulsar of period of ≈ 835 s in a Be binary system. The field strength at the neutron star surface is not known precisely, but indirect signs indicate a magnetic field above 1013G, which makes the object one of the most magnetized known X-ray pulsars. Here we present the results of observations X Persei performed with theImaging X-ray Polarimetry Explorer(IXPE). The X-ray polarization signal was found to be strongly dependent on the spin phase of the pulsar. The energy-averaged polarization degree in 3–8 keV band varied from several to ∼20 per cent over the pulse with a phase dependence resembling the pulse profile. The polarization angle shows significant variation and makes two complete revolutions during the pulse period, resulting in nearly nil pulse-phase averaged polarization. Applying the rotating vector model to theIXPEdata we obtain the estimates for the rotation axis inclination and its position angle on the sky, as well as for the magnetic obliquity. The derived inclination is close to the orbital inclination, reported earlier for X Persei. The polarimetric data imply a large angle between the rotation and magnetic dipole axes, which is similar to the result reported recently for the X-ray pulsar GRO J1008−57. After eliminating the effect of polarization angle rotation over the pulsar phase using the best-fitting rotating vector model, the strong dependence of the polarization degree with energy was discovered, with its value increasing from 0 at ∼2 keV to 30per cent at 8 keV.