Pulsar X-Ray and Gamma-Ray Pulse Profiles: Constraint on Obliquity and Observer Angles
Pulsar X-Ray and Gamma-Ray Pulse Profiles: Constraint on Obliquity and Observer Angles
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脉冲星 X 射线和伽马射线脉冲轮廓：倾斜度和观察者角度的约束
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
A. Muslimov
中科院分区：
文献类型：
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作者：
A. Harding;A. Muslimov
我们对Geminga、Vela和PSR 0656+14的热X射线剖面进行了建模，它们也被探测为γ射线源，以约束再现所观察到的X射线脉冲分数和脉冲宽度所需的相位空间和观察者角度。这些来自X射线光变曲线的几何约束条件进行了探索，为各种假设的表面温度分布和磁通量各向异性所造成的磁化大气。我们包括弯曲的时空对光子轨迹和磁场的影响。所观测到的γ射线脉冲轮廓是双峰，峰间的相位分离为0.4-0.5。假设γ射线分布是由以磁极为中心的空心圆锥体中的发射引起的，我们推导出对于不同的γ射线束尺寸，产生所观察到的γ射线峰值相位分离所需的对相位空间的约束条件和观察者角度。我们比较了X射线发射和γ射线脉冲观测的约束条件，发现重叠相空间要求入射角和观测角都小于20° ~ 30 °，这意味着γ射线束的张角最大为30° ~ 35 °。
We model the thermal X-ray profiles of Geminga, Vela, and PSR 0656+14, which have also been detected as γ-ray pulsars, to constrain the phase space of obliquity and observer angles required to reproduce the observed X-ray pulsed fractions and pulse widths. These geometrical constraints derived from the X-ray light curves are explored for various assumptions about surface temperature distribution and flux anisotropy caused by the magnetized atmosphere. We include curved spacetime effects on photon trajectories and the magnetic field. The observed γ-ray pulse profiles are double peaked with phase separations of 0.4-0.5 between the peaks. Assuming that the γ-ray profiles are due to emission in a hollow cone centered on the magnetic pole, we derive the constraints on the phase space of obliquity and observer angles, for different γ-ray beam sizes, required to produce the observed γ-ray peak phase separations. We compare the constraints from the X-ray emission to those derived from the observed γ-ray pulse profiles and find that the overlapping phase space requires both obliquity and observer angles to be smaller than 20°-30°, implying γ-ray beam opening angles of at most 30°-35°.