论文标题
使用时间分配的无线电和伽玛射线脉冲曲线来限制毫秒的脉冲星几何形状
Constraining millisecond pulsar geometry using time-aligned radio and gamma-ray pulse profile
论文作者
论文摘要
自Fermi Gamma-ray太空望远镜推出以来，已经发现了数百个伽马射线脉冲星，有些是无线电大声的，有些是带有时间对齐的无线电和伽马射线光曲线的无线电广播。在第二次费米Pulsar目录中，根据大面积望远镜在费米卫星上收集的三年数据报告了117个新的伽马射线脉冲星，提供了大量信息，例如峰值分离〜$Δ$ gamma-ray脉动和无线电滞后和无线电lag $δ$δ$δ$δ$δ$δ$δ$δ$δ$ quamma-ray and pulse pulses＆puresa-ray and pulses pulses＆pure pulsesses。我们选择了几个无线电台毫秒伽马射线脉冲星，其周期为〜$ p $在2-6〜ms的范围内，并在其伽马射线轮廓上显示了双峰。我们试图限制其磁层的几何形状，即每个系统的磁轴和视线倾斜角。我们将无力的偶极磁层从恒星表面施加到条纹风区域（远远超过光缸），以适合伽马射线中观察到的脉冲曲线，并与它们与无线电轮廓的相位保持一致。在确定拟合曲线是否合理的过程中，我们采用了一种最小二乘方法将观察到的伽马射线强度与我们的模型中的强度进行比较，强调了伽马射线峰的幅度，它们的分离以及无线电和伽马射线峰之间的相位滞后。我们获得了最佳拟合和合理的参数，与观察到十毫秒脉冲星的观察结果一致。最终，我们限制了由磁性倾斜度〜$α$和视觉倾斜度〜$ζ$描述的每个脉冲星的几何形状。我们发现两个角度都大于〜$ 45^{\ rm o} $。
Since the launch of the Fermi Gamma-Ray Space Telescope, several hundred gamma-ray pulsars have been discovered, some being radio-loud and some radio-quiet with time-aligned radio and gamma-ray light curves. In the second Fermi Pulsar Catalogue, 117 new gamma-ray pulsars have been reported based on three years of data collected by the Large Area Telescope on the Fermi satellite, providing a wealth of information such as the peak separation~$Δ$ of the gamma-ray pulsations and the radio lag~$δ$ between the gamma-ray and radio pulses. We selected several radio-loud millisecond gamma-ray pulsars with period~$P$ in the range 2-6~ms and showing a double peak in their gamma-ray profiles. We attempted to constrain the geometry of their magnetosphere, namely the magnetic axis and line-of-sight inclination angles for each of these systems. We applied a force-free dipole magnetosphere from the stellar surface up to the striped wind region -- well outside the light cylinder -- to fit the observed pulse profiles in gamma-rays, consistently with their phase alignment with the radio profile. In deciding whether a fitted curve is reasonable or not, we employed a least-square method to compare the observed gamma-ray intensity with that found from our model, emphasising the amplitude of the gamma-ray peaks, their separation, and the phase lag between radio and gamma-ray peaks. We obtained the best fits and reasonable parameters in agreement with observations for ten millisecond pulsars. Eventually, we constrained the geometry of each pulsar described by the magnetic inclination~$α$ and the light-of-sight inclination~$ζ$. We found that both angles are larger than approximately~$45^{\rm o}$.
