arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1903.01694astro-ph.HE
收藏

用更真实的脉冲星磁层模拟gamma-ray光变曲线

Modeling gamma-ray light curves with more realistic pulsar magnetospheres

Gang Cao, Xiongbang Yang

摘要:

我们研究了耗散脉冲星磁层中的γ射线辐射模式和光变曲线。我们用几何方法和粒子轨道方法产生γ光变曲线。对于几何方法,假设γ射线发射起源于沿最后闭合线的有限宽度层,我们生成的γ射线光变曲线的基础上的均匀发射率沿磁场线的共动框架(CF)。对于粒子轨道法,我们考虑的电导率$σ$的空间分布,假设一个非常高的电导率内的轻圆柱和有限的电导率外的轻圆柱(LC)。假设所有的$γ$射线发射起源于外磁层外的LC,我们产生的伽马射线光变曲线计算现实的粒子轨迹和洛伦兹因子,同时考虑加速电场和曲率辐射损失。此外,我们比较了船帆座脉冲星在$>0.1\, \rm GeV$能量下的光变曲线。结果表明,磁层$σ$值较低的区域更适合于几何方法。然而,磁层内的LC和一个高的$σ$值外的LC的近无力制度是更有利于粒子轨道方法。注意,粒子轨迹方法使用与磁层的磁场自洽的平行电场。我们认为,从粒子轨道法的结果更支持的物理基础。

英文摘要:

We study the gamma-ray emission patterns and light curves in dissipative pulsar magnetospheres. We produce the gamma-ray light curves by using the geometric method and the particle trajectory method. For the geometric method, assuming the gamma-ray emission originates in a finite-width layer along the last closed lines, we generate the gamma-ray light curves based on the uniform emissivity along the magnetic field lines in the comoving frame (CF). For the particle trajectory method, we consider the spatial distribution of conductivity $σ$ by assuming a very high conductivity within the light cylinder and a finite conductivity outside the light cylinder (LC). Assuming that all the $γ$-ray emission originates in the outer magnetosphere outside the LC, we generate the gamma-ray light curves by computing realistic particle trajectories and Lorentz factors, taking into account both the accelerating electric field and curvature radiation loss. Further, we compare the modeling light curves to the observed light curves at $>0.1\, \rm GeV$ energies for Vela pulsar. Our results show that the magnetosphere with the low $σ$ value is more preferred for the geometric method. However, the magnetosphere with a near force-free regime within the LC and a high $σ$ value outside the LC is more favored for the particle trajectory method. It is noted that the particle trajectory method uses the parallel electric fields that are self-consistent with the magnetic fields of the magnetosphere. We suggest that the results from the particle trajectory method are more supported on the physical ground.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑