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arXiv 2303.04054astro-ph.HE
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从三维动力学全球磁层模型看伽马射线脉冲星现象学

The Gamma-Ray Pulsar Phenomenology in View of 3D Kinetic Global Magnetosphere Models

Constantinos Kalapotharakos, Zorawar Wadiasingh, Alice K. Harding, Demosthenes Kazanas

AI总结:

本文开发了具有磁场线依赖性等离子体注入的三维动力学脉冲星磁层模型,揭示了分离线区粒子注入对伽马射线发射的关键调节作用,并成功再现了Fermi目录中的光变曲线特征与基本平面关系。

摘要:

我们开发了具有依赖磁场线等离子体注入的脉冲星磁层动力学等离子体模型,揭示了各种磁层区域在调节伽马射线发射中的重要性。我们为所谓的开放区、闭合区和分离线区设定了不同的粒子注入率。开放区和闭合区中适度的粒子注入率确保了接近无力场的全球场结构,而耗散主要发生在赤道电流片及其周围。在分离线区注入的粒子会影响进入赤道电流片区域的粒子种群,从而影响相应的加速电场、粒子能量、谱截止能和伽马射线效率。分离线区模型重现了最近发现的伽马射线脉冲星基本平面(与曲率辐射发射一致)、伽马射线光变曲线形状,以及Fermi第二脉冲星目录中报告的射电滞后与峰间距的相关性。模型射束因子表明,Fermi目录中列出的脉冲星总伽马射线光度高估了实际光度。我们发现,对于小于$10^{34}$ erg/s的自转减率,辐射反应限制区制开始不再主导高能发射。我们的结果还表明,随着磁倾角增大,旋转赤道附近的“Y点”向光柱内部明显迁移,在伽马射线脉冲轮廓中激发出额外的峰。我们发现,在Y点之外等效的增强粒子注入会强化这些特征,使得模型伽马射线光变曲线与观测到的不一致。

英文摘要:

We develop kinetic plasma models of pulsar magnetospheres with magnetic-field-line-dependent plasma injection that reveal the importance of various magnetosphere regions in regulating the gamma-ray emission. We set different particle injection rates for the so-called open, closed, and separatrix zones. Moderate particle injection rates in open and closed zones ensure a global field structure close to the force-free one, while the dissipation occurs mainly in and around the equatorial current sheet. The particles injected in the separatrix zone affect the particle populations that enter the equatorial current sheet region and, therefore, the corresponding accelerating electric fields, particle energies, the spectral cutoff energy, and gamma-ray efficiency. The separatrix zone models reproduce the recently discovered fundamental plane of gamma-ray pulsars consistent with curvature radiation emission, the gamma-ray light-curve shapes, and the radio-lag vs. peak-separation correlation reported in the Fermi second pulsar catalog. The model beaming factors indicate that the pulsar total gamma-ray luminosities listed in the Fermi catalogs are overestimations of the actual ones. We find that the radiation reaction limited regime starts ceasing to govern the high-energy emission for spin-down powers less than $10^{34}$ erg/s. Our results also indicate that toward high magnetic inclination angles, the "Y point" around the rotational equator migrates well inside the light cylinder sparking additional peaks in the gamma-ray pulse profiles. We find that an equivalent enhanced particle injection beyond the Y point strengthens these features making the model gamma-ray light curves inconsistent with those observed.

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