脉冲星极盖处的回流电场屏蔽
Electric Field Screening with Back-Flow at Pulsar Polar Cap
摘要：
最近的$γ$射线观测表明，粒子加速发生在脉冲星磁层的外部区域。外加速区（OAR）的磁场线与中子星表面（NSS）相连。如果在NSS附近产生大量的电子-正电子对，这些电子对就会流入OAR并屏蔽那里的电场。为了激活OAR，应该抑制由于NSS附近的电场引起的电磁级联。然而，由于预期沿着穿过OAR的场线有返回电流，因此单独从NSS提取的流出不能屏蔽NSS正上方的电场。在本文中，我们分析和数值研究的电场屏蔽在NSS考虑回流粒子的影响，从OAR。在某些有限的情况下，如果只有超相对论粒子（$γ\gg1$）流回NSS，则电场被屏蔽而没有显著的对级联。另一方面，如果电子-正电子对具有显著的数密度和温和的相对论温度，预计分布在磁层的广泛区域，流回NSS，这些粒子调整电流和电荷密度，因此电场可以被屏蔽而没有对级联。我们得到了粒子数密度屏蔽电场的条件。我们还发现，在从NSS离子提取的情况下，粒子束被喷射到外部区域的准周期性，这是一个可能的机制，观察到的无线电发射。
英文摘要：
Recent $γ$-ray observations suggest that the particle acceleration occurs at the outer region of the pulsar magnetosphere. The magnetic field lines in the outer acceleration region (OAR) are connected to the neutron star surface (NSS). If copious electron--positron pairs are produced near the NSS, such pairs flow into the OAR and screen the electric field there. To activate the OAR, the electromagnetic cascade due to the electric field near the NSS should be suppressed. However, since a return current is expected along the field lines through the OAR, the outflow extracted from the NSS alone cannot screen the electric field just above the NSS. In this paper, we analytically and numerically study the electric-field screening at the NSS taking into account the effects of the back-flowing particles from the OAR. In certain limited cases, the electric field is screened without significant pair cascade if only ultrarelativistic particles ($γ\gg1$) flow back to the NSS. On the other hand, if electron--positron pairs with a significant number density and mildly relativistic temperature, expected to distribute in a wide region of the magnetosphere, flow back to the NSS, these particles adjust the current and charge densities, so that the electric field can be screened without pair cascade. We obtain the condition for the number density of particles to screen the electric field at the NSS. We also find that in ion-extracted case from the NSS, bunches of particles are ejected to the outer region quasi-periodically, which is a possible mechanism of observed radio emission.
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。
