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arXiv 0903.3023astro-ph.HEastro-ph.GA
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揭示相干脉冲星射电辐射的本质

Unraveling the nature of coherent pulsar radio emission

Dipanjan Mitra, Janusz Gil, George I. Melikidze

摘要:

自发现射电星以来已经过去了40年,但其相干射电发射的物理机制仍然是一个谜。最近的观测和理论研究表明,脉冲星磁层辐射主要由垂直于脉冲星偶极磁场平面偏振的非常波组成。然而,这些波是由脉塞还是相干曲率辐射激发的根本问题仍然没有解决。需要高质量的单脉冲偏振测量来区分这两种可能的机制。在这里,我们展示了这样的{ \it decisive}强单脉冲从10个天文观测与GMRT,显示出极高的线性偏振与位置角以下的本地平均位置角遍历。这些脉冲相对没有去偏振,必须由唯一的单一偏振模式组成。我们把这种模式与相干曲率辐射激发的非寻常波联系起来。这一关键的观测特征使我们能够第一次支持相干曲率发射机制,而不包括脉泽机制。

英文摘要:

Forty years have passed since the discovery of pulsars, yet the physical mechanism of their coherent radio emission is a mystery. Recent observational and theoretical studies strongly suggest that the radiation outcoming from the pulsar magnetosphere consists mainly of extraordinary waves polarized perpendicular to the planes of pulsar dipolar magnetic field. However, the fundamental question whether these waves are excited by maser or coherent curvature radiation, remains open. High quality single pulse polarimetry is required to distinguish between these two possible mechanisms. Here we showcase such {\it decisive} strong single pulses from 10 pulsars observed with the GMRT, showing extremely high linear polarization with the position angle following locally the mean position angle traverse. These pulses, which are relatively free from depolarization, must consist of exclusively single polarization mode. We associate this mode with the extraordinary wave excited by the coherent curvature radiation. This crucial observational signature enables us to argue, for the first time, in favor of the coherent curvature emission mechanism, excluding the maser mechanism.

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