Parkes observations for project P934 semester 2016OCTS_BPSR_04

On the smallest scales, the warm interstellar medium contains surprisingly complex structure, including extremely overdense filaments and blobs of plasma that remain intact for months, despite physical processes that should cause them to disperse on short (week) time scales. It is possible that magnetization plays a role in confining this plasma. On these AU length scales the plasma is best probed by observing the scintillations of compact background radio sources such as pulsars and quasars. Recent observations show that overdensities are confined to narrow regions along lines of sight. Over the last decade, improvements in the analysis of scintillation have enabled better characterization of these structures. These studies however have focused on the ISM in the solar-system neighbourhood and the Galactic plane. Here we propose to observe pulsars at high galactic latitudes to extend the sample lines of sight. We will determine if the scattering regions are confined to the Galactic plane or persist into the halo of the galaxy. We will also search for (or place limits on) magnetic field variations within these scattering regions and discrete structures. Our observations will also provide important constraints on the scintillation of fast radio bursts, extragalactic sources which may be magnified by the similar structures to those studied here.

在最小尺度下，温暖星际介质（interstellar medium, ISM）蕴含着超乎预期的复杂结构，其中包含密度极高的等离子体纤维与团块。尽管存在应使其在短至数周的时间尺度内弥散的物理过程，这些结构却能保持完整达数月之久。磁化作用或许在约束这类等离子体的过程中扮演了关键角色。
在天文单位（AU）尺度下，探测这类等离子体的最优手段是观测脉冲星、类星体等致密背景射电源的射电闪烁现象。
近期的观测结果表明，高密度结构仅局限于视线方向上的狭窄区域。在过去十年间，射电闪烁分析技术的迭代升级使得对这类结构的表征精度大幅提升。
然而，此前的相关研究均聚焦于太阳系邻近区域与银道面内的星际介质。
本研究计划对高银纬脉冲星开展观测，以拓展视线方向的样本覆盖范围。我们将借此判定：散射区域究竟是仅局限于银道面，还是会延伸至星系银晕之中。
此外，我们还将搜寻这些散射区域与离散结构内的磁场变化（或给出其约束上限）。本次观测还将为快速射电暴的射电闪烁现象提供重要约束——快速射电暴作为一类河外射电源，其辐射或许会被与本研究探讨的结构相似的天体所放大。