RUI: Pulsars and the Interstellar Medium

星际介质中的湍流提供了防止气体坍缩成煎饼所需的支撑。脉冲星观测的证据表明，能量的湍流级联可能存在超过12个数量级的尺度，从10到8（1亿）厘米到100秒差距。尽管大质量恒星可能通过恒星风、电离和超新星爆炸为级联提供了大部分能量，但这种湍流级联还没有被很好地理解。特别是，湍流能量在小于10的十分之一（100亿）厘米的尺度上耗散成热是必然发生的，但是发生这种情况的机制和物理条件的细节是粗略的。研究的目的是在10到10厘米及更小的尺度上确定湍流叶栅的强度，并进一步了解其耗散机制。所采用的主要技术将是在弱散射状态下对射电脉冲星闪烁的观测研究。升级后的波多黎各阿雷西博望远镜和即将完工的格林班克望远镜将为1 GHz以上的脉冲星观测提供绝佳的机会，这是开展此类研究的好时机。这是可以有效研究弱散射现象的频率范围。图像分裂现象，即脉冲星图像在强散射和弱散射之间的过渡状态下由于散射而分裂成两个或多个不同的碎片，也将被探索。目标是相同的：更好地阐明银河系中电子不均匀谱的强度，并寻求耗散尺度的证据。对明亮脉冲星的高时间分辨率研究也将使用著名的VLBI记录系统S2系统来获取基带采样数据。这些观测可以同时在几个观测站（和观测频率）进行，将允许对脉冲星色散测量进行高精度监测。这为银河系中电子的不均匀性提供了额外的信息。作为第二项工作，基带采样数据也将被分析，以研究脉冲星的短暂和强烈的射电发射，以便更好地了解发射物理。奥柏林学院的本科生将集中参与所有这些项目，并参与观察、分析和展示结果。

Abstract Stinebring Turbulence in the interstellar medium provides the support needed to keep the gas from collapsing into a pancake. Evidence from pulsar observations indicates that a turbulent cascade of energy may exist over 12 orders of magnitude in scale size from 10 to the eighth (one hundred million) cm to 100 parsec. This turbulent cascade is not well understood, although high mass stars probably account for much of the energy input to the cascade through stellar winds, ionization, and supernova explosions. In particular, the dissipation of turbulent energy into heat at some scale size less than 10 to the tenth (ten billion) cm must occur, but the details of the mechanism and the physical conditions under which this happens are sketchy. The research to be carried out is aimed at determining the strength of the turbulent cascade at a size scale around 10 to the tenth cm and smaller and to learn more about the dissipation mechanism. The main technique employed will be the observational study of radio pulsar scintillation in the weak scattering regime. This is an opportune time to embark on such a study since both the upgraded Arecibo, Puerto Rico telescope and the soon-to-be-completed Green Bank Telescope will provide outstanding opportunities for pulsar observations above 1 GHz. This is the frequency range in which weak scattering phenomena can be studied effectively. The phenomenon of image-splitting, in which the pulsar image separates into two or more distinct pieces due to scattering in the transition regime between strong and weak scattering, will also be explored. The goals are the same: to better elucidate the strength of the electron inhomogeneity spectrum in the Galaxy and to seek evidence for a dissipation scale. High time resolution studies of bright pulsars will also be undertaken using a well-known VLBI recording system, the S2 system, to obtain baseband sampled data. These observations, which can be conducted at several observat ories (and observing frequencies) simultaneously, will allow high-precision monitoring of pulsar dispersion measures. This provides additional information about the electron inhomogeneities in the Galaxy. As a secondary effort, the baseband sampled data will also be analyzed to study brief and intense radio emission from pulsars in order to better understand the emission physics. Undergraduate students from Oberlin College will be centrally involved in all of these projects and will participate in observations, analysis, and the presentation of the results.