RUI: Radio Astronomical Investigations of the Interstellar Medium, Relativistic Gravitation, and Pulsars

在这里，魏斯伯格博士将开展一个包含三个主要主题的射电天文研究项目。前两个使用脉冲星作为研究其他物理现象的工具--即星际介质和相对论引力。第三个重点是研究脉冲星本身的发射和演化。脉冲星具有几个独特的性质，使它们成为星际介质的理想探测器。具体地说，它们的发射是脉冲的、极化的和点状的。它们的脉冲允许测量色散延迟，这导致了星际电子密度的确定。它们的高极化使得可以测量法拉第旋转，从而产生沿视线的银河系磁场测量。它们是点状的，这确保了信号沿着视线探测到一根针细的柱子。在该项目的这一部分，将进行五项主要的光谱和偏振研究，利用这三种性质来促进对星际介质中各种现象的理解，包括中性原子、分子和电离区的特征，特别是在最小尺度上。第一双星脉冲星PSR B1913+16已被证明是研究相对论引力的杰出实验室。虽然现在探测重力波发射的精度受到系统效应的限制，但仍有一些新的和有趣的相对论现象将在这里进行研究。“夏皮罗”引力传播延迟预计将在未来十年内变得可测量，这将导致两个额外的相对论测试，这可能会约束其他可行的引力理论。“大地线”自旋轴的进动使视线慢慢地漂移穿过脉冲星，从而允许罕见地在与其通常呈现的方向垂直的方向上瞥见发射光束。这里支持的额外观测将独特地有助于进一步限制束流形状，这是一个对发射机制研究有用的基本量。在发现这些天体40年后，脉冲星发射机制和脉冲星内部性质的细节仍然不清楚。魏斯伯格博士和学生们将进行一系列实验，以测量它们的偏振发射，目的是建立光束几何结构，并研究和创建经验发射模型。这些观测将使用阿雷西博、绿岸和帕克斯望远镜进行。卡尔顿学院的本科生将完整地参与数据采集和分析的所有方面，包括参加为期两个月的澳大利亚望远镜国家设施之旅。

Here, Dr. Weisberg will undertake a radioastronomical research program encompassing three major themes. The first two use pulsars as tools for the study of other physical phenomena - namely the interstellar medium and relativistic gravitation. The third focuses on studying the emissions and evolution of pulsars themselves.Pulsars possess several unique properties that make them ideal probes of the interstellar medium. Specifically, their emissions are pulsed, polarized, and pointlike. Their pulsing allows for dispersion delays to be measured, which leads to interstellar electron density determinations. Their high polarization permits the measurement of Faraday rotation, which yields galactic magnetic field measurements along the line of sight. That they are pointlike ensures that the signal probes a needle-thin column along the line of sight. In this part of the project, five principal spectrometric and polarimetric investigations will be undertaken that take advantage of these three properties to advance the understanding of a wide variety of phenomena in the interstellar medium, including the characteristics of neutral atomic, molecular, and ionized regions, especially on the smallest scales The first binary pulsar, PSR B1913+16, has proved to be an outstanding laboratory for the study of relativistic gravitation. Although the accuracy of probing gravity wave emission is now limited by systematic effects, there are still new and interesting relativistic phenomena that will be studied here. The 'Shapiro' gravitational propagation delay is expected to become measurable over the next decade, which will lead to two additional relativistic tests which can constrain otherwise viable gravitational theories. The 'geodetic' spin axis precession causes the line of sight to slowly drift across the pulsar, thereby permitting a rare glimpse of the emission beam in the direction orthogonal to its usual presentation. The additional observations which are supported here will uniquely help to further constrain the beam shape, a basic quantity that will be useful for emission mechanism studies. The details of the pulsar emission mechanism and of the nature of pulsar interiors are still unclear forty years after the discovery of these objects. A series of experiments to measure their polarized emissions will be carried out by Dr. Weisberg and students with an eye toward establishing the beam geometry, and studying and creating empirical emission models. The observations will be carried out with the Arecibo, Green Bank, and Parkes telescopes. Carleton College undergraduate students will be integrally involved in all aspects of data acquisition and analysis, including participation in two month-long trips to the Australia Telescope National Facility.