RUI: Radio Studies of the Interstellar Medium and Pulsars

Weisberg AST-9530710将进行星际介质和脉冲星的射电天文学研究。观测将在波多黎各的阿雷西博天文台、澳大利亚的帕克斯射电望远镜、西弗吉尼亚州的格林班克望远镜和新墨西哥州的甚大阵列上进行。特别是升级后的阿雷西博天文台望远镜和格林班克望远镜将成为高度灵敏的仪器，使人们能够进行比以前更灵敏的观测。星际介质的研究主要分为三大类：第一类是获得和测量遥远脉冲星的中性氢线吸收光谱，并根据这些光谱确定其运动距离。沿着脉冲星-地球视线线的电子密度将从距离和色散测量中得出，并将银河系电子分布模型与这些结果进行比较。在第二类中，将通过高纬度和附近脉冲星的中性氢线吸收测量和脉冲星方向的复合线观测来研究星际氢的空间结构和物理性质。第三类包括通过偏振脉冲星信号的法拉第旋转测量来研究银河系磁场。一个实验将研究时间和小尺度的空间变化，而另一个实验将研究磁场的广泛结构。本征脉冲星研究也有三个主要类别：第一，将测量和校准全斯托克斯参数脉冲星偏振剖面，并在这些和所有其他已发表的观测结果的基础上分配形态分类。其次，极化剖面将被检查的时间变化，可能表明自由进动或本征光束的变化，以及银河磁场的变化如上所述。第三，将通过经验/几何分析和旋转矢量模型与测量位置角度的拟合来研究发射光束的几何形状。卡尔顿学院的本科生将参与研究项目。

Weisberg AST-9530710 Radioastronomical studies of the interstellar medium and pulsars will be carried out. Observations will be conducted at the Arecibo Observatory in Puerto Rico, the Parkes radio telescope in Australia, the Green Bank Telescope in West Virginia, and the Very Large Array in New Mexico. In particular, the upgraded Arecibo Observatory telescope and the Green Bank Telescope will be highly sensitive instruments that will enable one to make much more sensitive observations than previously possible. The interstellar medium studies are divided into three main categories: In the first, neutral hydrogen line absorption spectra of distant pulsars will be obtained and measured and kinematic distances will be determined from these spectra. The electron densities along the pulsar-Earth lines of sight will then be derived from distances and dispersion measures, and models of the Galactic distribution of electrons will be compared with these results. In the second category, the spatial structure and physical properties of interstellar hydrogen will be studied with neutral hydrogen line absorption measurements of high- latitude and nearby pulsars and recombination line observations in the directions of pulsars. The third category consists of studies of the Galactic magnetic field through Faraday rotation measurements of polarized pulsar signals. Temporal and small- scale spatial variations will be studied in one experiment, while the broad structure of the magnetic field will be investigated in another. There are also three main categories of intrinsic pulsar investigations: First, full Stokes parameter pulsar polarization profiles will be measured and calibrated, and morphological classifications will be assigned on the basis of these and all other published observations. Second, polarized profiles will be examined for temporal variations that could indicate free precession or intrinsic beam changes as well as the Galactic magnetic field variations di scussed above. Third, the emission beam geometry will be studied via empirical/geometrical analyses and fits of the rotating vector model to measured position angles. Undergraduate students at Carleton College will be involved in the research program.