RUI: The Universe at Redshifts 1-1000

现在在宇宙中可见的星系和星系团是在非常早期密度的小扰动中成长起来的，对应于红移1000。这一进化过程的许多细节尚不清楚。特别是，我们对原始等离子体重组后的前50亿年宇宙结构的形成只有初步（但正在迅速改进）的了解，即在红移1-1000的大范围内。对宇宙微波背景辐射（CBR）中各种波动的精确无线电波长搜索将告诉我们更多关于结构形成的早期阶段，在这个关键红移区间的高端。对z = 1-3的星系或星系碎片的光学、红外和无线电观测已经为星系形成的最后阶段（例如，恒星形成的开始）提供了重要的线索。对CBR波动的搜索和对高红移星系的无线电波长观测将会进行。这项研究的目标是帮助我们弥合对红移(z) = 1-1000对应时期宇宙演化的理解差距。将对哈勃深场进行无线电波长的研究。哈勃深空（HDF）是天文学家选择的一个小而典型的天空区域，用于所有波长的深入研究，从去年年底的一次非常深的太空望远镜曝光开始。目的是通过电磁波谱的观测来推动我们对星系演化的理解。我们的射电观测将在8.4 GHz和1.4 GHz的甚大阵列上进行，角分辨率从10英寸到0.4英寸（接近太空望远镜的分辨率）。我们观测的科学目标包括：测量射电光谱和形态，以确定射电发射的性质(超新星活动的同步辐射？活动星系核？)——改进低通量密度下射电源的计数——检查射电和光学亮度的相关性——改进CBR在角尺度6“-80”上的波动限制——寻找星系团或原星系团在z 1产生的微波信号。几个相关的项目将与这些努力并行，包括进一步研究干扰CBR波动搜索的前景噪声源，计划一个欧洲空间任务来绘制CBR，以及对VLA已经观测到的高红移星系和2-4微米宇宙微波背景的近红外观测。博士后助理将协助部分或全部这些项目。然而，该职位旨在为博士后提供进一步的教学和研究经验和培训。除了他或她的研究参与，博士后每年将在哈弗福德设计和教授一门课程，在我们部门成员的密切监督和指导下。本科生将参与研究的各个方面。

ABSTRACT Partridge The galaxies and clusters now visible in the Universe grew from small perturbations in density present at very early times, corresponding to redshifts 1000. Many details of this evolutionary process are poorly understood. In particular, we have only rudimentary (but rapidly improving) understanding of the formation of cosmic structure in the first 5 billion years after the recombination of the primeval plasma, that is in the large range of redshifts 1-1000. Refined radio-wavelength searches for various classes of fluctuations in the cosmic microwave background radiation (CBR) will tell us more about the early phases of structure formation, at the high end of this crucial redshift interval. Optical, IR and radio observations of galaxies or galaxy fragments at z = 1-3 are already providing important clues to the final stages of galaxy formation (e.g., the onset of star formation). Searches for CBR fluctuations and radio wavelength observations of high redshift galaxies will be carried out. The goal of the research is to help bridge the gap in our understanding of cosmic evolution during the epoch corresponding to redshifts (z) = 1-1000. A study of the Hubble Deep Field at radio wavelengths will be carried out. The Hubble Deep Field (HDF) is a small but typical region of the sky selected by astronomers for intensive study at all wavelengths, beginning with a very deep Space Telescope exposure late last year. The aim is to use observations across the electromagnetic spectrum to move our understanding of galaxy evolution forward. Our radio observations will be carried out at the Very Large Array at 8.4 and 1.4 GHz and with angular resolution from 10" down to 0.4" (close to the Space Telescope resolution). Among the scientific goals of our observations are: --measuring radio spectra and morphologies to determine the nature of the radio emission (synchrotron from supernova activity? active galactic nuclei?) --refining counts of radio source s at low flux densities --examining the correlation of radio and optical luminosities --improving limits on fluctuations in the CBR on angular scales 6"-80" --searching for the microwave signals produced by clusters or protoclusters of galaxies at z 1. Several related projects will parallel these efforts, including further work on foreground sources of noise which interfere with searches for CBR fluctuations, planning for a European space mission to map the CBR, and near infrared observations of both high redshift galaxies already observed at the VLA and of the 2-4 micron cosmic microwave background. A postdoctoral associate will assist in some or all of these projects. The position is intended, however, to provide the postdoc with further experience and training in both teaching and research. In addition to his or her research involvement, the postdoc would design and teach one course per year at Haverford, under the close supervision and mentoring of members of our department. Undergraduate students will be involved in various aspects of the research.