Serendipitous Science: Using Piggyback Techniques to Study the Galaxy

自1998年底以来，寻找地外智慧（SETI@home）项目一直在阿雷西博射电天文台记录以1420兆赫为中心的2.5兆赫波段的数据，该波段对中性氢气很敏感。这是在正常的天文观测中完成的，所以这种“背驮式”观测模式不需要专门的望远镜时间。现有的35tb数据集包括从阿雷西博观测到的几乎整个天空。天空的某些部分已经被观测了50次甚至更多。数据集继续以每天约50gb的速度增长。一种新的数据记录仪将于2003年投入使用，它将把记录的带宽扩大到100兆赫，并允许多波束观测模式。它将同时用于阿雷西博和澳大利亚的帕克斯天文台。这个项目将把这个庞大的数据集用于天文学目的。利用这些数据对星系中中性氢（HI）分布进行调查的工作已经开始，这被称为seti。该测量比现有的单碟测量具有更好的角度分辨率，比现有或计划中的干涉测量具有更好的灵敏度。另一个相对未开发的无线电参数空间领域是微秒时间尺度分散脉冲。PI Korpela和合作者将开发一个分布式计算应用程序（称为Astropulse）来检查这些持续时间的单脉冲和重复脉冲的数据集。对于单脉冲，这将是同类调查中最敏感的。通过这次调查，我们有可能探测到原始黑洞的辐射，至少，它将为这种黑洞的存在设定迄今为止最好的限制。这项调查还可以探测到来自未知脉冲星或亚毫秒脉冲星的巨大脉冲。更广泛的影响：这些项目以相对较低的成本为天文学界做出了贡献。由于数据是为其他目的而存在的，因此不存在检测的成本。为大规模数据集的分布式计算、存储和分析而开发的技术将对天文学界具有重要的价值。加州大学伯克利分校集团长期致力于教育和公众宣传。SETI@home项目已经大大提高了公众对科学的兴趣。成千上万的K-12教师在他们的科学课程中使用SETI@home， SETI@home是科学和数学大探索（GEMS）计划的一部分。由于HI调查和Astropulse被认为是SETI@home的延伸，这些项目为讨论银河系及其结构、黑洞甚至宇宙学提供了一个自然的途径。该项目的网站将成为教师学习和教授天文学这些方面的资源。研究生和本科生都参与了SETHI和Astropulse项目。Astropulse的主要分析代码是由一个研究生编写的。Astropulse的结果将构成博士论文的重要部分。

AST 0307956PI KorpelaSince late 1998, the Search for ExtraTerrestrial Intelligence (SETI@home) project has been recording data in a 2.5 MHz band centered at 1420 MHz, sensitive to neutral hydrogen gas, at the Arecibo radio observatory. This is done during normal astronomical observations, so this "piggyback" observing mode does not require dedicated telescope time. The existing 35 Terabyte dataset includes observations from nearly the entire sky visible from Arecibo. Some portions of the sky have been observed 50 or more times. The dataset continues to grow at a rate of about 50 Gigabytes per day. A new data recorder, coming on line in 2003, will expand the recorded bandwidth to 100 MHz and allow multibeam observation modes. It will be used at both Arecibo and the Parkes Observatory in Australia. This project will turn this vast dataset toward astronomical purposes. Work has begun on using this data to conduct a survey of the neutral hydrogen (HI) distribution in the galaxy, which has been dubbed SETHI . This survey has better angular resolution than existing single dish surveys, and better sensitivity than existing or planned interferometric surveys. Another relatively unexplored area of radio parameter space is that of microsecond time scale dispersed pulses. PI Korpela and collaborators will develop a distributed computing application (called Astropulse) to examine the dataset for both single and repeated pulses of these durations. For single pulses, this will be the most sensitive survey of its kind. With this survey there is the potential of detecting emission from primordial black holes and, at the very least, it will set the best limit to date on the existence of such black holes. This survey could also detect giant pulses from unknown pulsars or detect sub-millisecond pulsars. Broader Impacts: These projects bring contributions to the astronomical community at a relatively low cost. Since the data exist for other purposes, the cost of instrumentation is non-existent. The techniques developed for distributed computation and storage and analysis of vast datasets will be of significant value to the astronomical community. The University of California Berkeley group has a long standing commitment to education and public outreach. The SETI@home program has already vastly increased public interest in science in general. Thousands of K-12 teachers use SETI@home in their science curriculum and SETI@home is part of the Great Exploration in Science and Mathematics (GEMS) program. Because the HI survey and Astropulse are considered to be an extension of SETI@home, these projects allow a natural path into discussion of the Galaxy and its structure, black holes, and even cosmology. The project web site will be a resource for teachers to learn and to teach about these aspects of astronomy. Students at both the graduate and undergraduate level have been involved SETHI and Astropulse. The Astropulse primary analysis code is being written by a graduate student. The Astropulse results will form a significant portion of a Ph.D. thesis.