A new census of globular cluster pulsars

球状星团脉冲星的新普查

• 批准号: 0907967
• 负责人: Duncan Lorimer
• 金额: $ 26.8万
• 依托单位: West Virginia University Research Corporation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2012-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0907967&HistoricalAwards=false
• 关键词: new; census; globular; cluster; pulsars

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Dr. Duncan Lorimer and collaborators will undertake a detailed statistical study of the neutron star population in the globular clusters of the Milky Way Galaxy. The dense stellar environments provided by globular clusters act as astrophysical laboratories to probe stellar evolution and the dynamics of binary and multiple star systems. Neutron stars in globular clusters are long-lived tracers of the integrated star formation history in clusters and have a wealth of physical applications. Radio pulsars - rapidly spinning highly magnetized neutron stars - provide a very powerful window into this population. Timing observations of radio pulsars, for example, have demonstrated for the first time the existence of ionized gas in globular clusters and provide recent evidence for the existence of high-mass neutron stars which challenge many equations of state for super-dense matter. Future discoveries expected from globular clusters include binary pairs of millisecond pulsars and pulsar-black hole binary systems.Currently, 140 radio pulsars are known in 26 globular clusters. Around half of these discoveries have been made in the past five years by groups using the NSF-funded Green Bank Telescope in West Virginia. Despite these significant advances, the last major census of the radio pulsar population in globular clusters was carried out over 15 years ago when less than two-dozen objects were known in a handful of clusters. At that time, it was not clear whether the progenitor population of millisecond pulsars (the low-mass X-ray binaries) was sufficient to account for the estimated number of 10,000 pulsars suspected to exist in the Galactic globular cluster population. Dr. Lorimer plans a comprehensive new analysis of the population to take account of selection effects due to binary motion, interstellar propagation and radio frequency interference. His team has a broad range of experience in pulsar observations and population modeling necessary to develop detailed Monte Carlo models of the underlying population of radio pulsars in globular clusters.In addition to characterizing the overall size and birth-rate of radio pulsars in globular clusters, they will apply both frequentist and Bayesian statistical analyses to determine the underlying distributions of spin period, luminosity and (for binary systems) orbital parameters. They will also address the smaller subset of younger pulsars known to exist in globular clusters, and those binaries which will merge on sub-Hubble timescales due to the emission of gravitational radiation. These results are expected to provide vital input to complementary studies of the neutron star population which are based on models of stellar evolution. They will also help determine the likely size of the population of compact object binaries that contribute as gravitational-wave sources.The proposed research will impact upon a number of other areas which will benefit the state of West Virginia, teaching astronomy courses and astronomical research in general. Specifically, the PI and his team will (a) develop a freely-available laboratory component for undergraduate astronomy students; (b) develop an inquiry-based learning tool for high-school science teachers and their students; (c) raise the international research profile of West Virginia University and help to increase the number of students in Science, Technology, Engineering and Mathematics disciplines; (d) enhance the science case for future national and international radio facilities; (e) make available an open-source library of tools for Monte Carlo simulations of astronomical populations.

该奖项是根据2009年《美国回收与再投资法》（公共法第111-5）.DR资助的。邓肯·洛里默（Duncan Lorimer）和合作者将对银河系的球状簇中的中子星人口进行详细的统计研究。 球形簇提供的密集恒星环境充当天体实验室，以探测恒星进化以及二元和多个恒星系统的动力学。球状簇中的中子恒星是群集中综合恒星形成历史的长期示踪剂，并且具有大量的物理应用。无线电脉冲星 - 迅速旋转高度磁中子星 - 为该人群提供了一个非常强大的窗口。例如，无线电脉冲星的定时观察首次证明了球状簇中电离气体的存在，并提供了最新的证据，证明存在高质量中子恒星，这些恒星挑战了许多状态方程的超密集物质。球状簇预期的未来发现包括毫秒的二进制脉冲星和脉冲 - 黑孔二进制系统。当然，在26个球状簇中已知140个无线电脉冲星。在过去的五年中，使用NSF资助的绿色银行望远镜的小组在过去五年中大约有一半的发现。尽管取得了重大进展，但在15年前，在少数群集中知道了少于二分散的物体。当时，目前尚不清楚毫秒脉冲星的祖细胞种群（低质量X射线二进制二进制物）是否足以说明估计的10,000个脉冲星数量涉嫌在银河球体簇种群中存在。 Lorimer博士计划对人群进行全面的新分析，以考虑到由于二元运动，星际传播和射频干扰而引起的选择效果。 His team has a broad range of experience in pulsar observations and population modeling necessary to develop detailed Monte Carlo models of the underlying population of radio pulsars in globular clusters.In addition to characterizing the overall size and birth-rate of radio pulsars in globular clusters, they will apply both frequentist and Bayesian statistical analyses to determine the underlying distributions of spin period, luminosity and (for binary systems) orbital parameters.他们还将解决已知在球状簇中存在的年轻脉冲星的较小子集，以及由于引力辐射的发射，这些二进制文件将在亚与超边的时间尺度上合并。这些结果有望为基于恒星进化模型的中子星人群的互补研究提供重要的输入。他们还将帮助确定作为重力波源有助于的紧凑型物体二进制群体种群的可能大小。拟议的研究将影响许多其他将使西弗吉尼亚州受益的领域，教授天文学课程和一般的天文学研究。具体来说，PI和他的团队将（a）为本科生的学生开发一个自由利用的实验室组件； （b）为高中科学老师及其学生开发一种基于查询的学习工具； （c）提高西弗吉尼亚大学的国际研究知识，并有助于增加科学，技术，工程和数学学科中的学生人数； （d）加强未来国家和国际广播设施的科学案例； （e）为蒙特卡洛模拟天文数字提供开源工具库。