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Galactic interstellar scintillation observed from four globular cluster pulsars by FAST

中国科学:物理学、力学、天文学英文版 2023年第9期66卷 119-127页

作者： Dandan Zhang zhenzhao tao Mao Yuan Jumei Yao Pei Wang Qijun Zhi Weiwei Zhu Xun Shi Michael Kramer Di Li Lei Zhang Guangxing Li School of Mathematical Sciences School of Physics and Electronic SciencesGuizhou Normal UniversityGuiyang 550001China National Astronomical Observatories Chinese Academy of SciencesBeijing 100012China Guizhou Provincial Key Laboratory of Radio Astronomy and Data Processing Guiyang 550001China Department of Astronomy Beijing Normal UniversityBeijing 100875China Xinjiang Astronomical Observatory Chinese Academy of SciencesUrumqi 830011China South-Western Institute for Astronomy Research(SWIFAR) Yunnan UniversityKunming 650000China Institute for Frontiers in Astronomy and Astrophysics Beijing Normal UniversityBeijing 102206China Max-Planck Institut fr Radioastronomie Bonn D-53121Germany Key Laboratory of Radio Astronomy and Technology Chinese Academy of SciencesBeijing 100101China Computational Astronomy Platform Zhejiang LabHangzhou 311121China

We report detections of scintillation arcs for pulsars in globular clusters M5,M13 and M15 for the first time using the Fivehundred-meter Aperture Spherical radio Telescope(FAST).From observations of these arcs at multiple epochs,we infer that screen-like scattering medium exists at distances 4.1_(-0.3)^(+0.2),6.7_(-0.2)^(+0.2)and 1.3_(-1.0)^(+0.7) kpc from Earth in the directions of M5,M13 and M15,respectively.This means M5's and M13's scattering screens are located at 3.0_(-0.2)^(+0.1) and 4.4_(-0.1)^(+0.1) kpc above the galactic plane,whereas,M15's is at 0.6_(-0.5)^(+0.3) kpc below the plane.We estimate the scintillation timescale and decorrelation bandwidth for each pulsar at each epoch using the one-dimensional auto-correlation in frequency and time of the dynamic spectra.We found that the boundary of the Local Bubble may have caused the scattering of M15,and detected the most distant off-plane scattering screens to date through pulsar scintillation,which provides evidence for understanding the medium circulation in the Milky Way.

关键词： pulsars scintillation globular clusters

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Pulsar candidate selection using ensemble networks for FAST drift-scan survey

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Science China(Physics,Mechanics & Astronomy) 2019年第5期62卷 61-70页

作者： HongFeng Wang WeiWei Zhu Ping Guo Di Li SiBo Feng Qian Yin ChenChen Miao zhenzhao tao ZhiChen Pan Pei Wang Xin Zheng XiaoDan Deng ZhiJie Liu XiaoYao Xie XuHong Yu ShanPing You Hui Zhang FAST Collaboration Image Processing and Pattern Recognition Laboratory College of Information Science and TechnologyBeijing Normal UniversityBeijing 100875China CAS Key Laboratory of FAST Chinese Academy of SciencesBeijing 100101China School of Information Management Dezhou UniversityDezhou 253023China Image Processing and Pattern Recognition Laboratory School of Systems ScienceBeijing Normal UniversityBeijing 100875China University of Chinese Academy of Sciences Beijing 100049China Key Laboratory of Information and Computing Science Guizhou Province Guizhou Normal UniversityGuiyang 550001China School of Physics and Electronic Science Guizhou Normal UniversityGuiyang 550001China 不详

The Commensal Radio Astronomy Five-hundred-meter Aperture Spherical radio Telescope(FAST) Survey(CRAFTS) utilizes the novel drift-scan commensal survey mode of FAST and can generate billions of pulsar candidate signals. The human experts are not likely to thoroughly examine these signals, and various machine sorting methods are used to aid the classification of the FAST candidates. In this study, we propose a new ensemble classification system for pulsar candidates. This system denotes the further development of the pulsar image-based classification system(PICS), which was used in the Arecibo Telescope pulsar survey, and has been retrained and customized for the FAST drift-scan survey. In this study, we designed a residual network model comprising 15 layers to replace the convolutional neural networks(CNNs) in PICS. The results of this study demonstrate that the new model can sort >96% of real pulsars to belong the top 1% of all candidates and classify >1.6 million candidates per day using a dual-GPU and 24-core computer. This increased speed and efficiency can help to facilitate real-time or quasi-real-time processing of the pulsar-search data stream obtained from CRAFTS. In addition, we have published the labeled FAST data used in this study online, which can aid in the development of new deep learning techniques for performing pulsar searches.

关键词： pulsars neural networks data analysis

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地外文明技术印迹射电搜寻进展

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科学通报 2023年第5期68卷 440-447页

作者：张同杰陶振钊刘文斐李时雨赵海辰张志嵩李健康陈沂瑄栾晓航王洪丰张建臣北京师范大学天文与天体物理前沿科学研究所北京102206 北京师范大学天文系北京100875 德州学院天文科学研究院德州253023 齐鲁师范学院物理与电子工程系济南250200 北京天文馆北京100044 中国科学院国家天文台北京100012 云南大学天文系昆明650500 德州学院计算机与信息工程学院德州253023

基于哥白尼原理、德雷克公式以及大量系外行星的发现,大多科学家相信地球之外一定存在着生命尤其是高级智慧生命(或文明).射电技术由于其优势而成为地外文明搜寻的最佳手段之一.“中国天眼”(FAST)是全世界最大的单天线射电望远镜,地外... 详细信息

基于哥白尼原理、德雷克公式以及大量系外行星的发现,大多科学家相信地球之外一定存在着生命尤其是高级智慧生命(或文明).射电技术由于其优势而成为地外文明搜寻的最佳手段之一.“中国天眼”(FAST)是全世界最大的单天线射电望远镜,地外文明搜寻(search for extraterrestrial intelligence,SETI)是其五大科学目标之一,它在低频射电L波段上极高的灵敏度对SETI有着重要意义.基于FAST专门用于SETI观测的后端设备和正式申请的观测时间,我们开展了SETI后端共时巡天观测和系外行星目标观测.与加利福尼亚大学伯克利分校的在家地外文明搜寻(SETI@home)和突破聆听(Breakthrough Listen)团队合作,我们发展了SETI目标观测多波束匹配模式以及使地外文明(extraterrestrial intelligence,ETI)信号鉴别过程更加科学完备的偏振和频率漂移判据,实施了观测和数据处理来筛选ETI候选目标.本文主要介绍国际上的SETI观测历史,尤其是FAST进行SETI的研究现状和最新进展以及未来展望.

关键词：地外智慧生命搜寻技术印迹射频干扰共时巡天观测系外行星

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脉冲星衍射式闪烁观测研究进展

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北京师范大学学报（自然科学版） 2020年第1期56卷 22-29页

作者：陶振钊王培姚菊枚朱炜玮支启军董爱军贵州师范大学物理与电子科学学院贵州贵阳550025 中国科学院国家天文台北京100101 贵州师范大学贵州省射电天文数据处理重点实验室贵州贵阳550025

介绍脉冲星星际闪烁效应产生的机制,简要描述衍射式闪烁的观测研究方法,并总结了近些年衍射式闪烁观测研究的进展,主要包含使用闪烁效应限制星际介质电子密度涨落谱、估算脉冲星切向速度、分辨脉冲星射电辐射区尺度、获取脉冲星双星轨... 详细信息

介绍脉冲星星际闪烁效应产生的机制,简要描述衍射式闪烁的观测研究方法,并总结了近些年衍射式闪烁观测研究的进展,主要包含使用闪烁效应限制星际介质电子密度涨落谱、估算脉冲星切向速度、分辨脉冲星射电辐射区尺度、获取脉冲星双星轨道参数、搜索脉冲星的非脉冲射电辐射等,以及总结了国内一些射电望远镜对脉冲星闪烁观测研究工作及FAST观测预期.

关键词：脉冲星星际介质散射闪烁

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