报告题目：       Chinese Pulsar Timing Array and Nanohertz Gravitational Waves

报告人：          胥恒 博士

报告人单位：  中国科学院国家天文台

报告语言：      中文

报告时间：      2023年8月17日(周四) 上午9:30-11:00

报告地点：      1号楼502会议室

报告摘要：

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Gravitational waves (GWs)—the space-time ripples, were predicted by Einstein’s general theory of relativity in 1916. It was until 2015 when GWs was directly detected by LIGO, thought their existence was first demonstrated in the 1970s and 1980s through the observations to a pulsar binary system. The GWs detected by LIGO were generated by compact stellar compact object binaries, thus the frequency is about 100 Hz, and the sources are mainly in the local Universe. However, the nanohertz GWs produced by supermassive black hole binaries in the center of galaxies, early Universe processes, cosmic strings, etc, have not been detected yet. These nanohertz GWs can provide crucial information about the supermassive black holes, the history of galaxy mergers, and the formation of large-scale structures in the Universe. Currently, the only known way to detect nanohertz GWs is pulsar timing array (PTA) —long term timing monitoring of a group of stably rotating millisecond pulsars using radio telescopes. Three regional PTA collaborations have made decades of efforts in this field, but no detection had been made until this year. The detection of nanohertz GWs holds great potential for advancing our understanding of the Universe.

In this talk, I will briefly introduce the historical studies on nanohertz GWs, and then talk about the recent results from the Chinese Pulsar Timing Array (CPTA) collaboration including the CPTA timing data collected using FAST and the searching the nanohertz stochastic gravitational wave background (GWB). I will also discuss the recent results of searching nanohertz GWB from the major regional PTAs, and the implications from these results.

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报告人简介：

Heng Xu is a postdoc at the National Astronomical Observatories of Chinese Academy of Sciences, he obtained the PhD degree from Peking University. Heng’s research interests are pulsar timing, gravitational wave and fast radio burst.

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云台邀请团组：射电天文与VLBI团组

邀请方联系人：徐永华  李志玄 郝龙飞     15887870718

8月15日