Seminar - Zhoujian Cao (Beijing Normal University)

Seminar time: 2021/11/09 10:00-11:30 (CST)

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Conference ID: 319 254 186

Speaker: Zhoujian Cao(Beijing Normal University)

Measurement of gravitational wave memory

Zhoujian Cao

Abstract

Gravitational wave (GW) memory is an important prediction of general relativity. Existing works on the GW memory detection focus on the waveform analysis. It is hard for waveform analysis method to detect the GW memory due to its quasi-direct current behavior and weakness. We implement a completely different scheme to estimate the GW memory. In this scheme, we firstly apply the Bondi-Metzner-Sachs method to calculate the GW memory of binary black hole based on numerical relativity simulation. Then we construct a surrogate model to relate binary black hole’s parameters and the GW memory. Afterwards we apply this surrogate model together with Bayesian techniques to estimate the GW memory of the 48 binary black hole events recorded in O1/O2/O3a. The GW memory corresponding to the all 48 events has been estimated. The most interesting results are for GW190814. The corresponding GW memory is about $-1\times10^{-23}$ and $1\times10^{-23}$ for Hanford detector and Livingston detector respectively. At the mean time we find with 3$\sigma$ C.L. that the memory strain of GW190814 is negative on Hanford detector while positive on Livingston detector.

Bio

Zhoujian Cao, Bachelor and Ph.D. from Beijing Normal University, was hired by the Academy of Mathematics and Systems Science, Chinese Academy of Sciences as an assistant researcher after receiving his Ph.D. in 2006, specializing in the study of gravitational wave astronomy, especially numerical relativity. He is the project leader of the “Numerical Relativity and Gravitational Wave Modeling” project of the National Natural Science Foundation of China’s gravitational wave major project and a key member of the innovative research group “gravitational wave astronomy”. Zhoujian Cao and his collaborators established and improved the numerical relativity calculation method Z4c. The Z4c algorithm has been used by many numerical relativity groups in the international numerical relativity community. Cao Zhoujian and the others have completed and developed China’s completely independent numerical relativity software, which provides a number of domestic counterparts with tools for numerical relativity research. They also established the precession-merger-ring-dang complete gravitational wave model SEOBNRE of the elliptical orbit double black hole merging system, and prepared an immediately usable gravitational wave template for the gravitational wave data processing of the elliptical orbit binary star system.