Shenzhen University School of Mathematical Sciences  

Liyuan Scholars Colloquium Session 154  

Lecture Title: The Bondi Energy-Momentum for the Einstein Scalar Fields  

Speaker: Researcher Zhang Xiao (Academy of Mathematics and Systems Science, Chinese Academy of Sciences)  

Time: 16:00–17:00, November 28, 2025 (Friday)  

Location: Classroom 1, Huixing Building, Yuehai Campus, Shenzhen University  

Abstract:  

Inspired by the interaction of gravitational waves and dark matter, we study the Bondi-Sachs metrics for Einstein massless scalar fields with zero cosmological constant. We provide asymptotic expansions for the Bondi-Sachs metrics as well as the scalar fields and prove the positivity of the Bondi energy-momentum under the condition  c = d = 0  at some retarded time  u_0 . This condition ensures that asymptotically null hypersurfaces near  u = u_0  are asymptotically null initial data sets of order 2, allowing the positive energy theorem for null infinity to be applied. The talk is based on joint work with Jialue Li.  

Speaker Profile:  

Zhang Xiao is a Researcher and Doctoral Supervisor at the Institute of Mathematics, Academy of Mathematics and Systems Science, Chinese Academy of Sciences. He has been awarded the National Science Fund for Distinguished Young Scholars, selected for the Chinese Academy of Sciences' "Hundred Talents Program," recognized as a national candidate for the "New Century Hundred-Thousand-Ten Thousand Talents Project," and is an expert receiving special government allowances from the State Council. He also holds the titles of Guangxi Zhuang Autonomous Region "Bagui Scholar" and Guangxi University "Junwu Scholar." His research focuses on differential geometry and mathematical physics, where he has made systematic contributions to the positive energy problem in general relativity and the noncommutative geometric theory of quantum gravity.  

All faculty and students are welcome!  

School of Mathematical Sciences  

November 26, 2025