郭硕鸿讲座二十（11月5日10：00-12：00）

主持人：张宏浩教授

报告简介：Gravitational waves are perturbations of the metric of space-time. Six polarizations are possible, although general relativity predicts that only two such polarizations, tensor plus and tensor cross are present for gravitational waves. The detection of extra polarization states is the smoking gun for the modification of general relativity in strong and nonlinear regime. In this talk, we discuss the antenna response to all the six polarizations and derive the analytical formulas which are valid for any equal-arm interferometric gravitational-wave detectors without optical cavities in the arms. We find that the response function averaged over the source direction and polarization angle decreases at high frequencies which deteriorates the signal-to-noise ratio registered in the detector. Space-based gravitational wave detectors cannot keep rigid structures and precise arm length equality, so the precise equality of detector arms which is required in a ground-based interferometer to cancel the overwhelming laser noise is impossible. The time-delay interferometry method is applied to unequal arm lengths to cancel the laser frequency noise. We give analytical formulas of the averaged response functions for tensor, vector, breathing and longitudinal polarizations in different TDI combinations, and obtain their asymptotic behaviors. We also use LISA and TianQin as examples to show sensitivity curves for all six possible polarizations.

报告人简介：龚云贵，华中科技大学二级教授、博士生导师，美国贝勒大学客座教授。国际广义相对论和引力学会终身会员，亚太物理学会天体物理、引力和宇宙学分会执委，中国引力与相对论天体物理学会秘书长。1991年毕业于华中理工大学（现华中科技大学）并获得学士学位，1994年在中国科学院理论物理研究所获得硕士学位，2001年获得美国德克萨斯州立大学奥斯汀分校博士,师从SU(3)理论创始者之一、美国科学院院士Neeman教授。在PRL等国际高水平学术期刊上发表了100多篇SCI学术论文，发表的学术论文在高能数据库InSpires中被引用4500余次，其中12篇论文被引用超过100次，h指数为35，入选了全球前10万科学家。主持了包括国家自然科学基金重点项目在内的多项国家及省部级科研项目。先后荣获教育部新世纪优秀人才计划、中国侨界双百贡献奖（创新人才奖）、重庆市自然科学一等奖等奖项及荣誉称号。现主要从事相对论引力与宇宙学的研究工作。