On the gauge dependence of scalar induced secondary gravitational waves during radiation and matter domination eras  

作　　者：Arshad Ali Ya-Peng Hu Mudassar Sabir Taotao Sui 

机构地区：[1]College of Physics,Nanjing University of Aeronautics and Astronautics,Nanjing 211106,China [2]Key Laboratory of Aerospace Information Materials and Physics(NUAA),MIIT,Nanjing 211106,China [3]Center for Gravitation and Cosmology,College of Physical Science and Technology,Yangzhou University,Yangzhou 225009,China [4]School of Geophysics and Geomatics,China University of Geosciences,Wuhan 430074,China

出　　处：《Science China(Physics,Mechanics & Astronomy)》2023年第9期23-41,共19页中国科学：物理学、力学、天文学（英文版）

基　　金：supported by the National Natural Science Foundation of China (Grant Nos. 12175105, 12147175, 12247170, 11575083, and 11565017);the Top-notch Academic Programs Project of Jiangsu Higher Education Institutions (TAPP)。

摘　　要：We revisit the vital issue of gauge dependence in the scalar-induced secondary gravitational waves(SIGWs), focusing on the radiation domination(RD) and matter domination(MD) eras. The energy density spectrum is the main physical observable in such induced gravitational waves. For various gauge choices, there has been a divergence in the energy density, ?GW, of SIGWs.We calculate SIGWs in diferent gauges to quantify this divergence to address the gauge-dependent problem. In our previous studies, we had found that the energy density diverges in the polynomial power of conformal time(e.g., η^(6) in uniform density gauge). We try to fix this discrepancy by adding a counter-term that removes the fictitious terms in secondary tensor perturbations. We graphically compare the calculations in various gauges and also comment on the physical origin of the observed gauge dependence.

关 键 词：scalar induced gravitational waves gauge transformation COSMOLOGY 

分 类 号：P142.84[天文地球—天体物理]