摘要
引力波探测打开了探索天体物理和宇宙学中基本问题的新窗口.本文简要介绍了手征引力波背景的早期宇宙起源,面向空间引力波探测器LISA、太极和天琴等所对应的毫赫兹频段.本文对比了在宇宙早期辐射主导时期,类轴子-暗光子耦合和类轴子-引力子耦合两种模型中由类轴子场产生的手征引力波谱,并讨论了具有引力陈-西蒙斯耦合的轴子单场暴胀机制.数值计算了在不同模型下产生的引力波频谱形状及红移到今天的峰值频率范围,并讨论了由陈-西蒙斯拓扑项引起的引力波信号宇称破缺效应.
Abstract
The first detection of gravitational waves has opened a new window to probe fundamental problems in astrophysics and cosmology.In this paper,we briefly introduce the chiral gravitational waves originating from the early universe,focusing on those within the millihertz-frequency range.Millihertz frequencies are within the detection capabilities of space-based gravitational wave detectors,including LISA,Taiji,and Tianqin.We mainly compare the gravitational wave spectra generated by a rolling axion field during the radiation-dominated era,examining two similar models:axion-dark-photon coupling and axion-graviton coupling.Furthermore,we introduce a mechanism of axion inflation with gravitational Chern-Simons coupling.We numerically calculate the shape of the stochastic gravitational wave spectrum generated in this scenario,paying special attention to its peak frequency range as it would be observed today.Additionally,we discuss the parity-violating effect of the gravitational wave signal induced by the Chem-Simons topological term.
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