Prospects for improving cosmological parameter estimation with gravitational-wave standard sirens from Taiji  

太极计划的引力波标准汽笛观测将助力宇宙学参数测量

作　　者：Ze-Wei Zhao Ling-Feng Wang Jing-Fei Zhang Xin Zhang 赵泽伟;王凌风;张敬飞;张鑫(Department of Physics,College of Sciences,Northeastern University,Shenyang 110819,China;Ministry of Education's Key Laboratory of Data Analytics and Optimization for Smart Industry,Northeastern University,Shenyang 110819,China;Center for High Energy Physics,Peking University,Beijing 100080,China)

机构地区：[1]Department of Physics,College of Sciences,Northeastern University,Shenyang 110819,China [2]Ministry of Education's Key Laboratory of Data Analytics and Optimization for Smart Industry,Northeastern University,Shenyang 110819,China [3]Center for High Energy Physics,Peking University,Beijing 100080,China

出　　处：《Science Bulletin》2020年第16期1340-1348,M0003,共10页科学通报（英文版）

基　　金：the National Natural Science Foundation of China(11975072,11690021,11875102,and 11835009);the National Program for Support of Top-Notch Young Professionals;the Liaoning Revitalization Talents Program(XLYC1905011);the Fundamental Research Funds for the Central Universities(N2005030)。

摘　　要：Taiji,a space-based gravitational-wave observatory,consists of three satellites forming an equilateral triangle with arm length of 3×10^6 km,orbiting around the Sun.Taiji is able to observe the gravitationalwave standard siren events of massive black hole binary(MBHB)merger,which is helpful in probing the expansion of the universe.In this paper,we preliminarily forecast the capability of Taiji for improving cosmological parameter estimation with the gravitational-wave standard siren data.We simulate fiveyear standard siren data based on three fiducial cosmological models and three models of MBHB’s formation and growth.It is found that the standard siren data from Taiji can effectively break the cosmological parameter degeneracies generated by the cosmic microwave background(CMB)anisotropies data,especially for dynamical dark energy models.The constraints on cosmological parameters are significantly improved by the data combination CMB+Taiji,compared to the CMB data alone.Compared to the current optical cosmological observations,Taiji can still provide help in improving the cosmological parameter estimation to some extent.In addition,we consider an ideal scenario to investigate the potential of Taiji on constraining cosmological parameters.We conclude that the standard sirens of MBHB from Taiji will become a powerful cosmological probe in the future.太极计划是一个引力波空间探测项目,计划发射3颗绕日轨道卫星,组成一个各自相距300万公里的等边三角形卫星组,利用激光干涉方法进行中低频波段(0.1 m Hz^1.0 Hz)引力波的直接探测.太极计划可观测由超大质量双黑洞并合产生的引力波标准汽笛事件,用于探测宇宙的膨胀历史.本文对太极计划利用标准汽笛观测提升宇宙学参数测量精度的能力进行了预测.基于3种超大质量黑洞模型对太极计划5年的标准汽笛数据进行了模拟,发现其标准汽笛数据可有效打破宇宙微波背景观测所带来的固有宇宙学参数简并,特别是对于动力学暗能量模型,这种打破参数简并的作用尤为显著.当前基于电磁观测的宇宙学探针已可以极高的精度测量宇宙学参数,即便如此,太极计划的标准汽笛观测仍能在一定程度上帮助进一步改善宇宙学参数测量,并在未来为我们提供极为重要的宇宙学探针.

关 键 词：TAIJI Space-based gravitational-wave observatory Standard sirens Cosmological parameter estimation Dark energy 

分 类 号：P159[天文地球—天文学]