Unraveling the early universe’s equation of state and primordial black hole production with PTA,BBN,and CMB observations  

作　　者：Qing-Hua Zhu Zhi-Chao Zhao Sai Wang Xin Zhang 朱庆华;赵志超;王賽;张鑫(Department of Physics and Chongqing Key Laboratory for Strongly Coupled Physics,Chongqing University,Chongqing 401331,China;Department of Applied Physics,College of Science,China Agricultural University,Qinghua East Road,Beijing 100083,China;Theoretical Physics Division,Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100049,China;Key Laboratory of Cosmology and Astrophysics(Liaoning)&College of Sciences,Northeastern University,Shenyang 110819,China;National Frontiers Science Center for Industrial Intelligence and Systems Optimization,Northeastern University,Shenyang 110819,China;Key Laboratory of Data Analytics and Optimization for Smart Industry(Ministry of Education),Northeastern University,Shenyang 110819,China)

机构地区：[1]Department of Physics and Chongqing Key Laboratory for Strongly Coupled Physics,Chongqing University,Chongqing 401331,China [2]Department of Applied Physics,College of Science,China Agricultural University,Qinghua East Road,Beijing 100083,China [3]Theoretical Physics Division,Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100049,China [4]Key Laboratory of Cosmology and Astrophysics(Liaoning)&College of Sciences,Northeastern University,Shenyang 110819,China [5]National Frontiers Science Center for Industrial Intelligence and Systems Optimization,Northeastern University,Shenyang 110819,China [6]Key Laboratory of Data Analytics and Optimization for Smart Industry(Ministry of Education),Northeastern University,Shenyang 110819,China

出　　处：《Chinese Physics C》2024年第12期212-220,共9页中国物理C（英文版）

基　　金：China(2021YFC2203001)and the National Natural Science Foundation of China(12005016);partially supported by the National Natural Science Foundation of China(12175243);the National Key R&D Program of China(2023YFC2206403);the Science Research Grants from the China Manned Space Project(CMS-CSST-2021-B01);the Key Research Program of the Chinese Academy of Sciences(XDPB15);supported by the National SKA Program of China(2022SKA0110200,2022SKA0110203);the National Natural Science Foundation of China(11975072,11835009,11805031);supported by High-performance Computing Platform of China Agricultural University。

摘　　要：Pulsar timing array(PTA)data releases show strong evidence for a stochastic gravitational-wave background in the nanohertz band.When the signal is interpreted by a scenario of scalar-induced gravitational waves(SIGWs),we encounter overproduction of primordial black holes(PBHs).We wonder if varying the equation of state(EoS)of the early Universe can resolve this issue and thereby lead to a consistent interpretation of the PTA data.Analyzing a data combination of PTA,big-bang nucleosynthesis,and cosmic microwave background,we find that an epoch with EoS w~O(10^(-2))between the end of inflation and the onset of radiation domination can significantly suppress the production of PBHs,leading to alleviation of the PBH-overproduction issue.With the inferred interval w=0.44_(-0.40)^(+0.52)at 95%confidence level,our scenario can interpret the PTA data just as well as the conventional scenario of SIGWs produced during the radiation domination.

关 键 词：physics of the early universe gravitational waves primordial black hole pulsar timing arrays 

分 类 号：P145.8[天文地球—天体物理] P159[天文地球—天文学]