Abstract
The pulsar timing array(PTA)collaborations have recently reported compelling evidence for a stochastic signal consistent with a gravitational-wave background.In this paper,we combine the latest data sets from NANOGrav,PPTA,and EPTA to explore cosmological interpretations for the PTA signal from first-order phase transitions,domain walls,and cosmic strings,respectively.We find that the domain wall model is strongly disfavored with the Bayes factors compared with the first-order phase transitions and cosmic strings being 1/90 and 1/189,respectively,breaking the degeneracy among these models in individual data set.We also find that:(1)a strong phase transition at temperatures below the electroweak scale is favored,and the bubble collisions make the dominant contribution to the energy density spectrum;(2)a small reconnection probability p＜1.55 × 10-1 allowed by strings in(super)string theory is favored at the 95％confidence level,and ground-based detectors can further constrain the parameter space.
基金项目
国家自然科学基金(12250010)
国家自然科学基金(11975019)
国家自然科学基金(11991052)
国家自然科学基金(12047503)
中国科学院前沿科学重点研究计划(ZDBS-LY-7009)
CAS Project for Young Scientists in Basic Research(YSBR-006)
中国科学院重点研究项目(XDPB15)
国家自然科学基金(12247176)
国家自然科学基金(12247112)
China Postdoctoral Science Foundation Fellowship(2022M710429)
维普
万方数据