The authors investigate whether the NANOGrav signal is consistent with the stochastic gravitational-wave background (SGWB) predicted by string cosmology models. They perform Bayesian parameter estimation on the NANOGrav 15-year data set to constrain the key parameters of a string cosmology model:
The analysis yields constraints of fs = 1.2^(+0.6)(-0.6) × 10^(-8) Hz and Ωs_gw = 2.9^(+5.4)(-2.3) × 10^(-8), consistent with theoretical predictions from string cosmology. However, the current NANOGrav data is not sensitive to the Hr parameter.
The authors also compare the string cosmology model to a simple power-law model using Bayesian model selection, finding a Bayes factor of 2.2 in favor of the string cosmology model. This suggests that the string theory-based model provides a slightly better fit to the NANOGrav data than the supermassive black hole binary model, although the evidence is considered weak.
The results demonstrate the potential of pulsar timing arrays to constrain cosmological models and study the early Universe. As pulsar timing arrays continue to improve their sensitivities and gather more data, even more stringent constraints on the string cosmology parameters can be expected.
To Another Language
from source content
arxiv.org
Key Insights Distilled From
by Qin Tan, You... at arxiv.org 10-01-2024
https://arxiv.org/pdf/2409.17846.pdfDeeper Inquiries