Constraints on ultraslow-roll inflation from the third LIGO-Virgo observing run
Bo Mu, Gong Cheng, Jing Liu, Zong‐Kuan Guo
Abstract
The nonattractor evolution in ultraslow-roll (USR) inflation results in the amplification of superhorizon curvature perturbations and then induces a strong and detectable stochastic gravitational wave background. In this paper, we search for such a stochastic gravitational wave background in data from the third LIGO-Virgo observing run and place constraints on the USR inflationary models. The $e$-folding number of the USR phase are constrained to be $\mathrm{\ensuremath{\Delta}}N\ensuremath{\lesssim}2.9$ at the 95% confidence level and the power spectrum of curvature perturbations amplified during the USR phase is constrained to be ${\mathrm{log}}_{10}{P}_{R\mathrm{p}}<\ensuremath{-}1.7$ at the scales $2.9\ifmmode\times\else\texttimes\fi{}{10}^{5}\text{ }\text{ }{\mathrm{pc}}^{\ensuremath{-}1}\ensuremath{\lesssim}k\ensuremath{\lesssim}1.7\ifmmode\times\else\texttimes\fi{}{10}^{11}\text{ }{\mathrm{pc}}^{\ensuremath{-}1}$. Besides, we forecast the ability of future experiments to constrain USR inflation, and find ${P}_{R\mathrm{p}}\ensuremath{\lesssim}{10}^{\ensuremath{-}3.6}$ for LISA and Taiji, ${P}_{R\mathrm{p}}\ensuremath{\lesssim}{10}^{\ensuremath{-}3.3}$ for Cosmic Explore and Einstein Telescope, ${P}_{R\mathrm{p}}\ensuremath{\lesssim}{10}^{\ensuremath{-}5.5}$ for DECIGO and Big Bang Observer, and ${P}_{R\mathrm{p}}\ensuremath{\lesssim}{10}^{\ensuremath{-}5.2}$ for Square Kilometre Array.