Probing the primordial universe with gravitational waves detectors

Abstract

The spectrum of primordial gravitational waves (GWs), especially its tilt n_T, carries significant information about the primordial universe. Combining recent aLIGO and Planck2015+BK14 data, we find that the current limit is n_T=0.016^+0.614_-0.989 at 95% C.L. We also estimate the impacts of Einstein Telescope and LISA on constraining n_T. Moreover, based on the effective field theory of cosmological perturbations, we make an attempt to confront some models of early universe scenarios, which produce blue-tilted GWs spectrum (n_T>0), with the corresponding datasets.