4 papers
Acoustic gravitational waves from primordial curvature perturbations
Zhuan Ning, Zi-Yan Yuwen, Xiang-Xi Zeng +2
Standard perturbative calculations of scalar-induced gravitational waves (SIGWs) have neglected nonperturbative effects in the large-amplitude regime. We develop a hybrid numerical…
Scalar-induced gravitational waves with non-Gaussianity up to all orders
Xiang-Xi Zeng, Zhuan Ning, Rong-Gen Cai +1
Scalar-induced gravitational waves (SIGWs) are ubiquitous in many early-Universe processes accompanied by non-Gaussianity; while Gaussian perturbation can generate significant SIGW…
Sound waves from primordial black hole formations
Zhuan Ning, Xiang-Xi Zeng, Zi-Yan Yuwen +3
We present a numerical investigation of primordial black hole (PBH) formation from super-horizon curvature perturbations and the subsequent generation and propagation of sound wave…
Relic gravitational waves from primordial gravitational collapses
Xiang-Xi Zeng, Zhuan Ning, Zi-Yan Yuwen +3
A large primordial density perturbation of the Hubble scale will gravitationally collapse, generating an outgoing sound shell, whether or not a primordial black hole (PBH) is forme…