Scalar-induced gravitational waves with non-Gaussianity up to all orders
Abstract
Scalar-induced gravitational waves (SIGWs) are ubiquitous in many early-Universe processes accompanied by non-Gaussianity; while Gaussian perturbation can generate significant SIGWs, computations of SIGWs can be significantly affected and enhanced if the scalar perturbations have some degree of non-Gaussianity; hence, precise calculations of these kinds of SIGWs involve a full understanding of non-Gaussianity. In this Letter, we propose to use the lattice simulations to directly calculate the energy density spectra of SIGWs with non-Gaussianity up to all orders. Our proposal has been first verified to match the existing semi-analytical results with non-Gaussianity, and then applied to more general cases, including high-order primordial non-Gaussianities, the logarithmic dependence in curvature perturbations, the curvaton model, and the ultra slow-roll model. We find that even a modest non-Gaussianity can significantly alter ultraviolet behaviors in SIGW spectra, necessitating special cautions in future detections as well as mutual constraints on/from primordial black holes.
Keywords
Cite
@article{arxiv.2508.10812,
title = {Scalar-induced gravitational waves with non-Gaussianity up to all orders},
author = {Xiang-Xi Zeng and Zhuan Ning and Rong-Gen Cai and Shao-Jiang Wang},
journal= {arXiv preprint arXiv:2508.10812},
year = {2026}
}
Comments
v1, 6 figures, 5 pages + Supplemental Materials (with 2 figures); v2, largely extended supplemental materials with 7 figures. The Python/PyTorch code SimuSIGW with the Fourier Pseudo-Spectral method is now available at https://github.com/ZengXiang-Xi/SimuSIGW/tree/main