Cosmo

The detection of compact binary mergers with sub-solar masses at gravitational-wave observatories could mark the groundbreaking discovery of primordial black holes. Concurrently, evidence for a nHz stochastic gravitational wave background observed by pulsar timing arrays could suggest a non-astrophysical origin, potentially arising from scalar-induced gravitational waves. In this work, we analyze the connection between the two phenomena in the case where they share a common origin: the collapse of large primordial curvature perturbations in the early universe.

We present updated constraints on the abundance of primordial black holes (PBHs) dark matter from the high-redshift Lyman-$\alpha$ forest data from MIKE/HIRES experiments. Our analysis leverages an effective field theory (EFT) description of the 1D flux power spectrum, allowing us to analytically predict the Lyman-&alpha fluctuations on quasi-linear scales from first principles.

We derive a new metastability bound for the Higgs mass parameter. When the bound for the positive mass parameter is significantly more restrictive than or comparable to its counterpart for the negative, it may offer an explanation for the spontaneous symmetry breaking itself.

Recent observations have granted to us two unique insights into the early Universe: the presence of a low-frequency stochastic gravitational wave background detected by the NANOGrav and Pulsar Timing Array experiments and the emergence of unusually massive galaxy candidates at high redshifts reported by the James Webb Space Telescope. We consider the possibility that both observations have a common origin, namely supermassive primordial black holes.