Abstract The standard Λ Cold Dark Matter (ΛCDM) cosmological model provides a good
description of a wide range of astrophysical and cosmological data. However, there are a …

We provide a review on the state-of-the-art of gravitational waves induced by primordial
fluctuations, so-called induced gravitational waves. We present the intuitive physics behind …

We review recent trends in inflationary dynamics in the context of viable modified gravity
theories. After providing a general overview of the inflationary paradigm emphasizing on …

This Horizon Study describes a next-generation ground-based gravitational-wave
observatory: Cosmic Explorer. With ten times the sensitivity of Advanced LIGO, Cosmic …

In this work we present several characteristic examples of theories of gravity and particle
physics scenarios that may yield an observable energy spectrum of stochastic primordial …

The 100 years since the publication of Albert Einstein's theory of general relativity saw
significant development of the understanding of the theory, the identification of potential …

Gravitational wave (GW) detection in space probes the GW spectrum that is inaccessible
from the Earth. In addition to the LISA project led by the European Space Agency, and the …

Multiple pulsar timing array (PTA) collaborations recently announced the evidence of
common-spectral processes caused by gravitational waves (GWs). These can be the …

Several pulsar timing arrays including NANOGrav, EPTA, PPTA, and CPTA have recently
reported the observation of a stochastic background of gravitational wave spectrum in the …

The symmetry breaking of grand unified gauge groups in the early Universe often leaves
behind relic topological defects such as cosmic strings, domain walls, or monopoles. For …