A. Ricciardone

TL;DR: There is a persistent interest in extending cosmology beyond the standard model, ΛCDM, motivated by a range of apparently serious theoretical issues, involving such questions as the cosmological constant problem, the particle nature of dark matter, the validity of general relativity on large scales, the existence of anomalies in the CMB and on small scales, and the predictivity and testability of the inflationary paradigm as mentioned in this paper.

TL;DR: In this article, the challenges and gains expected in high-frequency gravitational wave searches at frequencies above the LIGO/Virgo band are discussed. But the authors focus on the MHz and GHz range and highlight the most promising sources.

TL;DR: In this paper, the angular anisotropies of the GW energy density were studied using a Boltzmann approach, which is an important tool to disentangle the different cosmological and astrophysical contributions to the SGWB.