2019/12/19 by N. Bartolo, Nicola Bartolo, Daniele Bertacca +10 · 3 citations
Physics and Astronomy · #Anisotropy #Astrophysics #Black Holes and Theoretical Physics #Classical mechanics #Cosmic microwave background #Cosmology #Cosmology and Gravitation Theories #Gravitational wave #Gravitational wave background #Non-Gaussianity #Physics #Pulsars and Gravitational Waves Research #Quantum mechanics #Theoretical physics #Universe #astro-ph.CO
paper · pdf · doi:10.1103/physrevd.102.023527
published as Phys. Rev. D 102, 023527 (2020) · 26 pages + Appendices: 2 figures
arxiv created 2019/12/19 · openalex publication_date 2020/07/16 · arxiv updated 2020/07/22 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
A future detection of the stochastic gravitational wave background (SGWB) with gravitational wave (GW) experiments is expected to open a new window on early universe cosmology and on the astrophysics of compact objects. In this paper we study SGWB anisotropies, that can offer new tools to discriminate between different sources of GWs. In particular, the cosmological SGWB inherits its anisotropies both (i) at its production and (ii) during its propagation through our perturbed universe. Concerning (i), we show that it typically leads to anisotropies with order one dependence on frequency. We then compute the effect of (ii) through a Boltzmann approach, including contributions of both large-scale scalar and tensor linearized perturbations. We also compute for the first time the three-point function of the SGWB energy density, which can allow one to extract information on GW non-Gaussianity with interferometers. Finally, we include nonlinear effects associated with long wavelength scalar fluctuations, and compute the squeezed limit of the 3-point function for the SGWB density contrast. Such limit satisfies a consistency relation, conceptually similar to that found in the literature for the case of cosmic microwave background perturbations.