Cross-correlation of the astrophysical gravitational-wave background with galaxy clustering

Abstract

We investigate the correlation between the distribution of galaxies and the predicted gravitational-wave background of astrophysical origin. We show that the large angular scale anisotropies of this background are dominated by nearby nonlinear structure, which depends on the notoriously hard to model galaxy power spectrum at small scales. In contrast, we report that the cross-correlation of this signal with galaxy catalogues depends only on linear scales and can be used to constrain the average contribution to the gravitational-wave background as a function of time. Using mock data based on a simplified model, we explore the effects of galaxy bias, angular resolution and the matter abundance on these constraints. Our results suggest that, when combined with galaxy surveys, the gravitational-wave background can be a powerful probe for both gravitational-wave merger physics and cosmology.

Search for anisotropic gravitational-wave backgrounds using data from Advanced LIGO and Advanced Virgo’s first three observing runs

“…The background may also include signals of cosmological origin, i.e., produced in the early Universe during an inflationary epoch [19][20][21][22][23][24][25][26][27], or as a direct result of phase transitions [28][29][30], primordial black hole mergers [31][32][33][34], or other associated phenomena [35]. Different models could, in principle, be distinguished by characteristic features in the angular distribution [36][37][38][39][40][41][42][43][44][45][46][47]. For example, cosmic strings have an angular power spectrum which is sharply peaked at small multipoles [48,49], while neutron stars in our Galaxy would trace out the Galactic plane [50,51].…”

Detecting the anisotropic astrophysical gravitational wave background in the presence of shot noise through cross-correlations

“…Note that our analysis differs significantly from Ref. [17], where the constraints derived on posterior distributions are only cosmic variance limited.…”

“…and by construction we have 1 + ∆ G p = 1 as ∑ r W (r) dr = 1. Assuming purely Poisson statistics for both N G r,p and N L GW r,p , we can now compute the variance of the different auto-and cross-correlations [17]. AGWB auto-correlation:…”

Stochastic Gravitational-Wave Backgrounds: Current Detection Efforts and Future Prospects

“…This is analysed in [123,124] for the anisotropic background, and it is found that the white noise component dominates current LIGO and Virgo detectors; however, the planned upgrades of these detectors and the future 3G detectors may be sufficient to curb this effect. As discussed in [125,126], another strategy to mitigate the shot noise is to cross-correlate the GW signal with a galaxy catalogue, as this cross-correlation spectrum has a much lower level of shot noise. Furthermore, as GW sources are finite in time, then Poisson statistics dictate that this noise decays as the inverse of the observation time; hence, long observing runs will progressively mitigate this effect.…”