Astrophysical and cosmological relevance of the high-frequency features in the stochastic gravitational-wave background

The stochastic gravitational-wave background (SGWB) produced by merging neutron stars exhibits a peak in the kHz band. In this paper, we develop a theoretical framework to exploit this distinctive feature through a Markov Chain Monte Carlo analysis using a simulated dataset of SGWB measurements within this frequency range. The aim is to use the SGWB peak as an observable to constrain a set of astrophysical and cosmological parameters that accurately describe the sources of the SGWB. We examine how variations in these parameters impact the morphology of the SGWB and investigate the necessary sensitivity to effectively constrain them. Given our priors on astrophysical and cosmological parameters, and assuming a power-law integrated sensitivity curve of the order of ${10}^{-11}$ between 1 kHz and 5 kHz, we show that the values of the chirp mass and common envelope efficiency of the binary systems are retrieved with percent accuracy. Furthermore, the method allows for the reconstruction of the cosmological expansion history populated by these binaries, encompassing the Hubble constant, matter abundance, and the effective equation of state of dark energy.