Stochastic backgrounds of gravitational waves from cosmological sources - the role of dark energy

Abstract

[Abridged] We investigate the detectability of the gravitational stochastic background produced by cosmological sources in scenarios of structure formation. The model considers the coalescences of three kind of binary systems: double neutron stars, the neutron star-black hole binaries, and the black hole-black hole systems. We also included the core-collapse supernovae leaving black holes as compact remnants. We use two different dark-energy scenarios, cosmological constant and Chaplygin gas, in order to verify their influence on the cosmic star formation rate, the coalescence rates, and on the gravitational wave backgrounds. We calculate the gravitational wave signals separately for each kind of source as well as we determine their collective contribution for the stochastic background of gravitational waves. Concerning to the compact binary systems, we verify that these sources produce stochastic backgrounds with signal-to-noise ratios (S/N) ~ 1.5 (~ 0.90) for NS-NS, ~ 0.50 (~ 0.30) for NS-BH, ~ 0.20 (~ 0.10) for BH-BH for a pair of advanced LIGO detectors in the cosmological constant (Chaplygin gas) cosmology. Particularly, the sensitivity of the future third generation of detectors as the Einstein Telescope (ET) could increase the present signal-to-noise ratios by a high-factor (~ 300 - 1000) when compared to the (S/N) calculated for advanced LIGO detectors. Thus, the third generation of gravitational wave detectors could be used to reconstruct the history of star formation in the Universe as well as for contributing with the characterization of the dark energy, for example, identifying if there is evidence for the evolution of the dark energy equation-of-state parameter w(a).