10 Hz to 1000 Hz. In this band the most likely source of the stochastic background will be an astrophysical background from binary neutron-star and stellar mass binary black-hole mergers. Detection On 11 February 2016, the LIGO and Virgo collaborations announced the first direct detection and observation of gravitational waves, which took place in September 2015. In this case, two black holes had collided to produce detectable gravitational waves. This is the first step to the potential detection of a GWB. See also Cosmic microwave background Cosmic neutrino background References External links Gravitational Wave Experiments and Early Universe Cosmology Effects of gravitation background Gravitational-wave astronomy Cosmic background radiation