Gravitational wave memory produced by cosmic background radiation

Zhoujian Cao, Xiaokai He, Zhi-Chao Zhao

Published 2022-10-31Version 1

It is well known that energy fluxes will produce gravitational wave memory. The gravitational wave memory produced by background including cosmic microwave background (CMB), cosmic neutrino background (C$\nu$B), and gravitational wave background is investigated in this work. We construct a theory relating the gravitational wave memory strength to the energy flux of a stochastic background. We find that the resulted gravitational wave memory behaves as a constantly varying metric tensor. Such a varying metric tensor will introduce a quadrupole structure to the universe expansion. The gravitational wave memory due to the CMB is too small to be detected. But the gravitational wave memory due to the C$\nu$B and the gravitational wave background is marginally detectable. Interestingly, such detection can be used to estimate the neutrino masses and the properties of the gravitational wave background.