ON THE GRAVITATIONAL-WAVE NOISE FROM UNRESOLVED EXTRAGALACTIC BINARIES

We calculate stochastic gravitational wave background produced by extr agalactic merging binary white dwarfs at the LISA frequencies 10(-3) - 10(-2) Hz with account of a strong evolution of global star formation rate in the Universe recently established observationally. We show th at for the observed global star formation history and modern cosmologi cal models the extragalactic background is an order df magnitude small er than the mean Galactic value. An early star formation burst at high redshifts can bring it at a higher level but still a few times lower than the mean Galactic one.