CAPTION:
Low frequency astrophysical gravitational wave background. This figure shows a suggested LISA sensitivity curve with signal-to-noise ratio of 5, integrated for 1 year. Massive black hole binaries at redshift of 3 for various mass combinations are plotted at 1 year, 0.1 years and just before coalescence of the binary. The possible massive black hole binary confusion noise threshold is plotted in green for the optimistic and pessimistic cases of: 1) all galaxies harboring black holes and all of them coalescing, and 2) only a percentage of galaxies harboring black holes, and of those only those with a smaller mass of the binary larger than 3 x 10^5 solar masses coalescing. Both curves are below the LISA sensitivity, so it seems that LISA will not be affected by a low frequency astrophysical gravitational wave background.