Figure 15
From: Stochastic backgrounds of relic gravitons: a theoretical appraisal
The bounds stemming from the amount of extra-relativistic species at the epoch of the synthesis of light nuclei are applied to the relic graviton spectra from the stiff epoch (plot at the left). The detectability constraint (full line in the plot at the right) stemming from the putative sensitivities of wide-band interferometers in their advanced version. The points corresponding to the spectral energy density should lie above the full lines to be potentially interesting for those instruments.