CνB Damping of Primordial Gravitational Waves and the Fine-Tuning of the CγB Temperature Anisotropy

Figure 2

Time-averaged values of as function of for RD (red lines) and RMD (black lines) background cosmic inventories. Results are for vanishing anisotropic stress, with (dotted lines), for (dashed lines) and for (solid lines). Notice the fake resonance effect for modes with followed by the neutrinos damping effect which is more relevant for scales deep inside the horizon.