Differential 160 μm background brightness dν₁₆₀B₁₆₀ / dz as a function of redshift, in units of nW m^-2 sr^-1, in the COSMOS field (left) and GOODS field (right). The lower part of the plot shows a linear zoom between 0 and 0.5 nW m^-2 sr^-1 to show more clearly the trend of cleaned sources and AGNs. Black solid lines: total contribution of infrared galaxies. Solid red lines: contribution from resolved sources only. Solid blue line: contribution from AGN only. Dashed line: Lagache et al. (2004) model, with S₂₄ > 80   μ Jy cut. Dotted line: Le Borgne et al. (2009) model, with S₂₄ > 80   μ Jy cut. Dot-dash line: Valiante et al. (2009). Dot-dot-dot-dash line: Bethermin et al. (2010c) model, with S₂₄ > 80   μ Jy cut. Models are presented and discussed in Sect. 4.5 and Fig. 10.