Maximum age of visible NSs in one-year observations in the space of the parameters of the model η − ϵ₀ for the Advanced Virgo and Einstein Telescope detectors. The left column corresponds to the signal’s ν harmonic, the right column the 2ν harmonic. The colour represents the maximum age in the population for a given model. The blue vertical dashed line indicates models where η is equal to the magnetic field decay Δ (see Table 1). (a) ν. V1 Advanced Virgo detector. (b) 2ν. V1 Advanced Virgo detector. (c) ν. Einstein Telescope detector, configuration D. (d) 2ν. Einstein Telescope detector, configuration D.