Aperture mass peak counts for f(R) with f_R0 = −10⁻⁵ and a varying sum of neutrino masses m_ν. Data points represent the mean over 256 realisations of each simulated cosmology and are plotted at scales (ϑ₁, …, ϑ₇ = 0.293′, 0.586′, 1.17′, 2.34′, 4.69′, 9.34′, 18.8′). The abundance of peaks above a 3σ threshold is shown in the left panel, and above a 5σ threshold in the right panel. An order of magnitude more peaks are detected at each scale with the lower threshold, although deviations from ΛCDM, as well as among the different m_ν cases of f₅(R), are more pronounced with the higher threshold. This indicates that differences between models at this redshift are mostly contained in the highest amplitude peaks. Compared to the M_ap moments, peak counts interestingly do not very well distinguish between models with different neutrino mass, but they do distinguish modified from standard gravity, at least at certain scales.