Fig. 2: Results of Monte Carlo simulations used to calibrate eclipse false-alarm probabilities.

Vertical lines show the measured log likelihood (\(\log {{{\mathcal{L}}}}\)) values, maximized over eclipse widths, for each pulsar. Those for pulsars with significant eclipses are marked by coloured lines. The coloured curves show the false-alarm probabilities from simulations using the distributions of photon weights from each of the five eclipsing pulsars. Horizontal dashed lines show the corresponding false-alarm probabilities according to the Monte Carlo calibration. The dotted and solid black curves show the empirical survival function (that is, the fraction of pulsars that survive a given \(\log {{{\mathcal{L}}}}\) threshold) for the real population of spiders studied here, before and after removing the five pulsars with significant eclipses, respectively. The diagonal dashed line is an extrapolation of the fit to the simulated false-alarm probability curves used to estimate the false-alarm probabilities for the most significant eclipses.