An Efficient Search for the Faint Population of Long Period Pulsars

The conventional periodicity search, based on the fast Fourier transform (FFT) of the time series, has two major drawbacks while searching for long period pulsars. Long period pulsars often have short duty cycles and the FFT based search with harmonic summing over a limited harmonic space is less sensitive for short duty cycles. The FFT search is also highly vulnerable to rednoise in the radio telescope data, reducing its sensitivity for longer periods. Since the current population of radio pulsars is mostly discovered by the FFT based search, there is a strong possibility of a missing population of long period and short duty cycle pulsars. An alternative search method for non-accelerated periodic signals is the fast folding algorithm (FFA), which has a uniform response for all periods and duty cycles. The FFA search provides an unbiased way to search for periodic signals with superior sensitivity. Though sufficiently bright population of long period pulsars can be discovered in single pulse searches, a suitable periodicity search along with an increase in integration time per pointing is required in major pulsar surveys to discover the fainter population of long period pulsars.