The GMRT High Resolution Southern Sky Survey for pulsars and transients $-$ IV: Discovery of 4 new pulsars with an FFA search

TL;DR

This paper reports the discovery of four new pulsars using a Fast Folding Algorithm (FFA) search in the GMRT High Resolution Southern Sky survey, demonstrating FFA's superior sensitivity for detecting long-period and short duty cycle pulsars.

Contribution

The study introduces an FFA-based pipeline for pulsar searches, revealing new pulsars and highlighting FFA's effectiveness over traditional FFT methods for certain pulsar populations.

Findings

Discovered 4 new pulsars with FFA search.

Identified a nulling pulsar with 90% nulling fraction.

Faster detection of long-period and short duty cycle pulsars.

Abstract

The fast Fourier transform (FFT) based periodicity search methods provide an efficient way to search for millisecond and binary pulsars but encounter significant sensitivity degradation while searching for long period and short duty cycle pulsars. An alternative to FFT-based search methods called the Fast Folding Algorithm (FFA) search, provides superior sensitivity to search for signals with long periods and short duty cycles. In the GMRT High Resolution Southern Sky (GHRSS) survey, we are using an FFA-based pipeline to search for isolated pulsars in a period range of 100 ms to 100 s. We have processed 2800 degree$^2$ of the sky coverage away from the Galactic plane and discovered 6 new pulsars. Here, we report the discovery of 4 of these pulsars with the FFA search pipeline. This includes a narrow duty cycle pulsar, J1936$-$30, which shows nulling behavior with an extreme nulling fraction of $\sim 90\%$. Two of the GHRSS discoveries from the FFA search lie in narrow duty cycle ranges beyond the limit of the existing population. The implementation of FFA search in the GHRSS survey and other pulsar surveys is expected to recover the missing population of long period and short duty cycle pulsars.