Name: Shubham Singh
Affiliation: National Centre for Radio Astrophysics (NCRA-TIFR)
Conference ID : ASI2022_288
Title : Long period pulsars with short duty-cycle: a missing population?
Authors : Shubham Singh (NCRA), Jayanta Roy (NCRA), Ujjwal Panda (NCRA), Bhaswati Bhattacharyya (NCRA), Ben Stappers (University of Manchester), and Vincent Morello (University of Manchester)
Abstract Type: Poster
Abstract Category : Stars, ISM and Galaxy
Abstract : The duty-cycle of a pulsar defines the fraction of its rotational period providing the pulsed emissions. Duty-cycle is a function of geometry and period of the pulsar. For the currently known pulsar population, there is a lower boundary line (LBL) in the duty-cycle vs period plot with sqrt(1/P) dependence. No pulsar from the current population has a small enough duty-cycle to be placed beyond this lower boundary line. The conventional pulsar search with Fast Fourier Transform (FFT) followed by incoherent harmonic summing over a limited number of harmonics encounters an inherent bias against small duty-cycle pulsars having signals distributed over a large number of harmonics in the Fourier domain. In contrast, the Fast Folding Algorithm (FFA) provides a phase-coherent search method, based on folding the time series at closely spaced trial periods. FFA is known to have superior sensitivity for any non-accelerated periodic signal and the search method has uniform sensitivity for all duty-cycles. We present the discovery of 4 pulsars with processing GMRT High-Resolution Southern Sky (GHRSS) survey data with a newly implemented FFA search pipeline. The newly discovered pulsars are pushing the lower boundary line in the duty-cycle vs period plot highlighting the possibility of missing such a population from the conventional FFT search. Three out of four new pulsars are having very narrow duty-cycles placing them at a hitherto unexplored parameter space in the duty-cycle vs period plot below the known lower boundary line (LBL). One of these pulsars has a very narrow duty cycle similar to the pulsar J2144-3933 which has the smallest known duty-cycle. This pulsar with a period of 1.67s also shows nulling. With ongoing effort on searching for pulsars, we anticipate the future discovery of long-period pulsars aiding towards a better understanding of the parameter space.