Discovery of 37 new pulsars through GPU-accelerated reprocessing of archival data of the Parkes multibeam pulsar survey

Abstract

We present the discovery of 37 pulsars from ∼ 20 years old archival data of the Parkes Multibeam Pulsar Survey using a new FFT-based search pipeline optimised for discovering narrow-duty cycle pulsars. When developing our pulsar search pipeline, we noticed that the signal-to-noise ratios of folded and optimised pulsars often exceeded that achieved in the spectral domain by a factor of two or greater, in particular for narrow duty cycle ones. Based on simulations, we verified that this is a feature of search codes that sum harmonics incoherently and found that many promising pulsar candidates are revealed when hundreds of candidates per beam with even with modest spectral signal-to-noise ratios of S/N∼5–6 in higher-harmonic folds (up to 32 harmonics) are folded. Of these candidates, 37 were confirmed as new pulsars and a further 37 would have been new discoveries if our search strategies had been used at the time of their initial analysis. While 19 of these newly discovered pulsars have also been independently discovered in more recent pulsar surveys, 18 are exclusive to only the Parkes Multibeam Pulsar Survey data. Some of the notable discoveries include: PSRs J1635−47 and J1739−31, which show pronounced high-frequency emission; PSRs J1655−40 and J1843−08, which belong to the nulling/intermittent class of pulsars; and PSR J1636−51, which is an interesting binary system in a ∼0.75 d orbit and shows hints of eclipsing behaviour – unusual given the 340 ms rotation period of the pulsar. Our results highlight the importance of reprocessing archival pulsar surveys and using refined search techniques to increase the normal pulsar population.

The Green Bank 820 MHz Pulsar Survey. I. Survey Overview and Initial Results

“…Consequently, employing greater number of harmonics can increase the likelihood of a candidate appearing in the candidate list. Sengar et al (2023) found that on average the folded S/Ns for such faint narrow duty cycle pulsars can be 1.5-2.0 times higher than their spectral S/Ns. This underscores the importance of folding candidates from the FFT noise floor, i.e., those with a spectral S/N (S/N FFT ) close to five, in order to effectively target faint narrow duty cycle pulsars.…”

“…Both strategies have been successful, and both are necessary to understand the underlying pulsar population. These searches are made more efficient with ever improving sensitivity limits provided by new instruments (Braun et al 2019;Jiang et al 2019;Gautam et al 2022) and candidate sifting techniques (Karako-Argaman et al 2020;Yu et al 2020;Sengar et al 2023).…”

“…Given the recent success in reprocessing pulsar surveys through optimized search and classification methodologies (e.g., Morello et al 2019;Sengar et al 2023), we processed the GBT820 data using pipeline and candidate classification approaches similar to those outlined in Sengar et al (2023). The pipeline is built around a GPU-based pulsar search library PEASOUP, which uses a time-domain resampling algorithm (Johnston & Kulkarni 1991) to search for binary pulsars.…”

“…These sources range more than 3 orders of magnitude in period and dispersion measure (DM), and include nearly 400 binary systems. However, population models predict tens of thousands more pulsars in the Galaxy beamed toward Earth yet to be discovered, if only we know where (and how) to look (Swiggum et al 2014;Venkatraman Krishnan et al 2020;Sengar et al 2023;Zhou et al 2023;Dong et al 2023). Every new pulsar provides an opportunity for improving our understanding of the population.…”

The Green Bank North Celestial Cap Survey. IX. Timing Follow-up for 128 Pulsars

“…29 During the summer of 2022, the final GBNCC survey positions were observed (aside from 500 points which will be reobserved for reasons related to radio frequency interference (RFI) and observation complications). Efforts to identify new pulsars are continuing, both with our existing pipeline and with new pipelines that improve sensitivity to certain regions of parameter space (Sengar et al 2023). For this study, we instead focus on the continued timing of prior discoveries by connecting archival data with new observations.…”