Pulsar Gleaners: Discovery of 19 Pulsars in FAST Archival Data at $|b|<5°$ and Decl.$<-5°$

Abstract: We report the discovery of 19 new pulsars identified from archival observations of the Five-hundred-meter Aperture Spherical radio Telescope (FAST) within Galactic latitudes $|b|<5°$ and declinations ${\rm Decl.}<-5°$. The dataset was recorded using FAST's $L$-band 19-beam receiver and covered $\sim 3.6~{\rm deg}^2$ with a cumulative integration time of $\sim$ 500 hr and a total raw data volume of $\sim$ 700 TB. Our search employed fast Fourier transform (FFT)-based and fast folding algorithm (FFA)-based periodic searches, and the single-pulse search. These new pulsars have spin periods range from 0.03 to 5.54 s. Two have periods under 0.1 s, suggesting they are likely young pulsars or mildly recycled pulsars. Four pulsars exhibit dispersion measures (DMs) exceeding $1000~{\rm pc~cm^{-3}}$ with PSR J1839$-$0558t having the highest value in our sample at $\sim 1271~{\rm pc~cm^{-3}}$, providing valuable samples for pulsar studies in the high-DM regime. Two rotating radio transients, PSRs J1836$-$0552t and J1847$-$0624t, were detected by FFA and single-pulse searches but failed with the FFT-based searches. In addition, three faint pulsars that were also missed by FFT-based searches were successfully detected using FFA. These discoveries demonstrate the critical role of FFA in uncovering faint, long-period, and sporadic pulsars, and highlight the significant potential of FAST archival data, especially when combined with longer integration times and complementary search techniques, to reveal rare and weak pulsar populations.