Millisecond Pulsar Discoveries in an Image-based MeerKAT Survey of the Galactic Bulge

Abstract: We report on the follow-up observations of circularly polarized sources identified in the MeerKAT image-based survey of the Galactic bulge. Using the Parkes radio telescope, we observed sixteen circularly polarized sources with the UWL receiver and detected nine pulsars among which six of them are new discoveries. All pulsars are fast rotators with spin periods under 100\,ms. Among the new discoveries five are millisecond pulsars (MSPs) and one has a spin period of 55\,ms. At least four new MSPs exhibit clear signs of binary motion in their discovery observations. The dispersion measures (DMs) of these pulsars fall between 18 and 330\,pc\,cm$^{-3}$, which is lower than expected for Galactic bulge members and indicates that these pulsars lie in the foreground along the line of sight rather than within the bulge itself. This is the first time such a large number of pulsars have been confirmed via an image-based survey. These discoveries underscore the exceptional efficacy of circular polarization selection in image-based pulsar surveys, and demonstrate the powerful synergy between high-sensitivity imaging and targeted time-domain follow-up using wide-band receivers and strengthen prospects for future deep pulsation searches$-$e.g., with MeerKAT or the forthcoming SKA or DSA-2000$-$to uncover the true millisecond pulsar population in the Galactic bulge.