Parkes observations for project P1152 semester 2022APRS_15

A large population of millisecond pulsars (MSPs) is expected in the Galactic bulge and is supported, among others, by the existence of a spatially extended gamma-ray excess emission discovered in Fermi-LAT data towards the inner Galaxy. Discovering MSPs in the Galactic bulge, would be a major breakthrough with strong impact onto several fields. In Berteaud et al. [2021a, 2021b], we have designed a new method to select bulge MSP candidates among Chandra X-ray cataloged sources. We also analysed imaging data of the VLA and identified 5 potential bulge MSP candidates, detected both with Chandra and VLA. Here we propose to follow up these 5 sources with the UWL receiver system on Parkes, which has the unique potential of probe their MSP nature thanks to multi-band, deep, observations. With the requested time, for two high-priority candidates, we will be able identify any bulge MSP with a pulse period P > 1 ms. Three targets at lower priority can be identified as bulge MSP if their period is larger than 4 ms. Our goal is to provide the first multi-wavelength diagnostics of bulge MSPs, gather information about the MSP/pulsar ratio among the bulge X-ray candidates, and, finally, unveil the nature of the mysterious Fermi-LAT excess.

银河核球（Galactic bulge）中预计存在大量毫秒脉冲星（millisecond pulsars, MSPs），而费米LAT（Fermi-LAT）观测数据中朝向银心区域发现的空间延展伽马射线过剩辐射，便是支持这一推测的关键证据之一。在银河核球中发现毫秒脉冲星，将是一项具有里程碑意义的突破，对诸多研究领域产生深远影响。在Berteaud等人[2021a, 2021b]的研究中，我们开发了一种全新方法，用于从钱德拉X射线源目录收录的天体中筛选核球毫秒脉冲星候选体。我们还对甚大阵（Very Large Array, VLA）的成像数据开展了分析，识别出5个同时被钱德拉和甚大阵探测到的潜在核球毫秒脉冲星候选体。本研究计划利用帕克斯望远镜（Parkes Telescope）上的UWL接收机系统（UWL receiver system）对这5个候选体开展后续观测：该系统具备多波段深场观测的独特能力，可用于验证这些天体的毫秒脉冲星属性。根据申请的观测时长，对于2个高优先级候选体，我们将能够识别出脉冲周期P＞1 ms的核球毫秒脉冲星；对于其余3个低优先级候选体，若其脉冲周期大于4 ms，即可确认其为核球毫秒脉冲星。本研究的目标是首次实现核球毫秒脉冲星的多波段诊断，收集核球X射线候选体中毫秒脉冲星与脉冲星比率的相关数据，并最终揭开费米LAT伽马射线过剩辐射的神秘本质。