Parkes observations for project P1381 semester 2025OCTS_02

The Galactic bulge is theorized to host a rich population of millisecond pulsars (MSPs), but direct detections have been severely hampered by high interstellar scattering, dispersion, and background noise near the Galactic center. These MSPs, if confirmed, would serve as powerful tools for testing gravity, studying dense matter, and probing gravitational waves. A key indirect tracer of this population is the Fermi GeV excess (FGE), an unresolved gamma-ray signal possibly originating from thousands of faint MSPs. However, the lack of direct detections has limited our ability to test this hypothesis.\n The MeerKAT Galactic Bulge Survey (MGBS) is the most sensitive pulsar search yet of this region, targeting the bulge MSP population. Early results from MGBS have already revealed several promising MSP candidates. We propose to use Murriyang to conduct targeted follow-up observations of three of the most compelling candidates from MGBS. Our goals are to confirm the pulsations, refine key parameters such as spectral indices and orbital characteristics, and strengthen their association with the bulge.\n Confirming even a handful of bulge MSPs would have wide-reaching impact: constraining the origin of the FGE, testing dark matter interpretations, refining models of Galactic structure, and improving predictions for low-frequency gravitational wave backgrounds. This proposal is a critical next step toward establishing a long-sought bulge MSP population and unlocking new physics from the inner Galaxy.

理论上，银河核球（Galactic bulge）中存在大量毫秒脉冲星（millisecond pulsars, MSPs），但受银心（Galactic center）附近强烈的星际散射、色散与背景噪声影响，这类天体的直接探测一直受到严重阻碍。若能确认这类毫秒脉冲星的存在，它们将成为检验引力理论、研究致密物质以及探测引力波的强有力工具。该脉冲星群体的关键间接示踪物为费米GeV超出（Fermi GeV excess, FGE）——这一未解析的伽马射线信号可能源自数千颗微弱的毫秒脉冲星。但由于尚未获得直接探测结果，我们对这一假说的验证工作始终受限。
MeerKAT银河核球巡天（MeerKAT Galactic Bulge Survey, MGBS）是目前针对该区域灵敏度最高的脉冲星搜寻项目，其核心目标为银河核球内的毫秒脉冲星群体。该巡天项目的早期结果已发现多颗极具研究价值的毫秒脉冲星候选体。本研究拟利用Murriyang望远镜对MeerKAT银河核球巡天中3个最具说服力的候选体开展靶向后续观测，本次观测的目标为确认其脉冲信号、精确修正谱指数（spectral indices）与轨道特征（orbital characteristics）等关键参数，并强化这些候选体与银河核球的关联性。
即便仅确认数颗银河核球内的毫秒脉冲星，也将产生广泛影响：可限制费米GeV超出的起源、检验暗物质（dark matter）相关解释、优化银河结构模型，并改进低频引力波背景（low-frequency gravitational wave backgrounds）的预测结果。本申请是确立长期以来备受关注的银河核球毫秒脉冲星群体、并从银河中心区域解锁全新物理研究方向的关键下一步。