Long-term project observations for project P456 semester 2025APRS_10

The Parkes Pulsar Timing Array (PPTA) project has three primary goals: (a) detection of gravitational waves from astronomical sources, (b) establishment of a pulsar timescale, and (c) improvement of our understanding of Solar-system dynamics. We are now in an exciting regime where a signal detected in our (and other data sets) has the form expected for a gravitational wave background. We, along with the international community, are now working hard to either confirm or deny this result, and to determine the astrophysical origin of this signal. With this proposal, we aim to maintain our pre-eminent position in the field. This is a continuing proposal for which observations of millisecond pulsars (MSPs) will continue to improve bounds on ultra-low-frequency gravitational waves until they are detected with confidence. Continued Parkes observations will remain valuable at least until the first stage of the SKA is able to improve on our sensitivity and observing cadence. Even after the gravitational wave background is detected, continued observations will resolve the background origin and individual sources will be identified; advancing the nascent field of gravitational wave astronomy.

Parkes脉冲星计时阵列（Parkes Pulsar Timing Array, PPTA）项目设有三大核心目标：（a）探测来自天文源的引力波，（b）建立脉冲星时标系统，（c）深化对太阳系动力学的认知。当前我们正处于令人振奋的研究阶段——我们（及其他数据集）中探测到的信号，其形态完全符合引力波背景的理论预期特征。目前我们正与国际学界通力协作，全力验证该信号的真实性，并明确其天体物理起源。通过本申请，我们旨在维持本领域的领先地位。本项目为持续性申请，毫秒脉冲星（millisecond pulsars, MSPs）的观测将持续收紧超低频引力波的探测约束，直至我们能够确凿地探测到该信号。帕克斯望远镜的持续观测至少将保持其科学价值，直至平方千米阵（Square Kilometre Array, SKA）的第一阶段项目能够在灵敏度与观测节奏上实现超越。即便引力波背景被成功探测，后续持续观测仍将解析该背景的起源，并甄别出单个引力波源；这将推动尚处于起步阶段的引力波天文学领域实现长足发展。