Long-term project observations for project P456 semester 2025OCTS_03

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.

帕克斯脉冲星计时阵列（Parkes Pulsar Timing Array, PPTA）项目拥有三大核心目标：(a) 探测来自天文天体的引力波；(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——我们的数据集（及其他相关数据集）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。我们正与国际学界携手，全力验证该信号的真实性，并探明其天体物理起源。本申请旨在维持我们在该领域的领先地位。这是一项持续性研究申请，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这类信号。至少在平方千米阵列（Square Kilometre Array, SKA）的第一阶段项目能够提升我们的观测灵敏度与观测节奏之前，帕克斯望远镜的持续观测仍将具备重要科学价值。即便引力波背景被成功探测，持续的观测仍将进一步厘清该背景的起源并识别出单个引力波源，从而推动引力波天文学这一新兴领域的发展。