Parkes observations for project P456 semester 2018OCTS_40

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. The PPTA is the oldest of three international pulsar timing groups. We have the smallest telescope and the smallest group, but the best measurements and the best results. Our bound on the strength of the incoherent gravitational wave background is the only bound which significantly constrains theoretical models. We have maintained our leading position because: we have the southern sky; we have a small but well-focussed group; we have the best-calibrated receivers; and we have been able to observe with an almost regular cadence of 15 to 20 days at three different wavelengths. With this proposal we aim to maintain our pre-eminent position in the field.\r\n\r\nUnlike most observing proposals, this is a continuing proposal for which the observations will continue to improve bounds on ultra-low-frequency gravitational waves until they are finally detected. 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 we will want to continue observations in support of the nascent field of gravitational wave astronomy!

帕克斯脉冲星计时阵列（Parkes Pulsar Timing Array, PPTA）项目具备三大核心目标：（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。PPTA是三大国际脉冲星计时研究组中历史最悠久的团队。我们虽拥有规模最小的望远镜与最小的研究团队，却取得了最优的测量结果与最出色的科研成果。我们针对非相干引力波背景强度给出的约束条件，是目前唯一能显著约束相关理论模型的约束结果。我们能够长期保持领域领先地位的原因在于：我们拥有南天区的独特观测视野；我们拥有一支精干且目标高度聚焦的研究团队；我们配备了校准精度最高的接收系统；并且我们能够以15至20天近乎固定的观测频次，在三个不同波段开展观测。通过本次提案，我们旨在巩固自身在该领域的领先地位。
与多数观测提案不同，本次提案属于持续性观测项目，相关观测将持续优化超低频率引力波的约束精度，直至最终实现该信号的直接探测。帕克斯（Parkes）望远镜的持续观测至少仍将具备科学价值，直至平方千米阵列（Square Kilometre Array, SKA）的第一阶段项目能够在灵敏度与观测频次上超越我们。即便在引力波背景被成功探测之后，我们仍将持续开展观测，以支持这一新兴的引力波天文学领域的发展！