Parkes observations for project P895 semester 2019OCTS_05

Since the year 2005, the Parkes Pulsar Timing Array (PPTA) project has been placing ever more stringent constraints on the amplitude of a gravitational wave background signal. Such upper bounds on the amplitude of the gravitational wave signal are currently dominated by a single pulsar: PSR J1909-3744. The upper bound with this pulsar alone already cuts into the range of tenable theoretical models. Further reducing the amplitude bound (by continued regular observations of this pulsar) will significantly narrow that range. The first evidence of gravitational waves in the pulsar data are likely to be observed in the timing for PSR J1909-3744, but with only a single pulsar we will not be able to make an unambiguous detection. However, knowledge of the likely signal strength (derived from this pulsar) will help to optimise the observing strategy for the detection of the gravitational wave signals with existing or future pulsar timing arrays.

自2005年以来，帕克斯脉冲星计时阵列（Parkes Pulsar Timing Array, PPTA）项目一直在对引力波背景信号的振幅施加愈发严苛的限制。当前，该引力波信号振幅的上限值主要由单颗脉冲星PSR J1909-3744主导。仅依靠该脉冲星得到的振幅上限，已经压缩了可行理论模型的取值范围。通过持续对该脉冲星进行常规观测以进一步降低振幅上限，将显著缩小这一理论模型的可选范围。脉冲星数据中引力波的首个观测证据，很可能会在PSR J1909-3744的计时观测中被捕捉到，但仅依靠单颗脉冲星，我们无法完成明确的引力波探测。不过，基于该脉冲星推导得到的潜在信号强度信息，将有助于优化利用现有或未来脉冲星计时阵列探测引力波信号的观测策略。