Parkes observations for project P897 semester 2017APRS

Modulation of pulse times of arrival (TOAs) from pulsars often heralds excitement: planetary companions, neutron star free precession, and the poorly understood but crucially important process of magnetospheric state switching can all produce quasi-periodic TOA modulation. In a sample of 150 young pulsars, we have detected periodic modulation in six pulsars. We propose to obtain multi-epoch, deep, well-calibrated 10 cm pulse profiles to search for profile variability, particularly variability correlated with TOA modulation. The absence of such variation may lend credence to a planet interpretation, while detection will help characterize the magnetospheric states and determine if free precession plays a role. Because the pulsars are largely southern sky objects, and because the 10cm band is largely free from RFI and scattering, Parkes is uniquely capable to deliver this science.

脉冲星脉冲到达时间（TOAs）的调制现象，往往预示着多项极具科研价值的天体物理现象：行星伴星、中子星自由进动，以及虽尚未完全明晰却至关重要的磁层状态转换过程，均可引发准周期TOA调制。在150颗年轻脉冲星构成的观测样本中，我们已在6颗脉冲星中探测到周期性调制信号。
本研究计划获取多历元、深曝光且经高精度校准的10 cm波段脉冲轮廓，以搜寻脉冲轮廓的变化特征，尤其是与TOA调制相关的变化信号。若未观测到此类轮廓变化，将为行星伴星的成因解释提供佐证；若探测到变化，则有助于表征磁层状态，并可判断自由进动是否在其中发挥作用。
由于这批脉冲星大多位于南天天区，且10 cm波段几乎不受射频干扰（Radio Frequency Interference，RFI）与星际散射的影响，帕克斯（Parkes）望远镜是开展此项科研工作的唯一最优平台。