精确脉冲星定时观测中折射传播效应的模拟和减轻
Modelling and mitigating refractive propagation effects in precision pulsar timing observations
摘要：
为了获得最精确的无线电脉冲到达时间，有必要校正或减轻无线电波通过温暖和电离的星际介质传播的影响。我们研究了与大规模电子密度变化相关的传播效应的强度和用于估计无限频率到达时间的方法。使用模拟的二维相位变化屏幕，我们评估的强度和非平稳性的定时扰动与大规模的密度变化。我们确定额外的贡献，到达时间是随机的射频和时间，因此不适合校正只使用到达时间。我们将此归因于传播的无线电波的轨迹的频率依赖性。我们发现，这限制了低频（米波长）观测的有效性。将低频脉冲星观测纳入精确计时活动对于具有较大色散措施的脉冲星来说越来越成问题。
英文摘要：
To obtain the most accurate pulse arrival times from radio pulsars, it is necessary to correct or mitigate the effects of the propagation of radio waves through the warm and ionised interstellar medium. We examine both the strength of propagation effects associated with large-scale electron-density variations and the methodology used to estimate infinite-frequency arrival times. Using simulations of two-dimensional phase-varying screens, we assess the strength and non-stationarity of timing perturbations associated with large-scale density variations. We identify additional contributions to arrival times that are stochastic in both radio frequency and time and therefore not amenable to correction solely using times of arrival. We attribute this to the frequency dependence of the trajectories of the propagating radio waves. We find that this limits the efficacy of low-frequency (metre-wavelength) observations. Incorporating low-frequency pulsar observations into precision timing campaigns is increasingly problematic for pulsars with larger dispersion measures.
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