Parkes observations for project P1064 semester 2020APRS_01

The propagation of pulsar signal through the interstellar medium is affected by the fluctuations in the electron density in the line of sight from the pulsar to the observer. This is a frequency dependent phenomenon and will produce brightness variations (scintillation) and also broadening of the otherwise narrow pulse (scatter-broadening). The effect of these two are measurable at different frequencies due to their strong dependence on frequency, viz., broadening will be evident at lower radio frequencies and scintillation will be clearly resolved at higher frequencies. With this proposal, we aim to study the evolution of scatter-broadening and scintillation properties of 137 pulsars with the UWL receiver, and verify their relationship with each other. With this experiment, we aim at testing some of the fundamental theories of ionised interstellar medium. This large sample will also help in improving the understanding of the turbulence characteristics in the inner Galaxy. We request a total of 149 hours for this project.

脉冲星（pulsar）信号在穿过星际介质（interstellar medium）的过程中，会受到从脉冲星至观测者视线方向上电子密度涨落的影响。该现象具有频率依赖性，可引发亮度变化（闪烁，scintillation），同时还会使原本窄的脉冲产生展宽效应（散射展宽，scatter-broadening）。由于两种效应均与频率存在极强的依赖关系，因此可在不同频段分别观测到其影响：散射展宽在低频射电波段表现更为显著，而闪烁则可在高频波段被清晰分辨。
本项目提案旨在借助UWL接收机（UWL receiver），对137颗脉冲星的散射展宽与闪烁特性的演化规律展开研究，并验证二者的内在关联。通过本次实验，我们将对电离星际介质（ionised interstellar medium）的若干基础理论进行检验。本次研究采用的大样本量有助于加深我们对银河系内区（inner Galaxy）湍流特性的认知。本项目总计申请观测时长149小时。