The study of multi-frequency scattering of 10 radio pulsars

Abstract

We present the results of the multi-frequency scatter time measurements for 10 radio pulsars that were relatively less studied in this regard. The observations were performed using the Giant Metrewave Radio Telescope at the observing frequencies of 150, 235, 325, 610 and 1060 MHz. The data we collected, in conjunction with the results from other frequencies published earlier, allowed us to estimate the scatter time frequency scaling indices for eight of these sources. For PSR J1852-0635, it became evident that its profile undergoes a strong evolution with frequency, which makes the scatter time measurements difficult to perform, and for PSR J1835-1020 we were able to obtain reliable pulse broadening estimates at only two frequencies. We used the eight frequency scaling indices to estimate both: the electron density fluctuation strengths along the respective lines of sight and the standardized amount of scattering at the frequency of 1 GHz. Combining the new data with the results published earlier by Lewandowski et al., we revisited the scaling index versus the dispersion measure (DM) relation, and similarly to some of the earlier studies, we show that the average value of the scaling index deviates from the theoretical predictions for large-DM pulsars; however, it reaches the magnitude claimed by Löhmer et al. only for pulsars with very largeDMs (> 650 pc cm-3).We also investigated the dependence of the scattering strength indicators on the pulsar distance, DM and the position of the source in the Milky Way Galaxy.