A Simultaneous Dual-Frequency Scintillation Arc Survey of Six Bright Canonical Pulsars Using the Upgraded Giant Metrewave Radio Telescope

Jacob E. Turner, Bhal Chandra Joshi, Maura A. McLaughlin, Daniel R. Stinebring

Published 2023-01-12Version 1

We use the Upgraded Giant Metrewave Radio Telescope to measure scintillation arc properties in six bright canonical pulsars with simultaneous dual frequency coverage. These observations at frequencies from 300 to 750 MHz allowed for detailed analysis of arc evolution across frequency and epoch. We perform more robust determinations of arc curvature and scattering delay frequency-dependence than allowed by single-frequency-band-per-epoch measurements, which we find to agree with theory and previous literature. We report the discovery of a strong correlation between arc asymmetry and arc curvature, potentially indicating a link between scattering screen distance and refraction strength or the effect of asymmetric distribution of scattering material on a scattering screen. The inclusion of a 155 minute observation allowed us to resolve the scale of scintillation variations on short timescales, which we find to be directly tied to the amount of ISM sampled over the observation. Some of our pulsars showed either consistent or emerging asymmetries in arc curvature, indicating instances of refraction across their lines of sight. The presence of significant features in various pulsars, such as multiple scintillation arcs in PSR J1136+1551 and flat arclets in PSR J1509+5531, that have been found in previous works, were also sufficiently detected. Possible evidence for a timescale over which a given scattering screen dominates signal propagation was found by tracking visible scintillation arcs in each epoch in PSR J1136+1551. The interesting pulsar science accomplished with this upgraded telescope shows strong promise for important future work in pulsar astronomy.