Scintillation Bandwidth Measurements from 23 Pulsars from the AO327 Survey

TL;DR

This study measures scintillation bandwidths for 23 pulsars using AO327 survey data, revealing discrepancies with galactic models and variability over time, which are crucial for gravitational wave detection efforts.

Contribution

First measurements of scintillation bandwidths for six pulsars without prior data, and analysis of their variability and model discrepancies using large archival datasets.

Findings

Most measurements exceed model predictions

Gaussian fits align better with models than Lorentzian

Significant variability observed in literature values over time

Abstract

A pulsar's scintillation bandwidth is inversely proportional to the scattering delay, making accurate measurements of scintillation bandwidth critical to characterize unmitigated delays in efforts to measure low-frequency gravitational waves with pulsar timing arrays. In this pilot work, we searched for a subset of known pulsars within $\sim$97% of the data taken with the PUPPI instrument for the AO327 survey with the Arecibo telescope, attempting to measure the scintillation bandwidths in the dataset by fitting to the 2D autocorrelation function of their dynamic spectra. We successfully measured 38 bandwidths from 23 pulsars (six without prior literature values), finding that: almost all of the measurements are larger than the predictions from NE2001 and YMW16 (two popular galactic models); NE2001 is more consistent with our measurements than YMW16; Gaussian fits to the bandwidth are more consistent with both electron density models than Lorentzian ones; and for the 17 pulsars with prior literature values, the measurements between various sources often vary by factors of a few. The success of Gaussian fits may be due to the use of Gaussian fits to train models in previous work. The variance of literature values over time could relate to the scaling factor used to compare measurements, but also seems consistent with time-varying interstellar medium parameters. This work can be extended to the rest of AO327 to further investigate these trends, highlighting the continuing importance of large archival datasets for projects beyond their initial conception.