Scattering Delay Mitigation in High Accuracy Pulsar Timing: Cyclic Spectroscopy Techniques

TL;DR

This paper compares traditional autocorrelation methods and cyclic spectroscopy for estimating interstellar scattering delays in pulsar timing, demonstrating cyclic spectroscopy's superior accuracy in high-quality data.

Contribution

The study introduces cyclic spectroscopy as a more accurate technique for scattering delay estimation in pulsar timing compared to traditional autocorrelation methods.

Findings

Cyclic spectroscopy outperforms autocorrelation fitting at high S/N.

Autocorrelation estimators exhibit large variance despite high S/N.

Both methods are effective, but cyclic spectroscopy provides more precise delay recovery.

Abstract

We simulate scattering delays from the interstellar medium to examine the effectiveness of three estimators in recovering these delays in pulsar timing data. Two of these estimators use the more traditional process of fitting autocorrelation functions to pulsar dynamic spectra to extract scintillation bandwidths, while the third estimator uses the newer technique of cyclic spectroscopy on baseband pulsar data to recover the interstellar medium's impulse response function. We find that either fitting a Lorentzian or Gaussian distribution to an autocorrelation function or recovering the impulse response function from the cyclic spectrum are, on average, accurate in recovering scattering delays, although autocorrelation function estimators have a large variance, even at high signal-to-noise ratio (S/N). We find that, given sufficient S/N, cyclic spectroscopy is more accurate than both Gaussian and Lorentzian fitting for recovering scattering delays at specific epochs, suggesting that cyclic spectroscopy is a superior method for scattering estimation in high quality data.