Characterizing Pulsars Detected in the Rapid ASKAP Continuum Survey

TL;DR

This study detects 661 known pulsars with ASKAP at 888 MHz, analyzes their spectral indices and polarization, and finds that many pulsars deviate from simple spectral models, providing new insights into pulsar emission properties.

Contribution

First comprehensive analysis of pulsar spectra and polarization using ASKAP data, revealing deviations from simple models and characterizing their emission properties.

Findings

Mean spectral index is -1.78 +/- 0.6.

Up to 40% of pulsars deviate from a simple power law.

Mean polarization fraction is ~10%.

Abstract

We present the detection of 661 known pulsars observed with the Australian SKA Pathfinder (ASKAP) telescope at 888 MHz as a part of the Rapid ASKAP Continuum Survey (RACS). Detections were made through astrometric coincidence and we estimate the false alarm rate of our sample to be ~0.5%. Using archival data at 400 and 1400 MHz, we estimate the power law spectral indices for the pulsars in our sample and find that the mean spectral index is -1.78 +/- 0.6. However, we also find that a single power law is inadequate to model all the observed spectra. With the addition of the flux densities between 150 MHz and 3 GHz from various imaging surveys, we find that up to 40% of our sample shows deviations from a simple power law model. Using Stokes V measurements from the RACS data, we measured the circular polarization fraction for 9% of our sample and find that the mean polarization fraction is ~10% (consistent between detections and upper limits). Using the dispersion measure (DM) derived distance we estimate the pseudo luminosity of the pulsars and do not find any strong evidence for a correlation with the pulsars' intrinsic properties.