Prospects for Discovering Pulsars in Future Continuum Surveys Using Variance Imaging

TL;DR

Variance imaging in future radio continuum surveys can significantly increase pulsar discoveries, especially for millisecond pulsars and those in binary systems, complementing traditional periodic signal searches.

Contribution

This paper predicts the number of pulsars detectable via variance imaging in upcoming continuum surveys, demonstrating its potential to enhance pulsar detection capabilities.

Findings

ASKAP EMU survey can find ~30 normal and ~40 MSPs beyond current known.

SKA-MID all-sky survey can discover ~140 normal and ~110 MSPs.

Variance imaging is more sensitive to pulsars with large duty cycles and certain dispersion measures.

Abstract

In Dai et al. (2016) we developed a formalism for computing variance images from standard, interferometric radio images containing time and frequency information. Variance imaging with future radio continuum surveys allows us to identify radio pulsars and serves as a complement to conventional pulsar searches which are most sensitive to strictly periodic signals. Here, we carry out simulations to predict the number of pulsars that we can uncover with variance imaging on future continuum surveys. We show that the Australian SKA Pathfinder (ASKAP) Evolutionary Map of the Universe (EMU) survey can find $\sim30$ normal pulsars and $\sim40$ millisecond pulsars (MSPs) over and above the number known today, and similarly an all-sky continuum survey with SKA-MID can discover $\sim140$ normal pulsars and $\sim110$ MSPs with this technique. Variance imaging with EMU and SKA-MID will detect pulsars with large duty cycles and is therefore a potential tool for finding MSPs and pulsars in relativistic binary systems. Compared with current pulsar surveys at high Galactic latitudes in the southern hemisphere, variance imaging with EMU and SKA-MID will be more sensitive, and will enable detection of pulsars with dispersion measures between $\sim10$ and 100 cm$^{-3}$ pc.