Detecting Pulsars with Interstellar Scintillation in Variance Images

TL;DR

This paper presents a novel method for detecting pulsars using variance images from radio telescope data, which can efficiently identify pulsars by exploiting their interstellar scintillation properties without high time resolution searches.

Contribution

The study introduces a variance image technique for pulsar detection that enhances sensitivity to scintillating pulsars in large-scale radio surveys, optimizing detection by adjusting time and frequency resolution.

Findings

Variance images are most sensitive to pulsars with specific scintillation time-scales and bandwidths.

High time and frequency resolution are crucial for maximizing pulsar detection sensitivity.

The method successfully detects pulsars in Murchison Widefield Array data.

Abstract

Pulsars are the only cosmic radio sources known to be sufficiently compact to show diffractive interstellar scintillations. Images of the variance of radio signals in both time and frequency can be used to detect pulsars in large-scale continuum surveys using the next generation of synthesis radio telescopes. This technique allows a search over the full field of view while avoiding the need for expensive pixel-by-pixel high time resolution searches. We investigate the sensitivity of detecting pulsars in variance images. We show that variance images are most sensitive to pulsars whose scintillation time-scales and bandwidths are close to the subintegration time and channel bandwidth. Therefore, in order to maximise the detection of pulsars for a given radio continuum survey, it is essential to retain a high time and frequency resolution, allowing us to make variance images sensitive to pulsars with different scintillation properties. We demonstrate the technique with Murchision Widefield Array data and show that variance images can indeed lead to the detection of pulsars by distinguishing them from other radio sources.