Discovery of a steep-spectrum low-luminosity pulsar with the Murchison Widefield Array

TL;DR

This paper reports the discovery of a new low-luminosity, steep-spectrum pulsar using the Murchison Widefield Array, highlighting the potential for uncovering more such faint pulsars with low-frequency radio surveys.

Contribution

First discovery of a pulsar with the MWA, demonstrating the effectiveness of low-frequency surveys in finding faint, steep-spectrum pulsars and revealing their variability and polarization properties.

Findings

Pulsar has a steep spectrum with S(ν) ∝ ν^{-2.0 ± 0.2}

Flux density varies by a factor of 5-6 over weeks to months

Detected polarization properties in MWA and Parkes data

Abstract

We report the discovery of the first new pulsar with the Murchison Widefield Array (MWA), PSR J0036$-$1033, a long-period (0.9 s) nonrecycled pulsar with a dispersion measure (DM) of 23.1 ${\rm pc\,cm^{-3}}$. It was found after processing only a small fraction ($\sim$1%) of data from an ongoing all-sky pulsar survey. Follow-up observations have been made with the MWA, the upgraded Giant Metrewave Radio Telescope (uGMRT), and the Parkes 64 m telescopes, spanning a frequency range from $\sim$150 MHz to 4 GHz. The pulsar is faint, with an estimated flux density ($S$) of $\sim$1 mJy at 400 MHz and a spectrum $S(\nu)\,\propto\,\nu^{-2.0 \pm 0.2}$, where $\nu$ is frequency. The DM-derived distance implies that it is also a low-luminosity source ($\sim$ 0.1 ${\rm mJy\,kpc^2}$ at 1400 MHz). The analysis of archival MWA observations reveals that the pulsar's mean flux density varies by up to a factor of $\sim$5-6 on timescales of several weeks to months. By combining MWA and uGMRT data, the pulsar position was determined to arcsecond precision. We also report on polarization properties detected in the MWA and Parkes bands. The pulsar's nondetection in previous pulsar and continuum imaging surveys, the observed high variability, and its detection in a small fraction of the survey data searched to date, all hint at a larger population of pulsars that await discovery in the southern hemisphere, with the MWA and the future low-frequency Square Kilometre Array.