Discovery of a Steep-spectrum Low-luminosity Pulsar with the Murchison Widefield Array

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 pc cm−3. It was found after processing only a small fraction (∼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 ∼150 MHz to 4 GHz. The pulsar is faint, with an estimated flux density (S) of ∼1 mJy at 400 MHz and a spectrum , where ν is frequency. The DM-derived distance implies that it is also a low-luminosity source (∼0.1 mJy kpc2 at 1400 MHz). The analysis of archival MWA observations reveals that the pulsar’s mean flux density varies by up to a factor of ∼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.

MWA tied-array processing IV: A multi-pixel beamformer for pulsar surveys and ionospheric corrected localisation

“…The improved efficiency of the multi-pixel beamformer makes large scale processing such as pulsar surveys and candidate localisation (Swainston et al 2021) computationally feasible. Unlike other telescopes, the MWA VCS can beamform in post-processing and create a grid of pointings to estimate the position of the source without the need for re-observation.…”

Independent Discovery of a Nulling Pulsar with Unusual Subpulse Drifting Properties with the Murchison Widefield Array

“…A full description of the survey parameters and observational setup will be presented in an upcoming publication (N. D. R. Bhat et al 2022, in preparation). Many details are also described in the paper reporting the first SMART pulsar discovery (Swainston et al 2021), for which the setup was identical, but the essential details are summarized here. The VCS delivers Nyquist-sampled dual-polarization voltages for 128 MWA tiles (4 × 4 cross-dipoles) at a rate of 100 μs and an instantaneous bandwidth of 30.72 MHz, consisting of 3072 × 10 kHz individual channels.…”

“…At present, ∼70% of the data have been collected, with the initial, first-pass ("shallow") processing being limited to the first 10 minutes (out of the full 80 minutes) of each observation. This strategy is beginning to pay off; the discovery of PSR J0036−1033, a low-luminosity, high Galactic latitude pulsar (b ≈ −73°), was reported in Swainston et al (2021).…”

High time resolution search for prompt radio emission from the long GRB 210419A with the Murchison Widefield Array

“…The de-dispersion search was performed using the software package (Ransom 2001). As the MWA is generally less affected by radio-frequency interference (RFI) when compared to other telescopes traditionally used for high-time resolution analysis, we did not perform any RFI removal that is often used at higher observing frequencies (see procedures outlined in Swainston et al 2021). Nevertheless, any spurious events caused by RFI can be identified from the final candidates by visual inspection.…”