A Census of Southern Pulsars at 185 MHz

TL;DR

This paper reports a low-frequency pulsar survey using the MWA, detecting 50 pulsars including six millisecond pulsars, and forecasts the potential of SKA-Low to detect around 9400 pulsars.

Contribution

It introduces a new wide-field pipeline for pulsar detection at 185 MHz and provides the first census of southern pulsars at this frequency.

Findings

Detected 50 pulsars, including 6 millisecond pulsars.

Presented lowest-frequency detections for 10 pulsars.

Forecasted SKA-Low could detect around 9400 pulsars.

Abstract

The Murchison Widefield Array (MWA), and its recently-developed Voltage Capture System (VCS), facilitates extending the low-frequency range of pulsar observations at high-time and -frequency resolution in the Southern Hemisphere, providing further information about pulsars and the ISM. We present the results of an initial time-resolved census of known pulsars using the MWA. To significantly reduce the processing load, we incoherently sum the detected powers from the 128 MWA tiles, which yields ~10% of the attainable sensitivity of the coherent sum. This preserves the large field-of-view (~450 deg2 at 185 MHz), allowing multiple pulsars to be observed simultaneously. We developed a WIde-field Pulsar Pipeline (WIPP) that processes the data from each observation and automatically folds every known pulsar located within the beam. We have detected 50 pulsars to date, 6 of which are millisecond pulsars. This is consistent with our expectation, given the telescope sensitivity and the sky coverage of the processed data (~17,000 deg2). For ten pulsars, we present the lowest-frequency detections published. For a subset of the pulsars, we present multi-frequency pulse profiles by combining our data with published profiles from other telescopes. Since the MWA is a low-frequency precursor to the Square Kilometre Array (SKA), we use our census results to forecast that a survey using Phase 1 of SKA-Low (SKA1-Low) can potentially detect around 9400 pulsars.