Radio Transients and Variables in the Tenth Deeper, Wider, Faster Observing Run

TL;DR

This paper reports on a multi-telescope observational campaign targeting transient radio sources, identifying eight variable sources including a slow-rotating ultra-cool dwarf, and demonstrating the effectiveness of image-domain searches in radio transient detection.

Contribution

First comprehensive radio transient survey during the DWF 10th run, identifying new variable sources and demonstrating the detection of a slow-rotating ultra-cool dwarf via radio observations.

Findings

Detected eight variable radio sources, including a previously uncatalogued source.

Identified pulses from SCR J1845-6357 with a 14.2-hour period, the slowest known radio-loud ultra-cool dwarf.

Validated the effectiveness of image-domain searches for transient and variable radio sources.

Abstract

The Deeper, Wider, Faster (DWF) program coordinates observations with telescopes across the electromagnetic spectrum, searching for transients on timescales of milliseconds to days. The tenth DWF observing run was carried out in near real-time during September 2021 and consisted of six consecutive days of observations of the NGC 6744 galaxy group and a field containing the repeating fast radio burst FRB190711 with the Australian Square Kilometre Array Pathfinder, the Dark Energy Camera, the Hard X-ray Modulation Telescope and the Parkes 64m "Murriyang" radio telescope. In this work we present the results of an image-domain search for transient, variable and circularly polarised sources carried out with ASKAP using data from the observing run, along with test observations prior to the run and follow-up observations carried out during and after the run. We identified eight variable radio sources, consisting of one pulsar, six stellar systems (five of which exhibit circularly polarised emission) and one previously uncatalogued source. Of particular interest is the detection of pulses from the ultra-cool dwarf SCR J1845-6357 with a period of $14.2\pm 0.3$ h, in good agreement with the known optical rotation period, making this the slowest rotating radio-loud ultra-cool dwarf discovered.