A new method for short duration transient detection in radio images: Searching for transient sources in MeerKAT data of NGC 5068

TL;DR

This paper introduces an efficient method for detecting short-duration radio transients in large datasets, applied to MeerKAT data of NGC 5068, setting new limits on transient surface densities without confirming any new transient sources.

Contribution

It develops a rapid wide-field imaging strategy and filtering methods for short-duration transient detection in radio data, demonstrating their effectiveness on MeerKAT observations.

Findings

No transient candidates detected on 8s, 128s, and 1h scales.

Set competitive upper limits on transient surface densities.

Identified one possible stellar flare candidate, requiring further observation.

Abstract

Transient surveys are a vital tool in exploring the dynamic universe, with radio transients acting as beacons for explosive and highly energetic astrophysical phenomena. However, performing commensal transient surveys using radio imaging can require a significant amount of computing power, data storage and time. With the instrumentation available to us, and with new and exciting radio interferometers in development, it is essential that we develop efficient methods to probe the radio transient sky. In this paper, we present results from an commensal short duration transient survey, on time scales of 8 seconds, 128 seconds and 1 hour, using data from the MeerKAT radio telescope. The dataset used was obtained as part of a galaxy observing campaign, and we focus on the field of NGC 5068. We present a quick, wide field imaging strategy to enable fast imaging of large datasets, and develop methods to efficiently filter detected transient candidates. No transient candidates were identified on the time scales of 8 seconds, 128 seconds and 1 hour, leading to competitive limits on the transient surface densities of $6.7{\times}10^{-5}$ deg$^{-1}$, $1.1{\times}10^{-3}$ deg$^{-1}$, and $3.2{\times}10^{-2}$ deg$^{-1}$ at sensitivities of 56.4 mJy, 19.2 mJy, and 3.9 mJy for the respective time scales. We find one possible candidate that could be associated with a stellar flare, that was rejected due to strict image quality control. Further short time-scale radio observations of this candidate could give definite results to its origin.