Commensal searches for radio transients variables in the data from Mhongoose Large Survey Project

Abstract

The MeerKAT radio telescope in South Africa, a precursor to the mid-frequency component of the Square Kilometre Array (SKA1-Mid), offers exceptional sensitivity and a wide field of view, making it ideal for exploring time-domain radio astronomy. This dissertation presents the use of MeerKAT images from three different fields of the MHONGOOSE Large Survey Project (LSP) to identify radio transient and variable sources. Each of these three fields consists of 10 different epochs spanning time scales of order one month to over 1 year. The MHONGOOSE survey operates at a central observing frequency of 1.28 GHz. I made use of South African Radio Astronomy Observatory (SARAO) Science Data Processing (SDP) images of the MHONGOOSE observations, with source detection and variability analysis conducted via the Transient Pipeline (TraP) software on the Inter-University Institute for Data Intensive Astronomy (IDIA) cloud. The light curves generated by TraP enabled the calculation of variability parameters: the reduced weighted chi-square (χ2) of a fit that assumes constant brightness represented by the symbol (ην) and the coefficient of variation (Vν). Analysis of ten epochs across the fields of NGC 1566, NGC 5068, and NGC 1371 led to the identification of 31 variable sources. All variable sources identified in this study are associated with known objects listed in existing multi-wavelength catalogues and are classified as active galactic nuclei (AGNs). One radio transient was found in the NGC 1566 field “SRC76717”, which is associated with a nearby flaring M dwarf located at a distance of 48 pc (Doyle et al., 2019).