Understanding sub-arcsecond scale radio sources and space weather with the SKA-Low using interplanetary scintillation

Abstract

Continuum surveys with SKA-Low will provide excellent spectral information for detected objects. However, the angular resolution it provides cannot clearly distinguish between extended radio galaxies and their sub-arcsecond scale counterparts. We have previously used an interplanetary scintillation (IPS) technique with wide field-of-view instruments (the MWA and ASKAP) to detect and study $<$0.3\arcsec\ objects. The ability to identify hundreds of compact sources from large areas of the sky using $<$5 minutes of data, and associated low computational cost makes widefield IPS a very efficient approach to identify sub-arcsecond scale objects at low radio frequencies. We aim to utilise SKA-Low's flexibility in data capture, frequency coverage and high sensitivity to develop widefield IPS technique with SKA-Low, enabling the identification of compact radio sources at angular scales more than an order of magnitude smaller than that achieved by SKA-Low's longest baselines. This capability will facilitate studies of compact source populations (e.g., AGN cores), their relationship to extended radio galaxies, AGN contributions in star-forming galaxies, identify candidates for pulsars and HI absorption, and provide a network of calibrators for direction-dependent ionospheric calibration for SKA-Low. Additionally, ground-based IPS observations are one of the very few remote sensing techniques to probe the Heliosphere which will enable SKA-Low to provide unique insights into the solar wind. Here, we present recent developments in the field of compact sources at low frequencies, their synergies with other fields of astronomy and space weather, and outline the technical developments and approaches that are necessary with the SKA-Low to realise these studies.