Clarify the origin of residual central emission in Abell 3378 (PSZ2 G241.79−24.01) after filtering

Ascertain whether the residual diffuse radio emission observed at the centre of Abell 3378 (PSZ2 G241.79−24.01) following uv-plane filtering and removal of the bright point source PKS 0604−352 represents genuine cluster synchrotron emission or instead arises from residual imaging artefacts induced by the bright source, in order to validate detections of low-surface-brightness central emission in clusters with bright cores.

Background

The paper compares uv-plane subtraction and image-based angular-scale filtering to isolate diffuse, low-surface-brightness radio emission in galaxy clusters. In clusters with very bright central point sources, both approaches can be compromised by artefacts.

Abell 3378 (PSZ2 G241.79−24.01) hosts the bright source PKS 0604−352 at its centre. After image-based filtering, artefacts around the bright source produce negative regions, and after uv-plane filtering and point-source removal, residual central emission persists. The authors note that it is unclear whether this residual is genuine diffuse cluster emission or an artefact.

Resolving this uncertainty is important for confirming radio halos or other diffuse central components in clusters that contain bright core sources, and for assessing the reliability of automated filtering approaches planned for the EMU survey.