Next-generation radio array to map faint plasma of the cosmic web
The upcoming Square Kilometre Array will enable detailed radio observations of the low-density plasma in galaxy filaments and cluster outskirts, building on recent detections made with LOFAR, uGMRT and MeerKAT.
Astronomers plan to use the Square Kilometre Array (SKA) to image the diffuse plasma that fills the filaments and peripheral regions of galaxy clusters, a component of the large-scale structure known as the cosmic web. Simulations based on the standard Lambda-CDM model predict that hot, thin gas occupies both the dense nodes (clusters) and the connecting strands, but direct observations have been limited because the emission is extremely faint.
Recent observations with highly sensitive radio facilities such as LOFAR in Europe, the upgraded GMRT in India and MeerKAT in South Africa have identified low-surface-brightness features, including extended radio halos that span entire clusters and bridge-like emissions linking cluster pairs. These findings provide the first confirmed radio signatures of the denser portions of the web.
The SKA’s large collecting area and improved sensitivity are expected to extend these studies to the more tenuous intergalactic medium within filaments, allowing researchers to trace the distribution of ordinary (baryonic) matter and its dynamical evolution across cosmic time.
