A GMRT Narrowband vs. Wideband Analysis of the ACT-CLJ0034.4+0225 Field Selected from the ACTPol Cluster Sample

TL;DR

This paper compares narrowband and wideband radio observations of galaxy clusters, focusing on diffuse emissions like radio halos, using advanced interferometric techniques and the uGMRT, to improve detection and analysis methods.

Contribution

It develops and evaluates interferometric techniques for extracting faint diffuse radio emissions in galaxy clusters from wide-field broadband data.

Findings

Confirmed radio halo in ACT-CL J0034.4+0225

Wideband pipeline outperforms narrowband in this case

Severe artefacts require further image quality improvements

Abstract

Low frequency radio observations of galaxy clusters are a useful probe of the non-thermal intracluster medium (ICM), through observations of diffuse radio emission such as radio halos and relics. Current formation theories cannot fully account for some of the observed properties of this emission. In this study, we focus on the development of interferometric techniques for extracting extended, faint diffuse emissions in the presence of bright, compact sources in wide-field and broadband continuum imaging data. We aim to apply these techniques to the study of radio halos, relics and radio mini-halos using a uniformly selected and complete sample of galaxy clusters selected via the Sunyaev-Zel'dovich (SZ) effect by the Atacama Cosmology Telescope (ACT) project, and its polarimetric extension (ACTPol). We use the upgraded Giant Metrewave Radio Telescope (uGMRT) for targeted radio observations of a sample of 40 clusters. We present an overview of our sample, confirm the detection of a radio halo in ACT-CL J0034.4+0225, and compare the narrowband and wideband analysis results for this cluster. Due to the complexity of the ACT-CL J0034.4+0225 field, we use three pipelines to process the wideband data. We conclude that the experimental SPAM wideband pipeline produces the best results for this particular field. However, due to the severe artefacts in the field, further analysis is required to improve the image quality.