Radio Properties of Brightest Cluster Members

TL;DR

This study compiles and analyzes radio data for brightest cluster members in 1169 clusters, examining their radio properties, orientations, and potential correlations with optical features to better understand their nature and evolution.

Contribution

It provides a comprehensive catalog of radio fluxes and morphologies for BCMs, including orientation analysis and statistical insights into their alignment with optical axes.

Findings

41% of BCMs have detected radio emission

Distribution of radio-optical axis differences shows bimodality

No significant correlation between radio-optical alignment and optical properties

Abstract

We searched the literature for radio images and fluxes of brightest cluster members (BCMs) in 1169 Abell clusters, selected on the basis of their BM or RS type or on textual notes in the Abell catalog indicating the presence of dominant galaxies. We inspected the images of existing radio surveys (NVSS, SUMSS, FIRST, WENSS, etc.) and used the CATS and VizieR catalog browsers, as well as additional literature, to collect radio fluxes and radio morphologies for 1423 BCMs. We found 578 (41%) of these BCMs with detected radio emission, of which 223 are detected at only a single frequency. Using the survey images and published high-resolution images, we estimated the best available position angle for the innermost radio structure and for the largest angular size of each source. DSS images were used to obtain the orientation of the optical major axis of the outer envelope of the BCMs, and the acute difference angle between major optical and radio axes was derived for 102 objects. Its distribution shows a similar bimodality as reported previously for a larger BCM sample, although KS tests do not distinguish them from uniform ones. The shape of the distribution is independent of optical ellipticity, optical morphological type and largest linear radio size of the objects. In order to find further clusters with dominant central galaxies, the above-mentioned criteria need to be relaxed. There is at most marginal evidence for a relation between powerful high-redshift radio galaxies and dominant galaxies of low-z clusters when comparing their radio-optical alignment angle. We plan to derive radio spectra, radio luminosities and search for possible relations between these parameters and the radio-optical alignment, as well as to relate their radio morphologies with the available BCM peculiar velocities.