Radio Properties of Brightest Cluster Members

Abstract

We searched the literature for radio continuum images and flu x densities of the brightest cluster members (BCMs) in 1169 Abell clusters. The clusters were selected on the basis of their morphological type (Bautz-Morgan or Rood-Sastry) 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 morpho logies for 1423 BCMs in these clusters. We found 578 (41 %) of these BCMs with detected radio emission, of which 223 are detected at only a single frequency, usually at 1.4 GHz (NVSS or FIRST) or 843 MHz (SUMSS). Using the survey images and additional 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. Digitized Sky Survey 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 simila r bimodality as reported previously for a larger BCM sample, though the distribution is statisti cally indistinguishable from a uniform one. The shape of the distribution is independent of optical ellipticity, optical morphological type and largest linear radio size of the objects. In order to sele ct clusters with dominant central galaxies, the above-mentioned criteria appear to be too restrict ive. From the present study 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 r elations between these parameters and the radio-optical alignment, as well as to quantify the radi o morphology and search for relations with the peculiar velocity of the BCMs in their host cluster.