In this paper we present Very Large Array (VLA) 1.4 GHz (21 cm) observations of the region between the centres of A3558 and A3562, in the major cluster merger complex of the Shapley Concentration. Our final catalogue includes a total of 174 radio sources above the flux density limit of 0.25 mJy b −1. By cross-correlation with optical and spectroscopic catalogues we found 33 optical counterparts...

We have detected the H92α radio recombination line from two dwarf starburst galaxies, NGC 5253 and He 2-10, using the Very Large Array. Both the line data as well as the radio continuum data are used to model the properties of the ionized gas in the centers of these galaxies. We consider a multi-density model for radio recombination lines and show why previous models, which were based on the as...

We present deep 1.4 GHz Very Large Array (VLA) radio continuum observations of two ∼half square degree fields in the Coma cluster of galaxies. The two fields, “Coma 1” and “Coma 3,” correspond to the cluster core and southwest infall region and were selected on account of abundant pre-existing multiwavelength data. In their most sensitive regions the radio data reach 22 μJy rms per 4. 4 beam, s...

Radio flux densities of Shapley-Ames galaxies at λ2.8 cm from Niklas et al. (1995a, Paper I) and at λ20 cm from Condon (1987, C87) have been used to investigate the radio – far infrared (FIR) correlation at two different radio wavelengths. The correlation between monochromatic radio and the FIR luminosity was found to be non-linear (P2.8cm ∝ L1.09±0.04 FIR and P20cm ∝ L1.23±0.05 FIR ). Galaxies...

The Coma cluster is peculiar in the radio domain owing to the presence of cluster-wide diffuse sources: the radio halo Coma C, the relic source 1253+275, and the bridge between them. Diffuse radio sources in clusters are a rare and poorly understood phenomenon. We summarize here the properties of the diffuse radio sources in Coma and their relation to other cluster properties. 1 Radio emission ...

Radio continuum observations are a probe of star formation in galaxies, and are unaffected by dust extinction. Observations of the distant rich cluster Cl 0939+4713 have detected radio galaxies classified as post-starburst (“k+a”) on the basis of their optical spectra, and presumably this situation arises from heavily dust-obscured star formation (Smail et al. 1999). We present the results of a...

We present a Spitzer mid-infrared survey of 42 Fanaroff-Riley class II radio galaxies and quasars from the 3CRR catalog at redshift z < 1. All of the quasars and 45±12% of the narrow-line radio galaxies have a mid-IR luminosity of νLν(15μm) > 8 × 10 43 erg s, indicating strong thermal emission from hot dust in the active galactic nucleus. Our results demonstrate the power of Spitzer to unveil d...

A X-ray background synthesis model is used to calculate the contribution of Active Galactic Nuclei (AGNs) to the 1.4 GHz number counts between 100 nJy and 10 mJy. The number counts are broken down into contributions from radioquiet and radio-loud AGNs, obscured and unobscured AGNs, and for different ranges in redshift and 2–10 keV X-ray luminosity, LX . Compton-thick AGNs are included, but only...

We compare the arcsecond-scale circumnuclear radio continuum properties between five Seyfert and five starburst galaxies, concentrating on the search for any structures that could imply a spatial or causal connection between the nuclear activity and a circumnuclear starburst ring. No evidence is found in the radio emission for a link between the triggering or feeding of nuclear activity and the...

Recent Spitzer observations have revealed a substantial population of z ∼ 2 ultraluminous infrared galaxies (ULIRGs) with deep silicate absorption ( ). This paper reports a 20 cm radio study of such a sample to t 1 1 9.7 elucidate their physical nature. We discover that a substantial fraction (40%) of deep silicate absorption ULIRGs at z ∼ 2 are moderately radio-loud, with W Hz . This is in str...