The role of the environment of an elliptical galaxy on its hot interstellar gas is discussed. In general, the X-ray halos of early-type galaxies tend to be smaller and fainter in denser environments, with the exception of group-central galaxies. X-ray observations show many examples of nearby galaxies which are undergoing gas stripping. On the other hand, most bright galaxies in clusters do man...

We present a statistical study of several fundamental properties of radio sources in nearby clusters (z ≤ 0.2), including the radial distribution within clusters, the radio luminosity function (RLF), and the fraction of galaxies that is radio-active (radio active fraction, RAF). The analysis is carried out for a sample of 573 clusters detected in the X–ray and also observed at 1.4 GHz in the NR...

In the local Universe, the majority of radio-loud AGN are found in massive elliptical galaxies with old stellar populations and weak or undetected emission lines. At high redshifts, however, almost all known radio AGN have strong emission lines. This paper focuses on a subset of radio AGN with emission lines (EL-RAGN) selected from the Sloan Digital Sky Survey. We explore the hypothesis that th...

Most radiation from galaxies containing active galactic nuclei (AGNs) is emitted not by the stars composing the galaxy, but from an active source at the galactic center, most likely a supermassive black hole. Of particular interest are radio galaxies, active galaxies that emit much of their radiation at radio wavelengths. Within each radio galaxy, an AGN powers a pair of collimated jets of rela...

The masses of the central supermassive black holes and the Eddington ratios for a sample of 65 young radio galaxies [27 gigahertz-peaked spectrum (GPS) and 38 compact steepspectrum (CSS) sources] are estimated by various methods. We find that the average BH mass of these young radio galaxies is ≃ 8.3, which is less than that of radio loud QSOs and low redshift radio galaxies (≃ ...

Recent measurements of the galaxy clustering environments around intermediate-redshift radio sources have suggested a systematic environmental difference between radio galaxies and radio-loud quasars, in contradiction to the predictions of simple unified models for the two classes of object. I show that the apparent difference arises mainly as a result of the properties of low-excitation radio ...

The Eridanus galaxies follow the well-known radio-FIR correlation. Majority (70%) of these galaxies have their star formation rates below that of the Milky Way. The galaxies having a significant excess of radio emission are identified as low lumi-nosity AGNs based on their radio morphologies obtained from the GMRT observations. There are no powerful AGNs (L 20cm > 10 23 W Hz −1) in the group. T...

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 investigate the correlations between optical and radio isophotal position angles for 14302 SDSS galaxies with r magnitudes brighter than 18 and which have been associated with extended FIRST radio sources. We identify two separate populations of galaxies using the colour, concentration and their principal components. Surprisingly strong statistical alignments are found: late-type galaxies ar...

We report the detection of CO (1 → 0) and CO (2 → 1) emission from the central regions (. 5–10 kpc) of the two powerful radio galaxies 3C 31 and 3C 264. Their individual CO emission exhibits a double-horned line profile that is characteristic of an inclined rotating disk with a central depression at the rising part of its rotation curve. The inferred disk or ring distributions of the molecular ...