In the local Universe, high-power radio galaxies live in lower density environments than lowluminosity radio galaxies. If this trend continues to higher redshifts, powerful radio galaxies would serve as efficient probes of moderate redshift groups and poor clusters. Photometric studies of radio galaxies at 0.3 . z . 0.5 suggest that the radio luminosity-environment correlation disappears at mod...

Black holes with masses Mbh ∼ 10M⊙ dominate the accretion history of the Universe. These black hole masses are typical of those found in radio-selected galaxies today, suggesting that the giant elliptical hosts of low redshift radio galaxies were the hosts of powerful, mostly radio-quiet, quasars in the high redshift Universe. The reason that all radio galaxies are found in such hosts may be th...

Context. This paper presents the X-ray properties of a fluxand volume-limited complete sample of 16 Giga-Hertz Peaked Spectrum (GPS) galaxies. Aims. This study addresses three basic questions in our understanding of the nature and evolution of GPS sources: a) What is the physical origin of the X-ray emission in GPS galaxies? b) What physical system is associated with the X-ray obscuration? c) W...

We estimated black hole masses for 9 Seyfert 1 and 13 Seyfert 2 galaxies in the Palomar and CfA bright Seyfert samples using the tight correlation between black hole mass and bulge velocity dispersion. Combining other 13 Seyfert 1s and 2 Seyfert 2s in these samples but with black hole masses measured recently by reverberation mapping and stellar/gas dynamics, we studied the correlations of blac...

The host galaxies of powerful radio sources are ideal laboratories to study active galactic nuclei (AGN). The galaxies themselves are among the most massive systems in the universe, and are believed to harbor supermassive black holes (SMBH). If large galaxies are formed in a hierarchical way by multiple merger events, radio galaxies at low redshift represent the end-products of this process. Ho...

We have examined the stacked radio and X-ray emission from UV-selected galaxies spectroscopically confirmed to lie between redshifts 1.5 ∼< z ∼< 3.0 in the GOODS-North field to determine their average extinction and star formation rates (SFRs). The X-ray and radio data are obtained from the Chandra 2 Msec survey and the Very Large Array, respectively. There is a good agreement between the Xray,...

It is shown that, for Broad Line Radio Galaxies the strength of the nonthermal beamed radiation, when present, is always smaller than the accretion flow by a factor < 0.7 in the 2-10 keV band. The result has been obtained using the procedure adopted for disentangling the Flat Spectrum Radio Quasar 3C 273 (Grandi & Palumbo 2004) Although this implies a significantly smaller nonthermal flux in Ra...

Evidence for extended active lifetimes (> 10 yr) for radio galaxies implies that many large radio lobes were produced during the “quasar era”, 1.5 < z < 3, when the comoving density of radio sources was 2 – 3 dex higher than the present level. However, inverse Compton losses against the intense microwave background substantially reduce the ages and numbers of sources that are detected in fluxli...

We investigate the relationship between faint X-ray and 1.4 GHz radio source populations detected within 3 of the Hubble Deep Field North using the 1 Ms Chandra and 40 μJy VLA surveys. Within this region, we find that ≈42% of the 62 X-ray sources have radio counterparts and ≈71% of the 28 radio sources have X-ray counterparts; thus a 40 μJy VLA survey at 1.4 GHz appears to be well-matched to a ...

We explore the cosmic evolution of radio detected star forming (SF) galaxies and active galactic nuclei (AGN), drawn from the VLA-COSMOS survey, out to z = 1.3. We present the 20 cm radio luminosity function for these populations, and find that SF galaxies evolve much more rapidly than low-power radio AGN. Our results imply that weak radio AGN (L1.4GHz . 5×1025 WHz) occur in the most massive ga...