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Aims.We present photoionization calculations for the spatially-extended absorbers observed in front of the extended emission-line spectrum of two high-redshift radio galaxies, 0943–242 (ze) and 0200+015 (ze), with the aim of reproducing the absorber column ratio, $N_{\rm CIV}/N_{\rm HI}$.

We have measured the angular correlation function, $w(\theta)$, of radio sources in the 1.4 GHz NVSS and FIRST radio surveys. Below ~$6\arcmin$the signal is dominated by the size distribution of classical double radio galaxies, an effect underestimated in some previous studies. We model the physical size distribution of FRII radio galaxies to account for this excess signal in $w(\theta)$. The amplitude of the true cosmological clustering of radio sources is roughly constant at $A\simeq1\times10^{-3}$for flux limits of 3–40 mJy, but has increased to $A\simeq7\times10^{-3}$at 200 mJy. This can be explained if powerful (FRII) radio galaxies probe significantly more massive structures compared to radio galaxies of average power at $z\sim1$. This is consistent with powerful high-redshift radio galaxies generally having massive (forming) elliptical hosts in rich (proto-)cluster environments. For FRIIs we derive a spatial (comoving) correlation length of $r_0=14\pm3$h-1Mpc. This is remarkably close to that measured for extremely red objects (EROs) associated with a population of old elliptical galaxies at $z\sim1$by [CITE]. Based on their similar clustering properties, we propose that EROs and powerful radio galaxies may be the same systems seen at different evolutionary stages. Their r0is ~$2\times$higher than that of QSOs at a similar redshift, and comparable to that of bright ellipticals locally. This suggests that r0(comoving) of these galaxies has changed little from $z\sim1$to $z=0$, in agreement with current ΛCDM hierarchical merging models for the clustering evolution of massive early-type galaxies. Alternatively, the clustering of radio galaxies can be explained by the galaxy conservation model. This then implies that radio galaxies of average power are the progenitors of the local field population of early-types, while the most powerful radio galaxies will evolve into a present-day population with r0comparable to that of local rich clusters.

Results are summarized from a program of VLT-UVES echelle spectroscopy on the HI Lyα absorption in z > 2 radio galaxies. The nature and incidence of this absorption are reviewed, along with scenarios for its origin. Comparison is made with integral field spectroscopy of the two radio-quiet 100 kpc-scale Lyα haloes in the z = 3.09 SSA22 protocluster–the Steidel Lyα blobs. The emphasis is on using such absorption to study the injection of energy and metals from radio jets and starburst superwinds, processes considered vital to the formation of the most massive galaxies. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

We report long, pointed ROSATHRI observations of the hyperluminous galaxies IRAS F00235+1024, F12514+1027, F14481+4454 and F14537+1950. Two of them are optically classified as Seyfert‐like. No X‐ray sources are detected at the positions of any of the objects, with a mean upper limit LX/LBol≃ 2.3 × 10−4. This indicates that any active nuclei are either atypically weak at X‐ray wavelengths or obscured by column densities NH> 1023cm−2. They differ markedly from ‘ordinary’ Seyfert 2 galaxies, bearing a closer resemblance in the soft X‐ray band to composite Seyfert 2 galaxies or to some types of starburst.

The dust destruction timescales in the cores of clusters of galaxies are relatively short given their high central gas densities. However, substantial mid-infrared and sub-mm emission has been detected in many brightest cluster galaxies. In this letter we present HerschelPACS and SPIRE photometry of the brightest cluster galaxy in three strong cooling flow clusters, A1068, A2597 and Zw3146. This photometry indicates that a substantial mass of cold dust is present (> 3×107$M_\odot$) at temperatures significantly lower (20–28 K) than previously thought based on limited MIR and/or sub-mm results. The mass and temperature of the dust appear to match those of the cold gas traced by CO with a gas-to-dust ratio of 80–120.

The question of how much gas cools in the cores of clusters of galaxies has been the focus of many, multiwavelength studies in the past 30 years. In this letter we present the first detections of the strongest atomic cooling lines, [Cii], [Oi] and [Nii] in two strong cooling flow clusters, A1068 and A2597, using Herschel-PACS. These spectra indicate that the substantial mass of cold molecular gas (> 109$M_\odot$) known to be present in these systems is being irradiated by intense UV radiation, most probably from young stars. The line widths of these FIR lines indicate that they share dynamics similar but not identical to other ionised and molecular gas traced by optical, near-infrared and CO lines. The relative brightness of the FIR lines compared to CO and FIR luminosity is consistent with other star-forming galaxies indicating that the properties of the molecular gas clouds in cluster cores and the stars they form are not unusual. These results provide additional evidence for a reservoir of cold gas that is fed by the cooling of gas in the cores of the most compact clusters and provide important diagnostics of the temperature and density of the dense clouds this gas resides in.

The question of how much gas cools in the cores of clusters of galaxies has been the focus of many, multiwavelength studies in the past 30 years. In this letter we present the first detections of the strongest atomic cooling lines, [Cii], [Oi] and [Nii] in two strong cooling flow clusters, A1068 and A2597, using Herschel-PACS. These spectra indicate that the substantial mass of cold molecular gas (> 109$M_\odot$) known to be present in these systems is being irradiated by intense UV radiation, most probably from young stars. The line widths of these FIR lines indicate that they share dynamics similar but not identical to other ionised and molecular gas traced by optical, near-infrared and CO lines. The relative brightness of the FIR lines compared to CO and FIR luminosity is consistent with other star-forming galaxies indicating that the properties of the molecular gas clouds in cluster cores and the stars they form are not unusual. These results provide additional evidence for a reservoir of cold gas that is fed by the cooling of gas in the cores of the most compact clusters and provide important diagnostics of the temperature and density of the dense clouds this gas resides in.

The dust destruction timescales in the cores of clusters of galaxies are relatively short given their high central gas densities. However, substantial mid-infrared and sub-mm emission has been detected in many brightest cluster galaxies. In this letter we present HerschelPACS and SPIRE photometry of the brightest cluster galaxy in three strong cooling flow clusters, A1068, A2597 and Zw3146. This photometry indicates that a substantial mass of cold dust is present (> 3×107$M_\odot$) at temperatures significantly lower (20–28 K) than previously thought based on limited MIR and/or sub-mm results. The mass and temperature of the dust appear to match those of the cold gas traced by CO with a gas-to-dust ratio of 80–120.