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We examine the radio properties of the brightest cluster galaxies (BCGs) in a large sample of X-ray selected galaxy clusters comprising the Brightest Cluster Sample (BCS), the extended BCS and ROSAT-ESO Flux Limited X-ray cluster catalogues. We have multifrequency radio observations of the BCG using a variety of data from the Australia Telescope Compact Array, Jansky Very Large Array and Very Long Baseline Array telescopes. The radio spectral energy distributions of these objects are decomposed into a component attributed to on-going accretion by the active galactic nuclei (AGN) that we refer to as 'the core', and a more diffuse, ageing component we refer to as the 'non-core'. These BCGs are matched to previous studies to determine whether they exhibit emission lines (principally Hα), indicative of the presence of a strong cooling cluster core. We consider how the radio properties of the BCGs vary with cluster environmental factors. Line emitting BCGs are shown to generally host more powerful radio sources, exhibiting the presence of a strong, distinguishable core component in about 60 per cent of cases. This core component more strongly correlates with the BCG's [O III] 5007 Å line emission. For BCGs in line emitting clusters, the X-ray cavity power correlates with both the extended and core radio emission, suggestive of steady fuelling of the AGN over bubble-rise time-scales in these clusters. [ABSTRACT FROM AUTHOR]

We present Spitzer high-resolution spectra of off-nuclear regions in the central cluster galaxies NGC 1275 and NGC 4696 in the Perseus and Centaurus clusters, respectively. Both objects are surrounded by extensive optical emission-line filamentary nebulae, bright outer parts of which are the targets of our observations. The 10–37 μm spectra show strong pure-rotational lines from molecular hydrogen revealing a molecular component to the filaments which has an excitation temperature of ∼300−400 K. The flux in the 0−0 S(1) molecular hydrogen line correlates well with the strength of the optical lines, having about 3 per cent of the Hα+[N ii] emission. The 11.3-μm polycyclic aromatic hydrocarbon feature is seen in some spectra. Emission is also seen from both low- and high-ionization fine-structure lines. Molecular hydrogen cooler than ∼400 K dominates the mass of the outer filaments; the nebulae are predominantly molecular. [ABSTRACT FROM AUTHOR]

We exploit the gravitational potential of a massive, rich cluster at to study the internal properties of a gravitationally lensed galaxy at . Using high-resolution Hubble Space Telescope imaging together with optical (VIMOS) and near-infrared (SINFONI) integral field spectroscopy, we have studied the rest-frame ultraviolet and optical properties of the lensed galaxy seen through the cluster RCS0224−002. Using a detailed gravitational lens model of the cluster, we reconstruct the source-frame morphology on 200 pc scales and find an Lyman-break galaxy with an intrinsic size of only , a velocity gradient of and an implied dynamical mass of within 2 kpc. We infer an integrated star formation rate of just from the intrinsic [O ii]λ3727 emission-line flux. The Lyα emission appears redshifted by with respect to the [O ii] emission. The Lyα is also significantly more extended than the nebular emission, extending over 11.9 × 2.4 kpc. Over this area, the Lyα centroid varies by less than . We model the asymmetric Lyα emission with an underlying Gaussian profile with an absorber in the blue wing and find that the underlying Lyα emission-line centroid is in excellent agreement with the [O ii] emission-line redshift. By examining the spatially resolved structure of the [O ii] and Lyα emission lines, we investigate the nature of this system. The model for local starburst galaxies suggested by Mas-Hesse et al. provides a good description of our data, and suggests that the galaxy is surrounded by a galactic-scale bipolar outflow which has recently bursted out of the system. The outflow, which appears to be currently located ≳30 kpc from the galaxy, is escaping at a speed of upto . Although the mass of the outflow is uncertain, the geometry and velocity of the outflow suggests that the ejected material is travelling far faster than escape velocity and will travel more than 1 Mpc (comoving) before eventually stalling. [ABSTRACT FROM AUTHOR]