We present detailed, high spatial and spectral resolution, long-slit observations of four central cluster galaxies (Abell 0085, 0133, 0644 and Ophiuchus) recently obtained on the Southern African Large Telescope (SALT). Our sample consists of central
cluster galaxies (CCGs) with previously-observed Halpha-filaments, and have existing data from the X-ray to radio wavelength regimes available. Here, we present the detailed optical data over a broad wavelength range to probe the spatially-resolved kinematics and stellar populations of the stars. We use the Pegase.HR model with the ELODIE v3.1 stellar library to determine the star formation histories of the galaxies using full spectrum fitting. We perform single stellar population (SSP) as well as composite stellar population (CSP) fits to account for more complex star formation histories. Monte-Carlo simulations and chi 2-maps are used to check the reliability of the solutions. This, combined with the other multiwavelength data, will form a complete view of the different phases (hot and cold gas and stars) and how they interact in the processes of star formation and feedback detected in central galaxies in cooling flow clusters, as well as the influence of the host cluster. We find small, young stellar components in at least three of the four galaxies, even though two of the three host clusters have zero spectrally-derived mass deposition rates from X-ray observations.
We present detailed integral field unit (IFU) observations of the central few kiloparsecs of the ionised nebulae surrounding four active central cluster galaxies (CCGs) in cooling flow clusters (Abell 0496, 0780, 1644 and 2052). Our sample consists o
f CCGs with H{alpha} filaments, and have existing data from the X-ray regime available. Here, we present the detailed optical emission-line (and simultaneous absorption line) data over a broad wavelength range to probe the dominant ionisation processes, excitation sources, morphology and kinematics of the hot gas (as well as the morphology and kinematics of the stars). This, combined with the other multiwavelength data, will form a complete view of the different phases (hot and cold gas and stars) and how they interact in the processes of star formation and feedback detected in central galaxies in cooling flow clusters, as well as the influence of the host cluster. We derive the optical dust extinction maps of the four nebulae. We also derive a range of different kinematic properties, given the small sample size. For Abell 0496 and 0780, we find that the stars and gas are kinematically decoupled, and in the case of Abell 1644 we find that these components are aligned. For Abell 2052, we find that the gaseous components show rotation even though no rotation is apparent in the stellar components. To the degree that our spatial resolution reveals, it appears that all the optical forbidden and hydrogen recombination lines originate in the same gas for all the galaxies. Based on optical diagnostic ratios ([OIII]{lambda}5007/H{beta} against [NII]{lambda}6584/H{alpha}, [SII]{lambda}{lambda}6717,6731/H{alpha}, and [OI]{lambda}6300/H{alpha}), all galaxies show extended LINER emission, but that at least one has significant Seyfert emission areas, and at least one other has significant HII like emission line ratios for many pixels. ABRIDGED.
This paper is part of a series devoted to the study of the stellar populations in brightest cluster galaxies (BCGs), aimed at setting constraints on the formation and evolution of these objects. We have obtained high signal-to-noise ratio, long-slit
spectra of 49 BCGs in the nearby Universe. Here, we derive Single Stellar Population (SSP)-equivalent ages, metallicities and alpha-abundance ratios in the centres of the galaxies using the Lick/IDS system of absorption line indices. We systematically compare the indices and derived parameters for the BCGs with those of large samples of ordinary elliptical galaxies in the same mass range. We find no significant differences between the index-velocity dispersion relations of the BCG data and those of normal ellipticals, but we do find subtle differences between the derived SSP-parameters. The BCGs show, on average, higher metallicity ([Z/H]) and alpha-abundance ([E/Fe]) values. We analyse possible correlations between the derived parameters and the internal properties of the galaxies (velocity dispersion, rotation, luminosity) and those of the host clusters (density, mass, distance from BCG to X-ray peak, presence of cooling flows), with the aim of dissentangling if the BCG properties are more influenced by their internal or host cluster properties. The SSP-parameters show very little dependence on the mass or luminosity of the galaxies, or the mass or density of the host clusters. Of this sample, 26 per cent show luminosity-weighted ages younger than 6 Gyr, probably a consequence of recent - if small - episodes of star formation. In agreement with previous studies, the BCGs with intermediate ages tend to be found in cooling-flow clusters with large X-ray excess.
