Extended stellar kinematics of elliptical galaxies in the Fornax cluster

We present extended stellar kinematics for a sample of 13 elliptical galaxies in the Fornax cluster. Major-axis velocity dispersion profiles (VDPs) and rotation curves (RCs) are given for 12 of the galaxies. A major feature of this data is the spatial extension: for 8 galaxies the data extends beyond 1 R_e, and for 5 it extends beyond 2 R_e. Compared to the previously available data, this corresponds to an increase in spatial coverage by a factor from 1 to 5. Five of the ellipticals in the sample turn out to be rotationally-supported systems, having positive rotation parameter log (V/sigma)*. One of these five, and another 3 galaxies from the remaining sample, display evidence for bar-like kinematics. The data indicate that the true number of `dynamically hot' stellar systems, is much lower than previously thought: of the Es in the present sample only 1/4 are confirmed as `pressure-supported' systems. The data reveal a host of individual peculiarities, like: wiggles, strong gradients, and asymmetries in the rotation curve and/or in the velocity dispersion profile, thus showing that the presence of kinematically distinct components and/or triaxiality is a common characteristic of this class of object.Comment: 27 pages, includes 15 eps figures. Accepted for publication in A&A Sup

Shapley Supercluster Survey: mapping the dark matter distribution

We present a 23deg$^2$ weak gravitational lensing survey of the Shapley supercluster core and its surroundings using $gri$ VST images as part of the Shapley Supercluster Survey (ShaSS). This study reveals the overall matter distribution over a region containing 11 clusters at $z{\sim}0.048$ that are all interconnected, as well as several ongoing cluster-cluster interactions. Galaxy shapes have been measured by using the Kaiser-Squires-Broadhurst method for the $g$- and $r$-band images and background galaxies were selected via the $gri$ colour-colour diagram. This technique has allowed us to detect all of the clusters, either in the $g$-band or $r$-band images, although at different $\sigma$ levels, indicating that the underlying dark matter distribution is tightly correlated with the number density of the member galaxies. The deeper $r$-band images have traced the five interacting clusters in the supercluster core as a single coherent structure, confirmed the presence of a filament extending North from the core, and have revealed a background cluster at $z{\sim}0.17$. We have measured the masses of the four richest clusters (A3556, A3558, A3560 and A3562) in the two-dimensional shear pattern, assuming a spherical Navarro-Frenk-White (NFW) profile and obtaining a total mass of $\mathcal{M}_{\rm ShaSS,WL}{=}1.56^{+0.81}_{-0.55}{\times}10^{15\,}{\rm M}_{\odot}$, which is consistent with dynamical and X-ray studies. Our analysis provides further evidence of the ongoing dynamical evolution in the ShaSS region.Comment: 16 pages, 11 figures, 4 tables. Accepted for publication in MNRA

An Interacting Galaxy Pair at the Origin of a Light Echo

In a low-density region of the Shapley supercluster we identified an interacting galaxy pair at redshift z = 0.04865 in which the Seyfert 2 nucleus of the main galaxy (ShaSS 073) is exciting an extended emission line region (EELR, ∼170 kpc^2) in the disk of the less massive companion (ShaSS 622). New integral-field spectroscopy and the multiband data set, spanning from far-ultraviolet to far-infrared and radio wavelengths, allowed us to obtain a detailed description of the ShaSS 622-073 system. The gas kinematics shows hints of interaction, although the overall velocity field shows a quite regular rotation in both galaxies, thus suggesting that we are observing their first encounter as confirmed by the estimated distance of 21 kpc between the two galaxy centers. The detected ∼ 2-3 kpc active galactic nucleus (AGN) outflow and the geometry of the EELR in ShaSS 622 support the presence of a hollow bicone structure. The status and sources of the ionization across the whole system have been analyzed through photoionization models and a Bayesian approach that prove a clear connection between the AGN and the EELR. The luminosity of the AGN (2.4×10^44 erg/s) is a factor of 20 lower than the power needed to excite the gas in the EELR (4.6 ×10^45 erg/s), indicating a dramatic fading of the AGN in the past 3×10^4 yr. ShaSS 073-622 provides all the ingredients listed in the recipe of a light echo where a highly-ionized region maintains memory of a preceding more energetic phase of a now-faded AGN. This is the first case of a light echo observed between two galaxies

A complete data base of kinematical data for early-type galaxies

As a result of an exhaustive bibliographical search covering the period 1975-1988, a complete catalogue of kinematical data for early-type galaxies (ellipticals and lenticulars) has been compiled. The catalogue contains all data both in tabular and in plotted form--appeared in specialized literature before December 1988 and includes central velocity dispersions, rotation curves, and velocity dispersion profiles for 846, 174 and 108 objects, respectively. The catalogue is also available on magnetic tape---made available to the astronomical community through the Strasbourg Data Center--and will be updated yearly

Shapley supercluster survey: mapping the dark matter distribution

We present a 23 deg2 weak gravitational lensing survey of the Shapley supercluster core and its surroundings using gri VST images as part of the Shapley Supercluster Survey (ShaSS). This study reveals the overall matter distribution over a region containing 11 clusters at z ∼ 0.048 that are all interconnected, as well as several ongoing cluster-cluster interactions. Galaxy shapes have been measured by using the Kaiser-Squires-Broadhurst method for the g- and r-band images and background galaxies were selected via the gri colour-colour diagram. This technique has allowed us to detect all of the clusters, either in the g- or r-band images, although at different σ levels, indicating that the underlying dark matter distribution is tightly correlated with the number density of the member galaxies. The deeper r-band images have traced the five interacting clusters in the supercluster core as a single coherent structure, confirmed the presence of a filament extending North from the core, and have revealed a background cluster at z ∼ 0.17. We have measured the masses of the four richest clusters (A3556, A3558, A3560, and A3562) in the two-dimensional shear pattern, assuming a spherical Navarro-Frenk-White profile and obtaining a total mass of $\mathcal {M}_{\rm ShaSS,WL}{=}1.56^{+0.81}_{-0.55}{\times }10^{15\, }{\rm M}_{\odot }$ , which is consistent with dynamical and X-ray studies. Our analysis provides further evidence of the ongoing dynamical evolution in the ShaSS region

Shapley Supercluster Survey

Our multi-wavelength survey of the Shapley supercluster (z ∼ 0.05) covers a contiguous area of 260 h 70-2Mpc2including the supercluster core. The project's main aim is to quantify the influence of cluster-scale mass assembly on galaxy evolution in one of the most massive structures in the local Universe. The Shapley supercluster survey (ShaSS) includes nine Abell clusters (A 3552, A 3554, A 3556, A 3558, A 3559, A 3560, A 3562, AS 0724, AS 0726) and two poor clusters (SC 1327-312, SC 1329-313) showing evidence of cluster-cluster interactions. Optical (ugri) and near-infrared (K) imaging acquired with VST and VISTA allow us to study the galaxy population down to m^{star} + 6 at the supercluster redshift. A dedicated spectroscopic survey with AAOmega on the Anglo-Australian Telescope provides a magnitude-limited sample of supercluster members with 80 % completeness at ∼ m^{star} + 3

Cosmic dance in the Shapley Concentration Core. I. A study of the radio emission of the BCGs and tailed radio galaxies

Context. The Shapley Concentration (⟨z⟩ ≈ 0.048) covers several degrees in the southern hemisphere, and includes galaxy clusters in advanced evolutionary stages, groups of clusters in the very early stages of merger, fairly massive clusters with ongoing accretion activity, and smaller groups located in filaments in the regions between the main clusters. Aims: With the goal to investigate the role of cluster mergers and accretion on the radio galaxy population, we performed a multi-wavelength study of the brightest cluster galaxies (BCGs) and of the galaxies showing extended radio emission in the cluster complexes of Abell 3528 and Abell 3558. In total, our study is based on a sample of 12 galaxies. Methods: We observed the clusters with the Giant Metrewave Radio Telescope (GMRT) at 235, 325, and 610 MHz, and with the Very Large Array (VLA) at 8.46 GHz. We complemented our study with the TIFR GMRT Sky Survey (TGSS) at 150 MHz, the Sydney University Molonglo Sky Survey (SUMSS) at 843 MHz, and the Australia Telescope Compact array (ATCA) at 1380, 1400, 2380, and 4790 MHz data. Finally, optical imaging with the VLT Survey Telescope (VST) is also available for the host galaxies as well as the mid-infrared coverage with the Wide-Field Infrared Survey Explorer (WISE). Results: We found significant differences in the properties of the radio emission of the BCGs in the two cluster complexes. The BCGs in the A 3528 complex and in A 3556, which are relaxed cool-core objects, are powerful active radio galaxies. They also present hints of restarted activity. On the contrary, the BCGs in A 3558 and A 3562, which are well-known merging systems, are very faint, or quiet, in the radio band. The optical and infrared properties of the galaxies, on the other hand, are fairly similar in the two complexes, showing all passive red galaxies. Conclusions: Our study shows remarkable differences in the radio properties of the BGCs, which we relate to the different dynamical state of the host cluster. On the contrary, the lack of changes between such different environments in the optical band suggests that the dynamical state of galaxy clusters does not affect the optical counterparts of the radio galaxies, at least over the lifetime of the radio emission

Shapley Supercluster Survey: construction of the photometric catalogues and i-band data release

The Shapley Supercluster Survey is a multi-wavelength survey covering an area of ̃23 deg2(̃260 Mpc2at z = 0.048) around the supercluster core, including nine Abell and two poor clusters, having redshifts in the range 0.045-0.050. The survey aims to investigate the role of the cluster-scale mass assembly on the evolution of galaxies, mapping the effects of the environment from the cores of the clusters to their outskirts and along the filaments. The optical (ugri) imaging acquired with OmegaCAM on the VLT Survey Telescope is essential to achieve the project goals providing accurate multi-band photometry for the galaxy population down to m* + 6. We describe the methodology adopted to construct the optical catalogues and to separate extended and point-like sources. The catalogues reach average 5σ limiting magnitudes within a 3 arcsec diameter aperture of ugri = [24.4,24.6,24.1,23.3] and are 93 per cent complete down to ugri = [23.8,23.8,23.5,22.0] mag, corresponding to ̃m*r+ 8.5. The data are highly uniform in terms of observing conditions and all acquired with seeing less than 1.1 arcsec full width at half-maximum. The median seeing in r band is 0.6 arcsec, corresponding to 0.56 kpc h^{-1}_{70} at z = 0.048. While the observations in the u, g and r bands are still ongoing, the i-band observations have been completed, and we present the i-band catalogue over the whole survey area. The latter is released and it will be regularly updated, through the use of the Virtual Observatory tools. This includes 734 319 sources down to i = 22.0 mag and it is the first optical homogeneous catalogue at such a depth, covering the central region of the Shapley supercluster

Shapley Supercluster Survey: Galaxy evolution from filaments to cluster cores

We present an overview of a multiwavelength survey of the Shapley Supercluster (SSC; z ̃ 0.05) covering a contiguous area of 260 h^{-2}_{70} Mpc2including the supercluster core. The project main aim is to quantify the influence of cluster-scale mass assembly on galaxy evolution in one of the most massive structures in the local Universe. The Shapley Supercluster Survey (ShaSS) includes nine Abell clusters (A3552, A3554, A3556, A3558, A3559, A3560, A3562, AS0724, AS0726) and two poor clusters (SC1327-312, SC1329-313) showing evidence of cluster-cluster interactions. Optical (ugri) and near-infrared (K) imaging acquired with VLT Survey Telescope and Visible and Infrared Survey Telescope for Astronomy allow us to study the galaxy population down to m⋆+ 6 at the supercluster redshift. A dedicated spectroscopic survey with AAOmega on the Anglo-Australian Telescope provides a magnitude-limited sample of supercluster members with 80 per cent completeness at ̃m⋆+ 3. We derive the galaxy density across the whole area, demonstrating that all structures within this area are embedded in a single network of clusters, groups and filaments. The stellar mass density in the core of the SSC is always higher than 9 × 109M☉Mpc-3, which is ̃40× the cosmic stellar mass density for galaxies in the local Universe. We find a new filamentary structure (̃7 Mpc long in projection) connecting the SSC core to the cluster A3559, as well as previously unidentified density peaks. We perform a weak-lensing analysis of the central 1 deg2field of the survey obtaining for the central cluster A3558 a mass of M_{500}=7.63_{-3.40}^{+3.88}× 10^{14} M_{☉}, in agreement with X-ray based estimates