XMM-Newton temperature maps for five intermediate redshift clusters of galaxies

We have analyzed XMM-Newton archive data for five clusters of galaxies (redshifts 0.223 to 0.313) covering a wide range of dynamical states, from relaxed objects to clusters undergoing several mergers. We present here temperature maps of the X-ray gas together with a preliminary interpretation of the formation history of these clusters.Comment: 4 pages, 2 figs. Accepted for publication in the Proceedings of the 36th COSPAR Scientific Assembl

Near infrared observations of quasars with extended ionized envelopes

We have observed a sample of 15 and 8 quasars with redshifts between 0.11 and 0.87 (mean value 0.38) in the J and K' bands respectively. Eleven of the quasars were previously known to be associated with extended emission line regions. After deconvolution of the image, substraction of the PSF when possible, and identification of companions with the help of HST archive images when available, extensions are seen for at least eleven quasars. However, average profiles are different from that of the PSF in only four objects, for which a good fit is obtained with an $r^{1/4}$ law, suggesting that the underlying galaxies are ellipticals. Redshifts were available in the literature for surrounding objects in five quasar fields. For these objects, one to five companion galaxies were found. One quasar even belongs to a richness class 1 cluster. Most other quasars in our sample have nearby galaxies in projection which may also be companions. Environmental effects are therefore probably important to account for the properties of these objects.Comment: Accepted for publication in A&A

Integral field spectroscopy of the radio galaxy 3C 171

We have performed integral field spectroscopy of the radio galaxy 3C 171 (redshift z=0.238) with the TIGER instrument at the Canada France Hawaii telescope in the Hbeta-[OIII]4959-5007 wavelength region. We present the reconstructed Hbeta and [OIII] images and compare them to the HST and radio maps. We discuss the variations of the [OIII]/Hbeta line ratio throughout the nebulosity. We also analyze the velocity field in detail, in particular the presence of several components. We find that the kinematics derived with emission lines in the central region (inside 1 arcsec) are compatible with a disk-like rotation of low amplitude (50 km/s). The continuum surface brightness profile follows an r^{1/4} law, suggesting that the underlying galaxy is an elliptical with an effective radius of 15 kpc. We have fit two components in the region centered 2.7 arcsec to the West and of extension 3 arcsec^2. We find that the blueshifted component is an extension of the central part, whereas the second one is redshifted by 600 km/s. In both components, line ratios and FWHM are compatible with the presence of shocks induced by jet-cloud interactions.Comment: 8 pages, 15 figures. Accepted for publication in A&A Main Journal (July, 3rd

The rich cluster of galaxies ABCG~85. IV. Emission line galaxies, luminosity function and dynamical properties

This paper is the fourth of a series dealing with the cluster of galaxies ABCG 85. Using our two extensive photometric and spectroscopic catalogues (with 4232 and 551 galaxies respectively), we discuss here three topics derived from optical data. First, we present the properties of emission line versus non-emission line galaxies, showing that their spatial distributions somewhat differ; emission line galaxies tend to be more concentrated in the south region where groups appear to be falling onto the main cluster, in agreement with the hypothesis (presented in our previous paper) that this infall may create a shock which can heat the X-ray emitting gas and also enhance star formation in galaxies. Then, we analyze the luminosity function in the R band, which shows the presence of a dip similar to that observed in other clusters at comparable absolute magnitudes; this result is interpreted as due to comparable distributions of spirals, ellipticals and dwarfs in these various clusters. Finally, we present the dynamical analysis of the cluster using parametric and non-parametric methods and compare the dynamical mass profiles obtained from the X-ray and optical data.Comment: accepted for publication in A&

A catalogue of velocities in the direction of the cluster of galaxies Abell 496

We present a catalogue of velocities for 466 galaxies in the direction of the cluster Abell 496, in a region covering about 160' x 160' (9.2 x 9.2 Mpc for an average redshift for Abell 496 of 0.0331, assuming H$_0$=50 km s$^{-1}$ Mpc$^{-1}$). This catalogue includes previously published redshifts by Proust et al. (1987), Quintana and Ramirez (1990) and Malumuth et al. (1992), redshifts from the CfA redshift survey, together with our new measurements. A total of 274 galaxies have velocities in the 7800-11800 km/s interval, and will be considered as members of the cluster. Abell 496 therefore becomes one of the few clusters with a high number of measured redshifts; its physical properties are investigated in a companion paper.Comment: Accepted for publication in Astronomy & Astrophysics, Supplement Serie

An optical view of the filament region of Abell 85

We compare the distribution of optically and Halpha (Ha) selected galaxies in the Southern half of the nearby Abell 85 (A85) cluster with the recently discovered X-ray filament (XRF). We search for galaxies where star formation (SF) may have been triggered by interactions with intracluster gas or tidal pressure due to the cluster potential when entering the cluster. Our analysis is based on images obtained with CFHT MegaPrime/MegaCam (1x1 deg2 field) in four bands (ugri) and ESO 2.2mWFI (38'x36' field) in a narrow band filter corresponding to the redshifted Halpha (Ha) line and in a broad R-band filter. The LFs are estimated by statistically subtracting a reference field. Background contamination is minimized by cutting out galaxies redder than the observed red sequence in the g-i vs. i colour-magnitude diagram. The galaxy distribution shows a significantly flattened cluster, whose principal axis is slightly offset from the XRF. The analysis of the broad band LFs shows that the filament region is well populated. The filament is also independently detected as a gravitationally bound structure by the Serna & Gerbal hierarchical method. 101 galaxies are detected in Ha, among which 23 have spectroscopic redshifts in the cluster, 2 have spectroscopic redshifts higher than the cluster and 58 have photometric redshifts that tend to indicate that they are background objects.The 23 galaxies with spectroscopic redshifts in the cluster are mostly concentrated in the South part of the cluster and along the filament. We find a number of galaxies showing evidence for SF in the XRF, and all our results are consistent with the previous hypothesis that the XRF in A85 is a gravitationally bound structure made of groups falling on to the main cluster.Comment: Accepted in A&A. 39 pages, 107 figures. Full resolution images available at ftp://ftp.iap.fr/pub/from_users/gam/A85

A catalogue of velocities in the cluster of galaxies Abell 85

We present a catalogue of velocities for 551 galaxies (and give the coordinates of 39 stars misclassified as galaxies in our photometric plate catalogue) in a region covering about 100'$\times$100' (0.94$\times$0.94 Mpc for an average redshift of 0.0555, assuming H$_\circ$=50 km s$^{-1}$ Mpc$^{-1}$) in the direction of the rich cluster Abell 85. This catalogue includes previously published redshifts by Beers et al. (1991) and Malumuth et al. (1992), together with our 367 new measurements. A total of 305 galaxies have velocities in the interval 13350-20000 km s$^{-1}$, and will be considered as members of the cluster. Abell 85 therefore becomes one of the clusters with the highest number of measured redshifts; its optical properties are being investigated in a companion paper.Comment: Accepted for publication in A&AS, Table 4 available in electronic form onl

A multi-wavelength analysis of the cluster of galaxies ABCG 194

(Abridged) We present a morphological and structural analysis of the Richness zero cluster ABCG 194, known as a ``linear cluster'', based on a catalogue of 97 galaxies with B magnitudes and redshifts, a ROSAT PSPC image and radio data. The overall large scale structure is rather smooth and comparable at optical and X-ray wavelengths. The cluster is elongated along PA $\approx 50$; however it appears as ``linear'' when taking into account only galaxies in the very central part (the axial ratio varies from 0.2 in the central region to 0.8 for a larger region). We have obtained the galaxy and X-ray emitting gas density profiles and estimated the X-ray gas and dynamical masses. At smaller scales, the analysis of both positions and velocities reveals the existence of several groups; a main structure with a nearly gaussian velocity distribution is exhibited. The velocity dispersion is small ($\sigma_{los}$ = 360 \kms). A wavelet analysis of the X-ray image reveals no large scale substructures. Small scale X-ray sources are detected, mainly corresponding to individual galaxies. ABCG 194 is overall a poor and cold relaxed cluster. We compare how its characteristics fit into various correlations found in the literature, but generally for richer/hotter clusters.Comment: Accepted for publication in Astronomy & Astrophysic

Stellar populations in superclusters of galaxies

A catalogue of superclusters of galaxies is used to investigate the influence of the supercluster environment on galaxy populations, considering galaxies brighter than M$_r<$-21+5$\log$ h. Empirical spectral synthesis techniques are applied to obtain the stellar population properties of galaxies which belong to superclusters and representative values of stellar population parameters are attributed to each supercluster. We show that richer superclusters present denser environments and older stellar populations. The galaxy populations of superclusters classified as filaments and pancakes are statistically similar, indicating that the morphology of superclusters does not have a significative influence on the stellar populations. Clusters of galaxies within superclusters are also examined in order to evaluate the influence of the supercluster environment on their galaxy properties. Our results suggest that the environment affects galaxy properties but its influence should operate on scales of groups and clusters, more than on the scale of superclusters.Comment: 7 pages, 4 figures; accepted to MNRA