T. Valentinuzzi

Superdense Massive Galaxies in Wings Local Clusters

Massive quiescent galaxies at z > 1 have been found to have small physical sizes, and hence to be superdense. Several mechanisms, including minor mergers, have been proposed for increasing galaxy sizes from high- to low-z. We search for superdense massive galaxies in the WIde-field Nearby Galaxy-cluster Survey (WINGS) of X-ray selected galaxy clusters at 0.04 2 study. In contrast, there is strong evidence for a large evolution in radius for the most massive galaxies with M * > 4 × 1011 M ☉ compared to similarly massive galaxies in WINGS, i.e., the brightest cluster galaxies.

WINGS-SPE Spectroscopy in the WIde-field Nearby Galaxy-cluster Survey

Aims. We present the results from a comprehensive spectroscopic survey of the WINGS (Wide-field Nearby Galaxy-cluster Survey) clusters, a program called WINGS-SPE. The WINGS-SPE sample consists of 48 clusters, 22 of which are in the southern sky and 26 in the north. The main goals of this spectroscopic survey are: (1) to study the dynamics and kinematics of the WINGS clusters and their constituent galaxies, (2) to explore the link between the spectral properties and the morphological evolution in different density environments and across a wide range of cluster X-ray luminosities and optical properties. Methods. Using multi-object fiber-fed spectrographs, we observed our sample of WINGS cluster galaxies at an intermediate resolution of 6-9 A and, using a cross-correlation technique, we measured redshifts with a mean accuracy of ∼45 km s -1 . Results. We present redshift measurements for 6137 galaxies and their first analyses. Details of the spectroscopic observations are reported. The WINGS-SPE has ∼30% overlap with previously published data sets, allowing us both to perform a complete comparison with the literature and to extend the catalogs. Conclusions. Using our redshifts, we calculate the velocity dispersion for all the clusters in the WINGS-SPE sample. We almost triple the number of member galaxies known in each cluster with respect to previous works. We also investigate the X-ray luminosity vs. velocity dispersion relation for our WINGS-SPE clusters, and find it to be consistent with the form L x ∝ σ 4 v .

Galaxy stellar mass functions of different morphological types in clusters, and their evolution between z= 0.8 and 0

We present the galaxy stellar mass function and its evolution in clusters from z ∼ 0.8 to the current epoch, based on the WIde-field Nearby Galaxy-cluster Survey (WINGS) (0.04 ≤ z ≤ 0.07), and the ESO Distant Cluster Survey (EDisCS) (0.4 ≤ z ≤ 0.8). We investi- gate the total mass function and find that it evolves noticeably with redshift. The shape at M∗ > 10 11 Mdoes not evolve, but below M∗ ∼ 10 10.8 Mthe mass function at high red- shift is flat, while in the local Universe it flattens out at lower masses. The population of M∗ = 10 10.2 -10 10.8 Mgalaxies must have grown significantly between z = 0.8 and 0. We analyse the mass functions of different morphological types (ellipticals, S0s and late types), and also find that each of them evolves with redshift. All types have proportionally more massive galaxies at high than at low-z, and the strongest evolution occurs among S0 galaxies. Examining the morphology-mass relation (the way the proportion of galaxies of different morphological types changes with galaxy mass), we find it strongly depends on redshift. At both redshifts, ∼40 per cent of the stellar mass is in elliptical galaxies. Another ∼43 per cent of the mass is in S0 galaxies in local clusters, while it is in late types in distant clusters. To explain the observed trends, we discuss the importance of those mechanisms that could shape the mass function. We conclude that mass growth due to star formation plays a crucial role in driving the evolution. It has to be accompanied by infall of galaxies on to clusters, and the mass distribution of infalling galaxies might be different from that of cluster galaxies. However, comparing with high-z field samples, we do not find conclusive evidence for such an environmental mass segregation. Our results suggest that star formation and infall change directly the mass function of late-type galaxies in clusters and, indirectly, that of early-type galaxies through subsequent morphological transformations.

The evolution of spiral, S0 and elliptical galaxies in clusters

We quantify the evolution of the spiral, S0 and elliptical fractions in galaxy clusters as a function of cluster velocity dispersion (σ) and X-ray luminosity (LX ) using a new database of 72 nearby clusters from the Wide-Field Nearby Galaxy-Cluster Survey (WINGS) combined with literature data at z = 0.5-1.2. Most WINGS clusters have σ between 500 and 1100 km s–1, and LX between 0.2 and 5 × 1044 erg s–1. The S0 fraction in clusters is known to increase with time at the expense of the spiral population. We find that the spiral and S0 fractions have evolved more strongly in lower σ, less massive clusters, while we confirm that the proportion of ellipticals has remained unchanged. Our results demonstrate that morphological evolution since z = 1 is not confined to massive clusters, but is actually more pronounced in low-mass clusters, and therefore must originate either from secular (intrinsic) evolution and/or from environmental mechanisms that act preferentially in low-mass environments, or both in low- and high-mass systems. We also find that the evolution of the spiral fraction perfectly mirrors the evolution of the fraction of star-forming galaxies. Interestingly, at low-z the spiral fraction anticorrelates with LX . Conversely, no correlation is observed with σ. Given that both σ and LX are tracers of the cluster mass, these results pose a challenge for current scenarios of morphological evolution in clusters.

Superdense massive galaxies in the ESO Distant Cluster Survey (EDisCS)

We find a significant number of massive and compact galaxies in clusters from the ESO Distant Clusters Survey (EDisCS) at 0.4 < z < 1. They have similar stellar masses, ages, sizes and axial ra tios to local z � 0.04 compact galaxies in WINGS clusters, and to z = 1.4 - 2 massive and passive galaxies found in the general field. If non-BCG cluster galaxies of all densities, morphol ogies and spectral types are considered, the median size of EDisCS galaxies is only a factor 1.18 smaller than in WINGS. We show that for morphologically selected samples, the morphological evolution taking place in a significant fraction of galaxies during the last Gyrs may introduce an apparent, spurious evolution of size with redshift, which is actually due to intrinsic differences in the selected samples. We conclude that the median mass-size relation of cluster galaxies does not evolve significantly from z � 0.7 to z � 0.04. In contrast, the masses and sizes of BCGs and galaxies with

The fundamental plane of EDisCS galaxies - the effect of size evolution

We study the evolution of spectral early-type galaxies in clusters, groups, and the field up to redshift 0.9 using the ESO Distant Cluster Survey (EDisCS) dataset. We measure structural parameters (circularized half-luminosity radii Re, surface brightness Ie, and velocity dispersions σ )f or 154 cluster and 68 field galaxies. On average, we achieve precisions of 10% in Re ,0 .1 dex in logIe, and 10% in σ .W e sample≈20% of cluster and ≈10% of field spectral early-type galaxies to an I band magnitude in a 1 arcsec radius aperture as faint as I1 = 22. We study the evolution of the zero point of the fundamental plane (FP) and confirm results in the literature, but now also for the low cluster velocity dispersion regime. Taken at face value, the mass-to-light ratio varies as Δ log M/LB = (−0.54 ± 0.01)z = (−1.61 ± 0.01) log(1 + z) in clusters, independent of their velocity dispersion. The evolution is stronger (Δ log M/LB = (−0.76 ± 0.01)z = (−2.27 ± 0.03) log(1 + z)) for field galaxies. A somewhat milder evolution is derived if a correction for incompleteness is applied. A rotation in the FP with redshift is detected with low statistical significance. The α and β FP coefficients decrease with redshift, or, equivalently, the FP residuals correlate with galaxy mass and become progressively negative at low masses. The effect is visible at z ≥ 0.7 for cluster galaxies and at lower redshifts z ≥ 0.5 for field galaxies. We investigate the size evolution of our galaxy sample. In agreement with previous results, we find that the half-luminosity radius for a galaxy with a dynamical or stellar mass

The Evolution of the Number Density of Compact Galaxies

We compare the number density of compact (small size) massive galaxies at low and high redshift using our Padova Millennium Galaxy and Group Catalogue (PM2GC) at z = 0.03-0.11 and the CANDELS results from Barro et al. at z = 1-2. The number density of local compact galaxies with luminosity weighted (LW) ages compatible with being already passive at high redshift is compared with the density of compact passive galaxies observed at high-z. Our results place an upper limit of a factor ~2 on the evolution of the number density and are inconsistent with a significant size evolution for most of the compact galaxies observed at high-z. Instead, the evolution may be significant (up to a factor five) for the most extreme, ultracompact galaxies. Considering all compact galaxies, regardless of LW age and star formation activity, a minority of local compact galaxies (≤1/3) might have formed at z < 1. Finally, we show that the secular decrease of the galaxy stellar mass due to simple stellar evolution may in some cases be a non-negligible factor in the context of the evolution of the mass-size relation, and we caution that passive evolution in mass should be taken into account when comparing samples at different redshifts.

WINGS-SPE II: A catalog of stellar ages and star formation histories, stellar masses and dust extinction values for local clusters galaxies

Context. The WIde-field Nearby Galaxy clusters Survey (wings) is a project whose primary goal is to study the galaxy populations in clusters in the local universe (z < 0.07) and of the influence of environment on their stellar populations. This survey has provided the astronomical community with a high quality set of photometric and spectroscopic data for 77 and 48 nearby galaxy clusters, respectively. Aims. In this paper we present the catalog containing the properties of galaxies observed by the wings SPEctroscopic (WINGS-SPE) survey, which were derived using stellar populations synthesis modelling approach. We also check the consistency of our results with other data in the literature. Methods. Using a spectrophotometric model that reproduces the main features of observed spectra by summing the theoretical spectra of simple stellar populations of different ages, we derive the stellar masses, star formation histories, average age and dust attenuation of galaxies in our sample. Results. similar to 5300 spectra were analyzed with spectrophotometric techniques, and this allowed us to derive the star formation history, stellar masses and ages, and extinction for the wings spectroscopic sample that we present in this paper. Conclusions. The comparison with the total mass values of the same galaxies derived by other authors based on sdss data, confirms the reliability of the adopted methods and data.

WINGS: a WIde-field nearby Galaxy-cluster survey III: deep near-infrared photometry of 28 nearby clusters

Context. This is the third paper in a series devoted to the WIde-field Nearby Galaxy-cluster Survey (WINGS). WINGS is a long-term project aimed at gathering wide-field, multiband imaging and spectroscopy of galaxies in a complete sample of 77 X-ray selected, nearby clusters (0.04 < z < 0.07) located far from the galactic plane (|b |≥ 20 ◦ ). The main goal of this project is to establish a local reference sample for evolutionary studies of galaxies and galaxy clusters. Aims. This paper presents the near-infrared (J,K) photometric catalogs of 28 clusters of the WINGS sample and describes the procedures followed to construct them. Methods. The raw data has been reduced at CASU and special care has been devoted to the final coadding, drizzling technique, astrometric solution, and magnitude calibration for the WFCAM pipeline-processed data. We constructed the photometric catalogs based on the final calibrated, coadded mosaics (≈0.79 deg 2 )i nJ (19 clusters) and K (27 clusters) bands. A customized interactive pipeline was used to clean the catalogs and to make mock images for photometric errors and completeness estimates. Results. We provide deep near-infrared photometric catalogs (90% complete in detection rate at total magnitudes J ≈ 20.5, K ≈ 19.4, and in classification rate at J ≈ 19. 5a ndK ≈ 18.5), giving positions, geometrical parameters, total and aperture magnitudes for all detected sources. For each field we classify the detected sources as stars, galaxies, and objects of “unknown” nature.

The shapes of BCGs and normal ellipticals in nearby clusters

We compare the apparent axial ratio distributions of the brightest cluster galaxies (BCGs) and normal ellipticals (Es) in our sample of 75 galaxy clusters from the WIde-field Nearby Galaxy-cluster Survey (WINGS). Most BCGs in our clusters (69 per cent) are classified as cD galaxies. The sample of cDs has been completed by 14 additional cDs (non-BCGs) we found in our clusters. We deproject the apparent axial ratio distributions of Es, BCGs and cDs using a bivariate version of the Lucy rectification algorithm, whose results are supported by an independent Monte Carlo technique. Finally, we compare the intrinsic shape distribution of BCGs to the corresponding shape distribution of the central part of cluster-sized dark matter haloes extracted from the GIF2 Lambda cold dark matter (ΛCDM) N-body simulations (Gao et al.). We find that (i) Es have triaxial shape, the triaxiality sharing almost evenly the intrinsic axial ratio parameter space, with a weak preference for prolateness and (ii) the BCGs have triaxial shape as well. However, their tendency towards prolateness is much stronger than in the case of Es. Such a strong prolateness appears entirely due to the sizeable (dominant) component of cDs inside the WINGS sample of BCGs. In fact, while the ‘normal’ (non-cD) BCGs do not differ from Es, as far as the shape distribution is concerned, the axial ratio distribution of BCG_cD galaxies is found to support quite prolate shapes; (iii) our result turns out to be strongly at variance with the only similar previous analysis by Ryden, Lauer & Postman (RLP93), where BCGs and Es were found to share the same axial ratio distribution; (iv) our data suggest that the above discrepancy is mainly caused by the different criteria that RLP93 and ourselves use to select the cluster samples, coupled with a preference of cDs to reside in powerful X-ray-emitting clusters; (v) the GIF2 N-body results suggest that the prolateness of the BCGs (in particular the cDs) could reflect the shape of the associated dark matter haloes.