Alessia Moretti

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.

Ground-based CCD astrometry with wide field imagers III. WFI@2.2m proper-motion catalog of the globular cluster ω Centauri

Context. ω xa0Centauri is the most well studied Galactic Globular Cluster because of its numerous puzzling features: significant dispersion in metallicity, multiple populations, triple main-sequence, horizontal branch morphology, He-rich population(s), and extended star-formation history. Intensive spectroscopic follow-up observing campaigns targeting stars at different positions in the color–magnitude diagram promises to clarify some of these peculiarities. Aims. To be able to target cluster members reliably during spectroscopic surveys and both spatial and radial distributions in the cluster outskirts without including field stars, a high quality proper-motion catalog of ω xa0Cenxa0and membership probability determination are required. The only available wide field proper-motion catalog of ω xa0Cenxa0is derived from photographic plates, and only for stars brighter than B ~16. Using ESO archive data, we create a new, CCD-based, proper-motion catalog for this cluster, extending to B ~20. Methods. We used high precision astrometric software developed specifically for data acquired by WFI@2.2m telescope and presented in the first paper of this series. We demonstrated previously that a 7xa0mas astrometric precision level can be achieved with this telescope and camera for well exposed stars in a single exposure, assuming an empirical PSF and a local transformation approach in measuring star displacements. Results. We achieved a good cluster-field separation with a temporal base-line of only four years. We corrected our photometry for sky-concentration effects. We provide calibrated photometry for

Age distribution of young clusters and field stars in the Small Magellanic Cloud

UBVR_{rm C}I_{rm C}

The importance of the local density in shaping the galaxy stellar mass functions

wide-band data plus narrow-band filter data centered on H α for almost 360u2009000xa0stars. We confirm that the ω xa0Cenxa0metal-poor and metal-rich components have the same proper motion, and demonstrate that the metal-intermediate component in addition exhibits the same mean motion as the other RGB stars. We provide membership probability determinations for published ω xa0Cenxa0variable star catalogs. Conclusions. Our catalog extends the proper-motion measurements to fainter than the cluster turn-off luminosity, and covers a wide area

WINGS Data Release: a database of galaxies in nearby clusters

({sim}33arcmintimes33arcmin)

The red-sequence of 72 WINGS local galaxy clusters

around the center of ω xa0Cen. Our catalog is electronically available to the astronomical community.

WINGS-SPE III: Equivalent width measurements, spectral properties and evolution of local cluster galaxies. ⋆ ⋆⋆

Aims. In this paper we discuss the cluster and field star formation in the central part of the Small Magellanic Cloud. The main goal is to study the correlation between young objects and their interstellar environment. Methods. The ages of about 164 associations and 311 clusters younger than 1 Gyr are determined using isochrone fitting. The spatial distribution of the clusters is compared with the HI maps, with the HI velocity dispersion field, with the location of the CO clouds and with the distribution of young field stars. Results. The cluster age distribution supports the idea that clusters formed in the last 1 Gyr of the SMC history in a roughly continuous way with periods of enhancements. The two super-shells 37A and 304A detected in the HI distribution are clearly visible in the age distribution of the clusters: an enhancement in the cluster formation rate has taken place from the epoch of the shell formation. A tight correlation between young clusters and the HI intensity is found. The degree of correlation is decreasing with the age of the clusters. Clusters older than 300 Myr are located away from the HI peaks. Clusters and associations younger than 10 Myr are related to the CO clouds in the SW region of the SMC disk. A positive correlation between the location of the young clusters and the velocity dispersion field of the atomic gas is derived only for the shell 304A, suggesting that the cloud-cloud collision is probably not the most important mechanism of cluster formation. Evidence of gravitational triggered episode due to the most recent close interaction between SMC and LMC is found both in the cluster and field star distribution.

The evolution of early-type galaxies in clusters from z∼ 0.8 to z ∼ 0: the ellipticity distribution and the morphological mix

Exploiting the capabilities of four different surveys – the Padova–Millennium Galaxy and Group Catalogue (PM2GC), the WIde-field Nearby Galaxy-cluster Survey (WINGS), the IMACS (Inamori-Magellan Areal Camera and Spectrograph) Cluster Building Survey (ICBS) and the ESO (European Southern Observatory) Distant Cluster Survey (EDisCS) – we analyse the galaxy stellarmass distribution as a function of local density in mass-limited samples, in the field and in clusters from low (z ≥ 0.04) to high (z ≤ 0.8) redshift. We find that at all redshifts and in all environments, local density plays a role in shaping themass distribution. In the field, it regulates the shape of the mass function at any mass above the mass limits. In clusters, it seems to be important only at low masses (log M_∗/M_☉ ≤ 10.1 in WINGS and log M_∗/M_☉ ≤ 10.4 in EDisCS), otherwise it seems not to influence the mass distribution. Putting together our results with those of Calvi et al. and Vulcani et al. for the global environment, we argue that at least at z ≤ 0.8 local density is more important than global environment in determining the ngalaxy stellar mass distribution, suggesting that galaxy properties are not much dependent on halo mass, but do depend on local scale processes.

The jet of the BL Lacertae object PKS 0521-365 in the near-IR: MAD adaptive optics observations

Context. To effectively investigate galaxy formation and evolution, it is of paramount importance to exploit homogeneous data for large samples of galaxies in different environments. Aims. The WIde-field Nearby Galaxy-cluster Survey (WINGS) project aim is to evaluate physical properties of galaxies in a complete sample of low redshift clusters to be used as reference sample for evolutionary studies. The WINGS survey is still ongoing and the original dataset will be enlarged with new observations. This paper presents the entire collection of WINGS measurements obtained so far. Methods. We decided to make use of the Virtual Observatory (VO) tools to share the WINGS database (that will be updated regularly) with the community. In the database each object has one unique identification (WINGSID). Each subset of estimated properties is accessible using a cone search (including wide-field images). Results. We provide the scientific community with the entire set of wide-field images. Furthermore, the published database contains photometry of 759 024 objects and surface brightness analysis for 42 275 and 41 463 galaxies in the V and B band, respectively. The completeness depends on the image quality, and on the cluster redshift, reaching on average 90% at V 21.7. Near-infrared photometric catalogs for 26 (in K) and 19 (in J) clusters are part of the database and the number of sources is 962 344 in K and 628 813 in J. Here again the completeness depends on the data quality, but it is on average higher than 90% for J 20. 5a ndK 19.4. The IR subsample with a Sersic fit comprises 71 687 objects. A morphological classification is available for 39 923 galaxies. We publish spectroscopic data, including 6132 redshifts, 5299 star formation histories, and 4381 equivalent widths. Finally, a calculation of local density is presented and implemented in the VO catalogs for 66 164 galaxies. The latter is presented here for the first time.

GASP. I. Gas Stripping Phenomena in Galaxies with MUSE

The Niels Bohr Institute, Juliane Maries Vej 30, 2100 Copenhagen, DenmarkSeptember 20, 2011ABSTRACTWe study the color-magnitude red sequence and blue fractionof 72 X-ray selected galaxy clusters atz = 0.04−0.07 from the WINGSsurvey, searching for correlations between the characteristics of the red sequence and the environment. We consider the slope andscatter of the red sequence, the number ratio of red luminous-to-faint galaxies, the blue fraction and the fractions of ellipticals, S0sand spirals that compose the red sequence. None of these quantities correlate with the cluster velocity dispersion, X-ray luminosity,number of cluster substructures, BCG prevalence over next brightest galaxies and spatial concentration of ellipticals. Instead, theproperties of the red sequence depend strongly on local galaxy density. Higher density regions have a lower RS scatter, a higherluminous-to-faint ratio, a lower blue fraction, and a lowerspiral fraction on the RS. Our results highlight the prominent effect of thelocal density in setting the epoch when galaxies become passive and join the red sequence, as opposed to the mass of the galaxy hoststructure.Key words. Surveys – Galaxies : Clusters : General – Galaxies: evolutio n – Galaxies: star formation – Galaxies: structure