Publications (7)4.9 Total impact
-
Article: The GALEX Ultraviolet Virgo Cluster Survey (GUViCS). I: The UV luminosity function of the central 12 sq.deg
[show abstract] [hide abstract]
ABSTRACT: The GALEX Ultraviolet Virgo Cluster Survey (GUViCS) is a complete blind survey of the Virgo cluster covering about 40 sq. deg. in the far UV (FUV, lambda_eff=1539A, Delta-lambda=442A) and about 120 sq. deg. in the near UV (NUV, lambda_eff=2316A, Delta-lambda=1060A). The goal of the survey is to study the ultraviolet (UV) properties of galaxies in a rich cluster environment, spanning a wide luminosity range from giants to dwarfs, and regardless of prior knowledge of their star formation activity. The UV data will be combined with those in other bands (optical: NGVS; far-infrared - submm: HeViCS; HI: ALFALFA) and with our multizone chemo-spectrophotometric models of galaxy evolution to make a complete and exhaustive study of the effects of the environment on the evolution of galaxies in high density regions. We present here the scientific objectives of the survey, describing the observing strategy and briefly discussing different data reduction techniques. Using UV data already in-hand for the central 12 sq. deg. we determine the FUV and NUV luminosity functions of the Virgo cluster core for all cluster members and separately for early- and late-type galaxies and compare it to the one obtained in the field and other nearby clusters (Coma, A1367). This analysis shows that the FUV and NUV luminosity functions of the core of the Virgo clusters are flatter (alpha about -1.1) than those determined in Coma and A1367. We discuss the possible origin of this difference02/2011; -
Article: Voids in the 2dFGRS and ΛCDM simulations: spatial and dynamical properties
[show abstract] [hide abstract]
ABSTRACT: We perform a statistical study on the distribution and dynamics of voids in the 2dF Galaxy Redshift Survey (2dFGRS). Our statistics are tested and calibrated using mock 2dFGRS catalogues. We analyse the dynamics around voids in mock and real 2dFGRS surveys. The void–galaxy cross-correlation redshift-space distortions show evidence of the continuing growth of voids, confirming another prediction of the hierarchical clustering scenario. A non-linear outflow model can be used to provide quantitative estimates of the outflow velocities around 2dFGRS voids. These results are consistent with maximum outflows of 110, 210 and 270 km s−1 for voids of 〈rvoid〉= 7.5, 12.5 and 17.5 Mpc h−1, assuming a galaxy bias of b= 1. As an application for future surveys, our study of the mock catalogues shows that direct measurements of the expansion of voids can be obtained using peculiar velocity data. We find that it would also be possible to detect differences in the velocity dispersion of galaxies in the directions parallel and perpendicular to the void walls.Monthly Notices of the Royal Astronomical Society 12/2006; 373(4):1440 - 1450. · 4.90 Impact Factor -
Article: Voids in the 2dFGRS and $Lambda$CDM simulations: spatial and dynamical properties
mnras. 12/2006; 373:1440-1450. -
Article: Galaxy Peculiar Velocities and Infall onto Groups
[show abstract] [hide abstract]
ABSTRACT: We perform statistical analyses to study the infall of galaxies onto groups and clusters in the nearby Universe. The study is based on the UZC and SSRS2 group catalogs and peculiar velocity samples. We find a clear signature of infall of galaxies onto groups over a wide range of scales 5 h^{-1} Mpc<r<30 h^{-1} Mpc, with an infall amplitude on the order of a few hundred kilometers per second. We obtain a significant increase in the infall amplitude with group virial mass (M_{V}) and luminosity of group member galaxies (L_{g}). Groups with M_{V}<10^{13} M_{\odot} show infall velocities V_{infall} \simeq 150 km s^{-1} whereas for M_{V}>10^{13} M_{\odot} a larger infall is observed, V_{infall} \simeq 200 km s^{-1}. Similarly, we find that galaxies surrounding groups with L_{g}<10^{15} L_{\odot} have V_{infall} \simeq 100 km s^{-1}, whereas for L_{g}>10^{15} L_{\odot} groups, the amplitude of the galaxy infall can be as large as V_{infall} \simeq 250 km s^{-1}. The observational results are compared with the results obtained from mock group and galaxy samples constructed from numerical simulations, which include galaxy formation through semianalytical models. We obtain a general agreement between the results from the mock catalogs and the observations. The infall of galaxies onto groups is suitably reproduced in the simulations and, as in the observations, larger virial mass and luminosity groups exhibit the largest galaxy infall amplitudes. We derive estimates of the integrated mass overdensities associated with groups by applying linear theory to the infall velocities after correcting for the effects of distance uncertainties obtained using the mock catalogs. The resulting overdensities are consistent with a power law with \delta \sim 1 at r \sim 10 h^{-1}Mpc. Comment: 25 pages, 10 figures09/2005; -
Article: The faint-end of the galaxy luminosity function in groups
[show abstract] [hide abstract]
ABSTRACT: We compute the galaxy luminosity function in spectroscopically selected nearby groups and clusters. Our sample comprises 728 systems extracted from the third release of the Sloan Digital Sky Survey in the redshift range $0.03 < z < 0.06$ with virial mass range $10^{11}M_\odot < M_{vir} < 2\times 10^{14}M_\odot$. In order to compute the galaxy luminosity function, we apply a statistical background subtraction method following usually adopted techniques. In the $r$ band, the composite galaxy luminosity function shows a slope $\alpha=-1.3$ in the bright--end, and an upturn of the slope in the faint--end, $M_r\ga -18+5log(h)$, to slopes $-1.9<\alpha<-1.6$. We find that this feature is present also in the $i,g$ and $z$ bands, and for all explored group subsamples, irrespective of the group mass, number of members, integrated color or the presence of a hot intra-cluster gas associated to X-ray emission. Comment: 8 pages, 10 figures, Submitted to Astronomy and Astrophysics07/2005; -
Article: Analysis of density profiles of clusters of galaxies.
[show abstract] [hide abstract]
ABSTRACT: The authors perform a statistical analysis of the galaxy density profiles of clusters of galaxies. They consider all clusters of galaxies with published redshifts z < 0.12 in the area covered by the COSMOS/UKST Southern Sky Galaxy Catalogue. The results of the statistical analysis indicate that a single power-law model provides a very good fit to the data. Cluster density profiles are found consistent with an isothermal model with a weak tendency toward flatter profiles for richer objects.01/1996; -1:597-598. -
Article: Dinámica en los entornos a grupos de galaxias
[show abstract] [hide abstract]
ABSTRACT: In this work we have performed a study of the infall of galaxies onto groups in the near universe assuming the spherical infall model (J. P. E. Peebles, The Large Scale Structure of the Universe, 1980; A. Yahil, The Virgo Cluster of Galaxies, 1985). The statistical analysis consisted in the study of galaxy dynamics in groups of external regions. The observational data were obtained from Giovanelli & Haynes (2003) peculiar velocities catalog, the updated Zwicky Catalog and Sky South Redshift Survey 2 groups catalogs (Ramella et. al, A.J. vol. 123 pag. 2676, 2002). We have obtained the mean galaxy infall velocity as a function of distance to the UZC/SSRS2 group centers. The results were compared with the theory of infall velocities derived from the model. We find that it gives an accurate description of the velocity field in a large scale range between 4 and 20 Mpc/h. Similar analyses were performed for mock catalogs specially designed to confront models to observations. We obtained a good agreement between the results of both catalogs. We investigated the existence of same entail beetwen virial mass and the mass overdensity. We studied the infall of mass particles to the haloes in the simulations and we compared with the infall of galaxies onto the groups in the mock catalogs. We obtain similar results which indicate that galaxies and mass have the same dynamical behavior in these regions.Boletin de la Asociacion Argentina de Astronomia La Plata Argentina. 46:92-93.
