Catálogo de publicaciones - libros

Color gradients in galaxies reveal information about the nature of their stellar populations via age and metallicity trends, and the amount and distribution of dust in their primary constituents. In this study (see [1]), we use a large catalog of galaxy colors to revisit the comparison of broad-band color gradients with stellar population models using a range of star formation histories (SFH) and basic assumptions about the dust distribution. We follow the approach developed by [2], exploring additional parameter ranges and using an extended data base. Trends in the measured local and global luminosity-weighted age and metallicities and their gradients with galaxy parameters are explored and interpreted in the context of existing models of galaxy formation and evolution.

The unprecedented sky coverage and photometric uniformity of the Two Micron All Sky Survey (2MASS) [1] provides a rich resource for obtaining an understanding of the galaxies populating the local Universe. Characterizing the large-scale clustering distribution is important for theoretical studies of structure formation. 2MASS offers an all-sky view at two microns, unbiased by young stellar light and minimally affected by dust. We use 2MASS to measure the clustering dipole in the band and compare this to the velocity of the Local Group as measured by the CMB dipole [2]. We also measure the angular correlation function and from this infer the K-band three dimensional power spectrum [3].

In order to understand the fueling mechanism to power AGNs, a large effort has been done by the DEGAS (Dynamics and nuclear Engine of GAlaxies of Spiral type) consortium to collect the necessary observational material. We defined an AGN sample which is not contaminated by interacting galaxies and a control sample made of normal spirals with the same properties than the AGN sample, i.e. luminosity and redshift distribution, morphology and percentage of bars. In total we have analyzed a sample of 17 active galaxies and 16 normal spirals. All the galaxies are isolated with the following criteria: not having a companion within 0.4 Mpc and cz < 500 km/s. We want to stress this aspect of our sample, since claimed differences between active and normal galaxies (Knapen et al. 2000) disappear when the samples are decontaminated of interacting systems.

We performed smoothed particle hydro-dynamical simulations of isolated collapsing triaxial systems initially composed of dark matter (DM) and gas with cooling, shocks, star formation and feedback self-consistently accounted for. The initial configuration is built up as expected in the CDM scenario. We analyze the role of the initial geometry, dynamical state and mass of the DM halo on the galaxy formation and evolution. We find intriguing connections between dark and luminous matter. Multiwavelength maps shed light into different galaxy properties.

We present the 60 m luminosity function (LF) of the deepest complete IRAS selected sample [1] so far available, in the North Ecliptic Polar Region (NEPR). The LF here is the first step in the multi-wavelength study of this sample which, thanks to our ISOCAM observations, provides a direct link between IRAS and ISOCAM surveys and the forthcoming deeper SIRTF cosmological surveys. The sample is unique in allowing a direct investigation of the evolution of the global Spectral Energy Distribution (SED) of dusty galaxies up to a redshift of about 0.3, where the global star formation rate is known to evolve very fast.

The strong correlation observed between black-hole and bulge mass in the local Universe (eg. Magorrian et al. 1998; Gebhardt et al. 2000) directly implies that the evolution of the supermassive black holes and their host galaxies are intimately related. In this proceedings we present one of the main results of our recent paper (McLure & Dunlop 2003) which analyses the evolution of quasar black-hole masses drawn from the Sloan Digital Sky Survey (SDSS) first data release (Schneider et al. 2003).

We study Tully–Fisher relation for a sample of 7 cluster spiral galaxies at = 0.83 and 19 field spirals at = 0.15–0.90 based on VLT spectroscopy and HST photometry. No strong difference is detected between the cluster and the field galaxies, but we find some evidence that the cluster spirals are ~ 0.5–1 mag brighter in the rest-frame -band than the field ones at a fixed rotation velocity. Although only a ~ 1.5–2 result, if confirmed with larger samples this effect could be due to the cluster spirals experiencing a period of enhanced star formation while falling into the cluster. The Tully–Fisher residuals for the cluster spirals are found to correlate with the star formation rate, which supports the above hypothesis.

This project is aimed at studying the chemical evolution of bulges of spiral galaxies, with the goals to understand how much the properties of bulges differ from those of elliptical galaxies and to assess if the environment plays a significant role in the chemical evolution. To achieve these goals, we observed 11 spiral galaxies in field and 9 in the Fornax, Hydra and Pegasus cluster. A second run has been completed in September 2003 to complement the cluster sample with 10 additional galaxies. We measured the main Lick indexes H, Mg, Fe, MgFe and the velocity dispersion as function of the galactocentric radius, in order to determine the age and chemical abundances for bulges of galaxies with morphological type ranging from S0 to Sc. Here we present first preliminary results.

The X-ray cluster C0337-2522 at redshift  = 0.59 hosts in its core a group of five elliptical galaxies. Using N-body simulations we show that a multiple merging event among the five galaxies is expected to take place in the next few Gyrs, forming a central brightest cluster galaxy. We also find indications that dynamical friction heating associated with this event is likely to modify the central slope of the cluster dark matter density profile.

The evolution of the properties of galaxy populations with redshift provides important constraints on current models of galaxy formation and evolution. In order to investigate this evolution we used the FORS instruments at the VLT to obtain high-S/N galaxy spectra at redshifts up to 5.0 in the FORS Deep Field (FDF). A detailed discussion of the project can be found in [4].