Catálogo de publicaciones - libros

Large scale structures can bias global measurements, such as the star formation history, due to over and under densities in the field at a given redshift. To overcome this problem large area redshift surveys are necessary. Photometric redshifts provide an economical method for estimating the distances to galaxies using the broad band photometry. To this end we are surveying 1.2 sq. degrees centered on the Hawaii survey fields in U, B, V, R, I, z’, J, HK’ to depths similar to the Great Observatories Origins Deep Survey (GOODS). Many of these fields have also been observed in the x-ray, sub-mm, and radio and will be observed with SIRTIF in the near future. Using, our data in the Hawaii Hubble Deep Field North (Hawaii HDF-N) and SSA22, we have obtained photometric redshifts accurate to dz/(1+z)=0.06. These can then be used to measure the global star formation history and the evolution of Active Galactic Nuclei (AGN).

We present the photometric redshift distribution of a sample of 198 Extremely Red Galaxies (ERGs) with K < 22 and (I – K) > 3.92 (Vega), selected by Roche et al. [3] in 50.4 arcmin of the Chandra Deep Field South (CDFS). The sample has been obtained using ISAAC-VLT and ACS-HST GOODS public data. We also show the results of a morphological study of the 72 brightest ERGs in the z band (z < 25, AB).

The study of the stellar populations of the elliptical galaxies in compact groups could give us important information on the merging history of the elliptical galaxies in the groups and could elucidate some of the questions regarding group evolution. We have initiated a program to study the stellar populations of the elliptical galaxies in compact groups. In the following, we describe our results for a sample of 12 galaxies. The kinematical properties of the same sample were previously studied by Mendes de Oliveira et al. (1993).

We studied the SB0 galaxy NGC 2950, which hosts two nested stellar bars. We used the Tremaine-Weinberg method to measure the pattern speed of the primary bar. We established directly and for the first time in a double-barred galaxy that the two nested bars are rotating with different pattern speeds.

The peculiar ring galaxies are formed as a result of cosmic interaction. An intruder galaxy plunges through the center of a disk galaxy triggering radially expanding density waves on the disk. Here we present results of SPH simulations which focus on the role of different halos (live and analytical) and bulges on the morphology of the target galaxy and on the star formation rate. We find that inside a live triaxial halo arise unfavourable conditions to the development of a ring. Moreover, for same collision, different features appear if the target galaxy is embedded in an analytical halo or endowed with a massive bulge. The presence of a bulge noticeably affects the star formation rate and the dynamical evolution of the interacting system.

We present evidence for star formation in distant radio galaxies based on deep FORS1/VLT spectropolarimetry and SCUBA/JCMT 850m photometry.

We present preliminary results from H spectroscopy and deep -band imaging of UV-selected star-forming galaxies at ~2. We see evidence for relatively mature, massive galaxies in the form of an increase in the mean velocity dispersion and the mean color from ~3 to ~2, and in the approximately solar metallicities of a significant number of the ~2 galaxies. There appears to be substantial diversity in the ~2 sample, as other kinematic measurements suggest that some of the galaxies are still in the process of formation.

Ground based and HST imaging of quasars (see, e.g., Dunlop et al. 2003; Pagani et al. 2003 and references therein) clearly indicate that at z < 0.5 quasars are hosted in massive galaxies dominated by the spheroidal component. While radio loud quasars (RLQ) are exclusively hosted by ellipticals exceeding by 2–3 mag L*, radio quiet quasars (RQQ) are found both in ellipticals and in spirals. On the other hand there is mounting evidence that most if not all nearby massive spheroids have inactive supermassive BH in their centers (see e.g. Ferrarese 2002 for a review). Taken together these findings depict a scenario where nuclear activity may be a common phenomenon during the lifetime of a galaxy. Understanding how the properties of the galaxies hosting quasars change with the cosmic time is therefore a fundamental step to investigate the link between the evolution of the galaxies and the nuclear activity.

The GOODS Team [2] presented a sample of 17 high-redshift QSO candidates from the GOODS fields with 3.5 <  < 5.2. The number counts of their  > 4 quasar revealed a dearth of low-luminosity objects both with respect to naive Pure Luminosity Evolution (PLE) predictions and to models based on the statistic of major mergings of dark matter halos (DMHs) [5]. A Pure Density Evolution (PDE) prediction of the quasar luminosity function (LF) at  ~ 2.7 [1] appeared able to reproduce both the SDSS counts and the GOODS number counts.

Multivariate or multi-wavelength luminosity functions will reveal the interplay between star formation, chemical evolution, and absorption and re-emission of dust within evolving galaxy populations. By using principal component analysis to reduce the dimensionality of the problem, I optimally extract the relevant photometric information from large galaxy catalogs. As a demonstration of the technique, I derive the multi-wavelength luminosity function for the galaxies in the released SDSS catalog, and compare the results with those obtained by traditional methods.