Catálogo de publicaciones - libros

I summarize the recent results from the HDFS and K20 surveys that allow to trace the evolution of massive galaxies up to ≃ 3. I show that the evolution of both the specific star–formation rate and of the stellar mass density suggest that, at >1, we observe the epoch where the evolution of massive objects becomes appreciable. At ≃ 1.8, we indeed find that about 40% of the local density has been locked in massive galaxies. This is associated with a change in the physical properties of massive galaxies, with star–forming objects that contribute to a substantial fraction of the observed mass density. I quantitatively show that these results do not pose challenges to current - models, but represent valuable constraints to understand the complex physical mechanisms involved in the assembly of massive galaxies.

Luminous Compact Blue Galaxies (LCBGs) are small starburst systems that dominate the number density of galaxies at intermediate redshifts. LCBGs have evolved more than any other galaxy class in the last 8 Gyrs and are a major contributor to the observed enhancement of the UV luminosity density of the universe at < 1. Despite the key role LCBGs may play in galaxy evolution, their statistical properties are still largely unknown. We are currently conducting a multiwavelength study of LCBGs from z = 3 to the present, ranging from FUV to FIR. This study is unique in combining the capabilities of space observatories with ground-based large telescopes and large public databases of galaxy surveys. The main goals of this study are: (i) to characterize the global properties of LCBGs at 0 < < 3 using statistically representative samples defined using the same selection criteria and over the same rest-frame wavelength range; and (ii) to investigate the role of this important population in galaxy formation and evolution.

We report on early results from the Galaxy Evolution Explorer (GALEX), a NASA Explorer Mission launched on April 28, with a nominal mission start of June 19. GALEX is performing the first space UV sky-survey, including imaging and grism surveys in two bands (1350–1750Å and 1750–2800Å). The surveys include an all-sky imaging survey (limit AB~20–21), a medium imaging survey of 1000 sq. deg (limit AB~23.5), a deep imaging survey of 100 square degrees (limit AB~25), and a nearby galaxy survey. Spectroscopic grism surveys (R=100–300) are underway with various depths and sky coverage. Many targets overlap existing or planned surveys. We will use the measured UV properties of local galaxies, along with corollary observations, to calibrate the UV-global star formation rate relationship in galaxies. We will apply this calibration to distant galaxies discovered in the deep imaging and spectroscopic surveys to map the history of star formation in the universe over the redshift range 0<z<2. The GALEX mission will include a Guest Investigator program for primary observations and supporting data analysis. This will support a wide variety of investigations made possible by the first UV sky survey.

The was launched in April 2003 and has returned wide field UV imagery in a far UV (1450A) and near UV (2800A) channel. We report on new results in the study of starbursts and stellar populations. Galex detects light from recently formed massive stars, and also from hot evolved older stars. Combining SDSS and Galex photometry gives a large multiwavelength dataset. Fitting the SEDs to population models in a statistical sense gives constraints on the starburst history of galaxies. Galex is remarkably sensitive to low levels of star formation, some of which is detected in the red sequence of ellipticals and bulges, even to 10 M yr. The UV rising flux is clearly seen in nearby bulges and elliptical, and is also detected to ~ 0.1 in A2670. Constructing a sample of ellipticals selected from SDSS to lack emission lines to appear in all respects “old, red, and dead” we find no correlation between the UV rising flux and the Lick index, or with any other measurable parameter such as velocity dispersion; this finding contradicts some earlier studies.

We describe how optical spectra of =1–2 galaxies can help test the hypothesis of hierarchical galaxy formation.

DEEP has launched DEEP2, a major new Keck spectroscopic survey of 50,000 galaxies at redshift ~ 1 using a new spectrograph (DEIMOS). We give an overview of the project’s science goals and why DEEP2 is especially attractive to support complementary coverage by a suite of faint multiwavelength imaging surveys. We highlight one such effort already underway in the DEEP2 field called the Extended Groth Strip (EGS).

We describe observations focused on understanding the epochs and timescales of the formation and evolution of early-type galaxies, particularly those in clusters. We show that while early-type cluster galaxies are on average older and closer to coeval than their counterparts in the field, significant age spreads (a factor of two in massive ellipticals, more in low-mass galaxies, especially S0’s) still exist in these objects. We then show that it is now possible to detect the evolution of early-type galaxies directly by comparing deep absorption-line spectroscopy of intermediate-redshift cluster galaxies with local cluster galaxies. We find that the stellar populations of early-type cluster galaxies do indeed evolve, at a rate that appears to be consistent with the cosmological lookback time.

Near-infrared surveys provide one of the best opportunities to investigate the cosmic evolution of galaxies and their mass assembly. We briefly review the main results obtained so far with the K20 and other recent near-IR surveys on the redshift distribution, the evolution of the luminosity function and luminosity density, the nature of old and dusty EROs, the evolution of the galaxy stellar mass function, the properties of the galaxies in the “redshift desert” and the nature of luminous starbursts at ~2.

On behalf of the survey teams I summarize the designs and results of the Las Campanas Infrared Survey and Gemini Deep Deep Survey, both of which were initiated to understand the nature of red galaxies and to study the history of stellar mass assembly. Our results from luminosity function analysis, ISM absorption line measurements, and spectral synthesis modeling show that near-infrared selected galaxies at 1<<2 are not only massive and abundant but also old and metal enriched, indicating rapid formation of massive systems at higher redshifts.

MUNICS is a wide-area, medium-deep, photometric and spectroscopic survey selected in the K band, targeting randomly-selected high Galactic latitude fields. It covers an area of roughly one square degree in the K and J bands with complementary optical follow-up imaging in the I, R, V, and B bands in 0.5 square degrees.