Gustavo Bruzual

SPIDER – VII. Revealing the stellar population content of massive early-type galaxies out to 8Re

Radial trends of stellar populations in galaxies provide a valuable tool to understand the mechanisms of galaxy growth. In this paper, we present the first comprehensive analysis of optical–optical and optical–NIR colours, as a function of galaxy mass, out to the halo region (8Re) of early-type galaxies (ETGs). We select a sample of 674 massive ETGs (M� 3 × 10 10 M� ) from the Sloan Digital Sky Survey (SDSS)-based SPIDER survey. By comparing with a large range of population synthesis models, we derive robust constraints on the radial trends in age and metallicity. Metallicity is unambiguously found to decrease outwards, with a measurable steepening of the slope in the outer regions (Re < R < 8Re). The gradients in stellar age are found to be more sensitive to the models used, but in general, the outer regions of ETGs feature older populations compared to the cores. This trend is strongest for the most massive galaxies in our sample (M� 10 11 M� ). Furthermore, when segregating with respect to large-scale environment, the age gradient is more significant in ETGs residing in higher density regions. These results shed light on the processes leading from the formation of the central core to the growth of the stellar envelope of massive galaxies. The fact that the populations in the outer regions are older and more metal-poor than in the core suggests a process whereby the envelope of massive galaxies is made up of accreted small satellites (i.e. minor mergers) whose stars were born during the first stages of galaxy formation.

Constraining globular cluster formation through studies of young massive clusters – II. A single stellar population young massive cluster in NGC 34

Currently there are two competing scenarios to explain the origin of the stellar population in globular clusters (GCs). The main difference between them is whether or not multiple events of star formation took place within GCs. In this paper we present the star formation history (SFH) of Cluster 1, a massive young cluster in NGC 34

Modelling the nebular emission from primeval to present-day star-forming galaxies

(\sim10^7\mbox{ M}_\odot)

Chemoarchaeological downsizing in a hierarchical universe: impact of a top-heavy IGIMF

. We use DynBaS, a spectrum fitting algorithm, to retrieve the SFH and find that Cluster 1 is consistent with a single stellar population of solar metallicity with an age of

A comprehensive comparative test of seven widely used spectral synthesis models against multi-band photometry of young massive-star clusters

100\pm30

Consequences of bursty star formation on galaxy observables at high redshifts

Myr and a mass of

Is the escape velocity in star clusters linked to extended star formation histories? Using NGC 7252: W3 as a test case

1.9\pm0.4\times10^7\mbox{ M}_\odot

Strong gravitational lensing and the stellar IMF of early-type galaxies

. These results are in conflict with the expectations/predictions of the scenarios that invoke extended or multiple episodes within 30--100 Myr of the initial star-formation burst in young massive clusters.

Variations of the stellar initial mass function in semi-analytical models: implications for the mass assembly and the chemical enrichment of galaxies in the gaea model

We present a new model of the nebular emission from star-forming galaxies in a wide range of chemical compositions, appropriate to interpret observations of galaxies at all cosmic epochs. The model relies on the combination of state-of-the-art stellar population synthesis and photoionization codes to describe the ensemble of H ii regions and the diffuse gas ionized by young stars in a galaxy. A main feature of this model is the self-consistent yet versatile treatment of element abundances and depletion on to dust grains, which allows one to relate the observed nebular emission from a galaxy to both gas-phase and dust-phase metal enrichment. We show that this model can account for the rest-frame ultraviolet and optical emission-line properties of galaxies at different redshifts and find that ultraviolet emission lines are more sensitive than optical ones to parameters such as C/O abundance ratio, hydrogen gas density, dust-to-metal mass ratio and upper cut-off of the stellar initial mass function. We also find that, for gas-phase metallicities around solar to slightly subsolar, widely used formulae to constrain oxygen ionic fractions and the C/O ratio from ultraviolet and optical emission-line luminosities are reasonable faithful. However, the recipes break down at non-solar metallicities, making them inappropriate to study chemically young galaxies. In such cases, a fully self-consistent model of the kind presented in this paper is required to interpret the observed nebular emission.

SILVERRUSH. V. Census of Lyα, [O iii] λ5007, Hα, and [C ii] 158 μm Line Emission with ∼1000 LAEs at z = 4.9–7.0 Revealed with Subaru/HSC

Fil: Gargiulo, Ignacio Daniel. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico La Plata. Instituto de Astrofisica de La Plata; Argentina; Argentina. Universidad Nacional de la Plata. Facultad de Ciencias Astronomicas y Geofisicas; Argentina