F. La Barbera

Astronomical Observatory of Capodimonte

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G. Busarello

Astronomical Observatory of Capodimonte

P. Merluzzi

Astronomical Observatory of Capodimonte

A. Vazdekis

Universidad de La Laguna

Ignacio Ferreras

Instituto de Astrofísica de Canarias

N. R. Napolitano

University of Naples Federico II

C. Tortora

Astronomical Observatory of Capodimonte

R. R. de Carvalho

Universidade Cruzeiro do Sul

M. Capaccioli

Federico II University Hospital

A. Mercurio

Ospedale San Bassiano

C. P. Haines

Brera Astronomical Observatory

Cooperative Institutions

National Institute for Astrophysics

137

Max Planck Society

103

Centre National de la Recherche Scientifique

Max Planck Institute for Astronomy

Instituto de Astrofísica de Canarias

Leiden University

European Southern Observatory

Astronomical Observatory of Capodimonte

Universidad de La Laguna

University College London

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Young stellar populations from NUV spectroscopy in massive early-type galaxies

Contributions to the XIV.0 Scientific Meeting (virtual) of the Spanish Astronomical Society (2020)

Núria Salvador Rusiñol A. Vazdekis M. A. Beasley F. La Barbera Ignacio Ferreras

Stellar population

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VEGAS-SSS. A VST early-type galaxy survey: analysis of small stellar systems

Astronomy and Astrophysics (2014)

Michele Cantiello Massimo Capaccioli N. R. Napolitano A. Grado L. Limatola

We present a study of globular clusters (GCs) and other small stellar systems (SSSs) in the field of NGC3115, observed as part of the VEGAS imaging survey, carried out with the VST telescope. We use deep g and i data of NGC3115, a well-studied lenticular galaxy with excellent scientific literature. This is fundamental to test the methodologies, verify the results, and probe the capabilities of the VEGAS-SSS. Leveraging the large field of view of the VST allow us to accurately study of the distribution and properties of SSSs as a function of galactocentric distance Rgc, well beyond ~20 galaxy effective radii, in a way not often possible. Our analysis of colors, magnitudes and sizes of SSS candidates confirms the results from existing studies, some of which carried out with 8-10m class telescopes, and further extends them to unreached Rgc distances, with similar accuracy. We find a color bimodality for the GC population and a r1/4 profile for the surface density of GCs as for the galaxy light profile. The radial color gradient of blue and red GCs previously found, for instance by the SLUGGS survey, is further extended out to the largest Rgc inspected, ~65 kpc. The surface density profiles of blue and red GCs taken separately are well approximated by a r1/4 density profile, with the fraction of blue GCs being slightly larger at larger Rgc. We do not find hints of a trend for the red GC and for the GC turnover magnitude to vary with radius, but we observe a ~0.2 mag difference in the turnover magnitude of the blue and red GCs subpopulations. Inspecting SSS sizes and colors we obtained a list of UCDs and GC candidates suitable for future spectroscopic follow-up. In conclusion, our study shows the reliability of the methodologies developed to study SSSs in the field of bright early-type galaxies, and the great potential of the VEGAS survey to produce original results on SSSs science.

Bimodality

Effective radius

Stellar population

10.1051/0004-6361/201425165

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Citations (17)

Abundance ratios and IMF slopes in the dwarf elliptical galaxy NGC 1396 with MUSE

Monthly Notices of the Royal Astronomical Society (2016)

J. J. Mentz F. La Barbera R. F. Peletier J. Falcón‐Barroso T. Lisker

Deep observations of the dwarf elliptical (dE) galaxy NGC 1396 (M$_V = -16.60$, Mass $\sim 4\times10^8$ M$_\odot$), located in the Fornax cluster, have been performed with the VLT/ MUSE spectrograph in the wavelength region from $4750-9350$ \AA{}. In this paper we present a stellar population analysis studying chemical abundances, the star formation history (SFH) and the stellar initial mass function (IMF) as a function of galacto-centric distance. Different, independent ways to analyse the stellar populations result in a luminosity-weighted age of $\sim$ 6 Gyr and a metallicity [Fe/H]$\sim$ $-0.4$, similar to other dEs of similar mass. We find unusually overabundant values of [Ca/Fe] $\sim +0.1$, and under-abundant Sodium, with [Na/Fe] values around $-0.1$, while [Mg/Fe] is overabundant at all radii, increasing from $\sim+0.1$ in the centre to $\sim +0.2$ dex. We notice a significant metallicity and age gradient within this dwarf galaxy. To constrain the stellar IMF of NGC 1396, we find that the IMF of NGC 1396 is consistent with either a Kroupa-like or a top-heavy distribution, while a bottom-heavy IMF is firmly ruled out. An analysis of the abundance ratios, and a comparison with galaxies in the Local Group, shows that the chemical enrichment history of NGC 1396 is similar to the Galactic disc, with an extended star formation history. This would be the case if the galaxy originated from a LMC-sized dwarf galaxy progenitor, which would lose its gas while falling into the Fornax cluster.

Stellar population

Stellar mass

Initial mass function

10.1093/mnras/stw2129

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Citations (37)

Evolution of Uv-Nir Structure of Cluster Galaxies

IAU Joint Discussion (2003)

P. Merluzzi F. La Barbera G. Busarello M. Massarotti

Source

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The elemental abundances of quiescent galaxies in the LEGA-C survey: the (non-)evolution of [α/Fe] from z = 0.75 to z = 0

arXiv (Cornell University) (2023)

Davide Bevacqua P. Saracco F. La Barbera G. D’Ago Roberto De Propris

We measure the [${\alpha}$/Fe] abundances for 183 quiescent galaxies at z = 0.60 - 0.75 with stellar masses ranging 10.4 \leq log10 10.4 $\leq$ log10 (M$_*$ /M$_\odot$) $\leq$ 11.6 selected from the LEGA-C survey. We estimate [${\alpha}$/Fe] from the ratio of the spectral indices Mgb (${\lambda} \sim 5177$ {\AA}) and Fe4383, compared to predictions of simple stellar population models. We find that 91% of quiescents in our sample have supersolar [${\alpha}$/Fe], with an average value of [${\alpha}$/Fe] = +0.24 $\pm$ 0.01. We find no significant correlation between [${\alpha}$/Fe] and stellar metallicity, mass, velocity dispersion, and average formation time. Galaxies that formed the bulk of their stellar mass on time scales shorter than 1 Gyr follow the same [${\alpha}$/Fe] distribution as those which formed on longer time scales. In comparison to local early-type galaxies and to stacked spectra of quiescent galaxies at z = 0.38 and z = 0.07, we find that the average [${\alpha}$/Fe] has not changed between z = 0.75 and the present time. Our work shows that the vast majority of massive quiescent galaxies at z $\sim$ 0.7 are ${\alpha}$-enhanced, and that no detectable evolution of the average [${\alpha}$/Fe] has taken place over the last $\sim$ 6.5 Gyr.

Velocity dispersion

Stellar population

Stellar mass

10.48550/arxiv.2308.03441

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Fitting planes to early-type galaxies: MIST for the determination of the Fundamental Plane

arXiv (Cornell University) (2000)

F. La Barbera G. Busarello M. Capaccioli

The present study deals with the problem of deriving the coefficients of the fundamental plane (FP) of early-type galaxies. We introduce statistical models of the FP and relative fitting methods: the MIST (Measurement errors and Intrinsic Scatter Three dimensional) fits. The MIST fits account for the measurement errors on the variables and their correlations as well as for the intrinsic scatter. We show that the lack of a model of the intrinsic scatter of the FP is the origin of the systematic differences between the various fitting methods. We also address the problem of estimating the uncertainties of the FP coefficients and determine a simple relation between the sample size and the expected accuracy of the coefficients. The present study leads to define a `minimum sample size' for a correct estimate of the uncertainties. For N < 30, both theoretical formulae and re-sampling techniques, like the bootstrap, do not give reliable estimates. The question of the 'universality' of the FP is addressed by applying the MIST fits to ten samples of cluster galaxies. The FP slopes are actually consistent between the different samples, but, due to the large uncertainties, they could also hide significant systematic differences. The feasibility of the measurement of the possible variations of the FP slopes as a function of redshift is also proved.

Mist

10.48550/arxiv.astro-ph/0011075

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The different physical mechanisms that drive the star formation histories of giant and dwarf galaxies

Monthly Notices of the Royal Astronomical Society (2007)

C. P. Haines A. Gargiulo F. La Barbera A. Mercurio P. Merluzzi

We present an analysis of star-formation and nuclear activity in galaxies as a function of both luminosity and environment in the SDSS DR4 dataset. Using a sample of 27753 galaxies at 0.00590% complete to Mr=-18.0 we find that the EW(Ha) distribution is strongly bimodal, allowing galaxies to be robustly separated into passive and star-forming populations about a value EW(Ha)=2A. In high-density regions ~70% of galaxies are passive independent of luminosity. In the rarefied field however, the fraction of passively-evolving galaxies is a strong function of luminosity, dropping from ~50% for Mr

Dwarf spheroidal galaxy

Dwarf galaxy problem

10.1111/j.1365-2966.2007.12189.x

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Citations (126)

Young stellar population gradients in central cluster galaxies from NUV and optical spectroscopy

Monthly Notices of the Royal Astronomical Society (2020)

N Salvador-Rusiñol Michael A. Beasley A. Vazdekis F. La Barbera

Central cluster galaxies are the largest and most massive galaxies in the Universe. Although they host very old stellar populations, several studies found the existence of blue cores in some BCGs indicating ongoing star formation. We analyse VLT/X-Shooter stacked spectra of 6 nearby massive central galaxies with high central velocity dispersions ($\sigma$>300 km/s) at different galactocentric distances. We quantify the young stellar population out to 4 kpc by fitting near-UV and optical absorption line indices with predictions of composite stellar populations modelled by an old and a young stellar component. We also use IMF-sensitive indices since these galaxies have been found to host a bottom-heavy IMF in their central regions. We derive negative young stellar populations gradients, with mass fractions of stars younger than 1 Gyr decreasing with galactocentric distance, from 0.70% within 0.8 kpc to zero beyond 2 kpc. We also measure the mass fraction in young stars for individual galaxies in the highest S/N central regions. All the galaxies have young components of less than one percent. Our results clearly suggest that the star formation in massive central cluster galaxies takes place in their galaxy cores (<2 kpc), which, with deeper gravitational potential wells, are capable of retaining more gas. Among the possible sources for the gas required to form these young stars, our results are consistent with an in-situ origin via stellar evolution, which is sufficient to produce the observed young stellar populations.

Stellar population

Stellar mass

Gravitational potential

10.1093/mnras/staa3419

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Citations (15)

2DPHOT: A Multi-Purpose Environment for the Two-Dimensional Analysis of Wide-Field Images

Publications of the Astronomical Society of the Pacific (2008)

F. La Barbera R. R. de Carvalho J. L. Kohl-Moreira R. R. Gal M. Soares-Santos

We describe 2DPHOT, a general-purpose analysis environment for source detection and analysis in deep wide-field images. 2DPHOT is an automated tool to obtain both integrated and surface photometry of galaxies in an image, to perform reliable star-galaxy separation with accurate estimates of contamination at faint flux levels, and to estimate completeness of the image catalog. We describe the analysis strategy on which 2DPHOT is based, and provide a detailed description of the different algorithms implemented in the package. This new environment is intended as a dedicated tool to process the wealth of data from wide-field imaging surveys. To this end, the package is complemented by 2DGUI, an environment that allows multiple processing of data using a range of computing architectures.

Completeness (order theory)

10.1086/588614

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Citations (59)

Galaxy evolution as a function of environment and luminosity

arXiv (Cornell University) (2010)

A. Mercurio C. P. Haines A. Gargiulo F. La Barbera P. Merluzzi

We present an analysis of star formation and nuclear activity of about 28000 galaxies in a volume-limited sample taken from SDSS DR4 low-redshift catalogue (LRC) taken from the New York University Value Added Galaxy Catalogue (NYU-VAGC) of Blanton et al. 2005, with 0.005~ L*) galaxies. Moreover the fraction of galaxies with the optical signatures of an active galactic nucleus (AGN) decreases steadily from ~50\% at Mr~-21 to ~0 per cent by Mr~-18 closely mirroring the luminosity dependence of the passive galaxy fraction in low-density environments (see fig. 1 continuous lines). This result reflects the increasing importance of AGN feedback with galaxy mass for their evolution, such that the star formation histories of massive galaxies are primarily determined by their past merger history.

10.48550/arxiv.1006.5001

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Citations (2)