SPIDER - VII. Revealing the stellar population content of massive early-type galaxies out to 8<i>R</i><sub>e</sub>

Barbera, F. La; Ferreras, Ignacio; Carvalho, R. R. de; Bruzual, G.; Charlot, S.; Pasquali, A.; Merlin, E.

doi:10.1111/j.1365-2966.2012.21848.x

Cited by 104 publications

(127 citation statements)

References 105 publications

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“…A.1). This is the normal behavior for early-type galaxies (e.g., La Barbera et al 2012) and is compatible with the negligible age and metalicity gradients found by Reda et al (2007) inside 0.5R e . No dusty features are visible.…”

Section: Galaxy Surface Brightness and Colorssupporting

confidence: 59%

Isolated ellipticals and their globular cluster systems

Salinas

Alabi

Richtler

2015

A&A

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As tracers of star formation, galaxy assembly, and mass distribution, globular clusters have provided important clues to our understanding of early-type galaxies. But their study has been mostly constrained to galaxy groups and clusters where early-type galaxies dominate, leaving the properties of the globular cluster systems (GCSs) of isolated ellipticals as a mostly uncharted territory. We present Gemini-South/GMOS g i observations of five isolated elliptical galaxies: NGC 3962, NGC 2865, IC 4889, NGC 2271, and NGC 4240. Photometry of their GCSs reveals clear color bimodality in three of them, but remains inconclusive for the other two. All the studied GCSs are rather poor with a mean specific frequency S N ∼ 1.5, independently of the parent galaxy luminosity. Considering information from previous work as well, it is clear that bimodality and especially the presence of a significant, even dominant, population of blue clusters occurs at even the most isolated systems, which casts doubts on a possible accreted origin of metal-poor clusters, as suggested by some models. Additionally, we discuss the possible existence of ultra-compact dwarfs around the isolated elliptical NGC 3962.

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Section: Galaxy Surface Brightness and Colorssupporting

confidence: 59%

Isolated ellipticals and their globular cluster systems

Salinas

Alabi

Richtler

2015

A&A

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“…Negative metallicity gradients extending to the outer radii are found in most earlytype galaxies (e.g. Baes et al 2007;La Barbera et al 2012). Flat and positive [α/Fe] gradients are commonly found in early-type galaxies at small radii (Kuntschner et al 2010), and there is evidence that, at least, metallicity gradients extend to larger radii (La Barbera et al 2012;Pastorello et al 2014).…”

Section: The Extended Symmetric Halomentioning

confidence: 99%

The Hydra I cluster core

Barbosa

Arnaboldi

Coccato

et al. 2016

A&A

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Context. The history of the mass assembly of brightest cluster galaxies may be studied by mapping the stellar populations at large radial distances from the galaxy centre, where the dynamical times are long and preserve the chemodynamical signatures of the accretion events. Aims. We provide extended and robust measurements of the stellar population parameters in NGC 3311, the cD galaxy at the centre of the Hydra I cluster, and out to three effective radii. We wish to characterize the processes that drove the build-up of the stellar light at all these radii. Methods. We obtained the spectra from several regions in NGC 3311 covering an area of ∼3 arcmin 2 in the wavelength range 4800 λ(Å) 5800, using the FORS2 spectrograph at the Very Large Telescope in the Mask exchange unit (MXU) mode. We measured the equivalent widths of seven absorption-features defined in the Lick/IDS system, which were modelled by single stellar populations, to provide luminosity-weighted ages, metallicities, and alpha element abundances. Results. The trends in the Lick indices and the distribution of the stellar population parameters indicate that the stars of NGC 3311 may be divided in two radial regimes, one within and the another beyond one effective radius, R e = 8.4 kpc, similar to the distinction between the inner galaxy and the external halo derived from the NGC 3311 velocity dispersion profile. The inner galaxy (R ≤ R e ) is old (age ∼14 Gyr), has negative metallicity gradients and positive alpha element gradients. The external halo is also very old, but has a negative age gradient. The metal and element abundances of the external halo both have a large scatter, indicating that stars from a variety of satellites with different masses have been accreted. The region in the extended halo associated with the off-centred envelope at 0• < PA < 90• has higher metallicity with respect to the symmetric external halo. Conclusions. The different stellar populations in the inner galaxy and extended halo reflect the dominance of in situ stars in the former and the accreted origin for the large majority of the stars in the latter. The low value of the velocity dispersion in the inner galaxy indicates that its stars are bound to the galaxy's gravitational potential, and the abundances and gradients suggest that the inner galaxy is formed in an outside-in scenario of merging gas-rich lumps, reminiscent of the first phase of galaxy formation. The external halo has a higher velocity dispersion, it is dynamically hotter than the galaxy and its stars are gravitationally driven by the cluster's gravitational potential. The stars in the external halo were removed from their parent galaxies, either disks with truncated star formation, or the outer regions of early-type galaxies. Late mass accretion at large radii is now coming from the tidal stripping of stars from dwarfs and S0 galaxies. These results provide supporting evidence for the recent theoretical models of formation of massive ellipticals as a two-phase process.

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“…These results are in contrast with recent results by Greene et al (2012Greene et al ( , 2013: for a sample of ∼30 early type galaxies they find at 2 R eff an old (10 Gyr) stellar population with [Fe/H] ∼ −0.5, and interpret this as the stellar outskirts of these galaxies being built up through minor mergers. Coccato et al (2010), La Barbera et al (2012), Montes et al (2014) observing a few massive ellipticals reported a decline of the metallicity to under solar in an old stellar population in their outskirts (≥10 R eff ) suggesting that these galaxies are formed in two phases, the central core through major mergers, and through minor mergers farther out. However, other recent works show examples of ETG with an old and metal-rich stellar population and a very shallow metallicity gradient up to 3 R eff in contrast with the results by Greene et al (2012Greene et al ( , 2013.…”

Section: Implications From This Work and Comparisonmentioning

confidence: 99%

The CALIFA survey across the Hubble sequence

Delgado

García-Benito

Pérez

et al. 2015

A&A

238

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Various different physical processes contribute to the star formation and stellar mass assembly histories of galaxies. One important approach to understanding the significance of these different processes on galaxy evolution is the study of the stellar population content of today's galaxies in a spatially resolved manner. The aim of this paper is to characterize in detail the radial structure of stellar population properties of galaxies in the nearby universe, based on a uniquely large galaxy sample, considering the quality and coverage of the data. The sample under study was drawn from the CALIFA survey and contains 300 galaxies observed with integral field spectroscopy. These cover a wide range of Hubble types, from spheroids to spiral galaxies, while stellar masses range from M ∼ 10 9 to 7 × 10 11 M . We apply the fossil record method based on spectral synthesis techniques to recover the following physical properties for each spatial resolution element in our target galaxies: the stellar mass surface density (µ ), stellar extinction (A V ), light-weighted and mass-weighted ages ( log age L , log age M ), and mass-weighted metallicity ( log Z M ). To study mean trends with overall galaxy properties, the individual radial profiles are stacked in seven bins of galaxy morphology (E, S0, Sa, Sb, Sbc, Sc, and Sd). We confirm that more massive galaxies are more compact, older, more metal rich, and less reddened by dust. Additionally, we find that these trends are preserved spatially with the radial distance to the nucleus. Deviations from these relations appear correlated with Hubble type: earlier types are more compact, older, and more metal rich for a given M , which is evidence that quenching is related to morphology, but not driven by mass. Negative gradients of log age L are consistent with an inside-out growth of galaxies, with the largest log age L gradients in Sb-Sbc galaxies. Further, the mean stellar ages of disks and bulges are correlated and with disks covering a wider range of ages, and late-type spirals hosting younger disks. However, age gradients are only mildly negative or flat beyond R ∼ 2 HLR (half light radius), indicating that star formation is more uniformly distributed or that stellar migration is important at these distances. The gradients in stellar mass surface density depend mostly on stellar mass, in the sense that more massive galaxies are more centrally concentrated. Whatever sets the concentration indices of galaxies obviously depends less on quenching/morphology than on the depth of the potential well. There is a secondary correlation in the sense that at the same M early-type galaxies have steeper gradients. The µ gradients outside 1 HLR show no dependence on Hubble type. We find mildly negative log Z M gradients, which are shallower than predicted from models of galaxy evolution in isolation. In general, metallicity gradients depend on stellar mass, and less on morphology, hinting that metallicity is affected by both -the depth of the potential well and morphology/quenching....

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

Cited by 104 publications

References 105 publications

Isolated ellipticals and their globular cluster systems

Isolated ellipticals and their globular cluster systems

The Hydra I cluster core

The CALIFA survey across the Hubble sequence

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

Cited by 104 publications

References 105 publications

Isolated ellipticals and their globular cluster systems

Isolated ellipticals and their globular cluster systems

The Hydra I cluster core

The CALIFA survey across the Hubble sequence

Contact Info

Product

Resources

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