Poetic Castles in Spain

Saglia, Diego

doi:10.1163/9789004486737

Cited by 102 publications

(4 citation statements)

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“…Small, positive age gradients are also consistent with observations (e.g. Saglia et al 2000), and have been detected in the lowredshift population of ETGs (La Barbera & de Carvalho 2009;Clemens et al 2009). Positive color gradients in high-redshift ETGs have been observed by Ferreras et al (2005), who found that about one-third of field ETGs at z ∼ 0.7 have blue cores, in contrast to only 10% at lower redshift (see also Menanteau et al 2001Menanteau et al , 2004Ferreras et al 2009).…”

Section: Introductionsupporting

confidence: 88%

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Spider. Iv. Optical and Near-Infrared Color Gradients in Early-Type Galaxies: New Insight Into Correlations With Galaxy Properties

Barbera

Carvalho

Rosa

et al. 2010

The Astronomical Journal

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We present an analysis of stellar population gradients in 4,546 Early-Type Galaxies (ETGs) with photometry in grizYHJK along with optical spectroscopy. ETGs were selected as bulge-dominated systems, displaying passive spectra within the SDSS fibers. A new approach is described which utilizes color information to constrain age and metallicity gradients. Defining an effective color gradient, ∇ ⋆ , which incorporates all of the available color indices, we investigate how ∇ ⋆ varies with galaxy mass proxies, i.e. velocity dispersion, stellar (M ⋆ ) and dynamical (M dyn ) masses, as well as age, metallicity, and [α/Fe]. ETGs with M dyn larger than 8.5 × 10 10 M ⊙ have increasing age gradients and decreasing metallicity gradients wrt mass, metallicity, and enhancement. We find that velocity dispersion and [α/Fe] are the main drivers of these correlations. ETGs with 2.5 × 10 10 M ⊙ ≤ M dyn ≤ 8.5 × 10 10 M ⊙ , show no correlation of age, metallicity, and color gradients wrt mass, although color gradients still correlate with stellar population parameters, and these correlations are independent of each other. In both mass regimes, the striking anti-correlation between color gradient and α-enhancement is significant at ∼ 5 σ, and results from the fact that metallicity gradient decreases with [α/Fe]. This anti-correlation may reflect the fact that star formation and metallicity enrichment are regulated by the interplay between the energy input from supernovae, and the temperature and pressure of the hot X-ray gas in ETGs. For all mass ranges, positive age gradients are associated with old galaxies (> 5 − 7 Gyr). For galaxies younger than ∼ 5 Gyr, mostly at low-mass, the age gradient tends to be anti-correlated with the Age parameter, with more positive gradients at younger ages.

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Section: Introductionsupporting

confidence: 88%

“…Although the age-metallicity degeneracy makes the interpretation of the color gradient troublesome, metallicity gradient seems to be main cause (e.g. Saglia et al 2000;La Barbera et al 2003). Small, positive age gradients are also consistent with observations (e.g.…”

Section: Introductionsupporting

confidence: 77%

Spider. Iv. Optical and Near-Infrared Color Gradients in Early-Type Galaxies: New Insight Into Correlations With Galaxy Properties

Barbera

Carvalho

Rosa

et al. 2010

The Astronomical Journal

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“…It has been shown that (i) color gradients are mainly driven by a mean metallicity gradient in the range of ∇ Z = −0.2 to ∇ Z = −0.3, with an uncertainty of ∼ 0.1; and that (ii) a small positive age gradient of ∇ t ∼ 0.1 is also consistent with observations (see e.g. Peletier et al 1990;Saglia et al 2000;Idiart, Michard & de Freitas Pacheco 2002;La Barbera et al 2003a;Tamura & Ohta 2003). Here, we denote as ∇ Z and ∇ t the logarithmic variations of metallicity and age per decade in galaxy radius.…”

Section: )supporting

confidence: 72%

Sérsic Galaxy with Sérsic Halo Models of Early-type Galaxies: A Tool forN-body Simulations

Coppola¹,

Barbera²,

Capaccioli³

2009

PUBL ASTRON SOC PAC

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We present spherical, non-rotating, isotropic models of early-type galaxies with stellar and darkmatter components both described by deprojected Sersic density profiles, and prove that they represent physically admissible stable systems. Using empirical correlations and recent results of N-body simulations, all the free parameters of the models are expressed as functions of one single quantity: the total (B-band) luminosity of the stellar component.We analyze how to perform discrete N-body realizations of Sersic models. To this end, an optimal smoothing length is derived, defined as the softening parameter minimizing the error on the gravitational potential for the deprojected Sersic model. It is shown to depend on the Sersic index n and on the number of particles of the N-body realization.A software code allowing the computations of the relevant quantities of one-and two-component Sersic models is provided. Both the code and the results of the present work are primarily intended as tools to perform N-body simulations of early-type galaxies, where the structural non-homology of these systems (i.e. the variation of the shape parameter along the galaxy sequence) might be taken into account.

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“…Color gradients of distant early-types have been studied using optical HST images, and such studies have excluded models where the color gradient is driven purely by age (Tamura et al 2001;Saglia et al 2000). However, they put few constraints on the more plausible age+metallicity gradient model, due to the fact that the age effect, when buried under the metallicity gradient, is barely detectable in observed optical passbands (see section 5).…”

Section: Introductionmentioning

confidence: 99%

Optical–Near-Infrared Color Gradients in Early-Type Galaxies at [CLC][ITAL]z[/ITAL][/CLC] ≤ 1.0

Hinkley

2001

The Astrophysical Journal

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Recent studies based on line indices of nearby early-type galaxies suggest that stars in the galaxies' inner part may be younger and more metal rich than stars in the outer part. If confirmed, the finding has a profound implication for the formation and evolution of early-type galaxies, since such age gradients naturally arise if merging played an important role in their formation/evolution. As an indpendent test for the existence of the age gradient, we investigate the optical-NIR color gradients of six field early-type galaxies at z ≃0.4 -1.0 where the age gradient is expected to be detectable when combined with z = 0 calibrations. By utilizing HST NICMOS H-band imaging along with WFPC2 optical data, we obtain a broad wavelength baseline, giving results that are sensitive to the expected age gradient. When compared with simple model predictions, five of the objects show negligible age gradients and are metallicity gradient dominated, while the remaining object shows a color gradient consistent with the age+metallicity gradient picture. Our results suggest that stars within early-type galaxies may be coeval at z ∼ 1, but sprinkling of young stars might have occured at z < 1.

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Poetic Castles in Spain

Cited by 102 publications

References 0 publications

Spider. Iv. Optical and Near-Infrared Color Gradients in Early-Type Galaxies: New Insight Into Correlations With Galaxy Properties

Spider. Iv. Optical and Near-Infrared Color Gradients in Early-Type Galaxies: New Insight Into Correlations With Galaxy Properties

Sérsic Galaxy with Sérsic Halo Models of Early-type Galaxies: A Tool forN-body Simulations

Optical–Near-Infrared Color Gradients in Early-Type Galaxies at [CLC][ITAL]z[/ITAL][/CLC] ≤ 1.0

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