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

Hinkley, Sasha; Im, Myungshin

doi:10.1086/323940

Cited by 22 publications

(32 citation statements)

References 28 publications

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“…They found that galaxies show moderate colour gradients also at intermediate redshifts, and claimed, therefore, that metallicity is the primary factor driving the observed gradients. The same conclusion was drawn by and by Hinkley & Im (2001) for early-type galaxies in the field. On the other hand, there are also some indications that the population of spheroids at intermediate redshifts is not homogeneous with respect to the radial properties of the stellar populations.…”

Section: Introductionsupporting

confidence: 83%

Evolution of UV–NIR structural properties of cluster galaxies

Barbera

Busarello

Massarotti

et al. 2003

A&A

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Abstract. We study the structure and the internal colour gradients of cluster galaxies from UV to NIR restframe, in the redshift range z = 0.21−0.64. Structural parameters (half light radius r e , mean surface brightness <µ> e and Sersic index n) are derived for galaxies in the clusters A 209 at z = 0.21 and EIS 0048 at z = 0.64. This data set, together with previous data for the cluster AC 118 at z = 0.31, constitutes the first large (N ∼ 270) sample of cluster galaxies whose internal structure in UV, optical (OPT) and NIR (U-, V-and H-band restframe) can be investigated up to a look-back time of ∼6 Gyr (Ω m = 0.3, Ω Λ = 0.7 and H 0 = 70 km s −1 Mpc −1 ). Galaxies are classified as spheroids or disks according to the shape of the light profile, and the evolution of the two populations are investigated separately. On average, both spheroids and disks are more concentrated at longer wavelengths: the galaxy sizes become smaller from UV to NIR, while Sersic indices increase. This trend shows an evolution in disks, where the mean ratio of optical to NIR Sersic indices decreases from z = 0.31 to z = 0.64. Colour gradients are on average negative at all redshifts and are stronger in disks than in spheroids. But while for spheroids both grad (UV−OPT) and grad (OPT−NIR) are only weakly dependent on redshift, the optical-NIR gradients of disks become significantly smaller at z = 0.64. Colour gradients and central colours are compared with models of metallicity, age, and dust extinction gradients. Metallicity turns out to be the primary driver of colour gradients in spheroids, the age gradient being constrained to be smaller than ∼25%. For disks, two kinds of models fit the present data: (i) age gradients (in the range [30, 50]%) with significant dust extinction, and (ii) "pure" dust models, in which the gradients of colour excess are a factor of two higher in EIS 0048 than in the other clusters. Since colour gradients of disks seem not to correlate significantly with inclination, we argue that age gradient models could represent a more likely explanation of the present data, in agreement with what expected on the basis of hierarchical merging scenarios.

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Section: Introductionsupporting

confidence: 83%

Evolution of UV–NIR structural properties of cluster galaxies

Barbera

Busarello

Massarotti

et al. 2003

A&A

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“…Some examples are: the slope of colour versus normalized radius or its logarithm (e.g. Hinkley & Im 2001; Michard 2005; Tortora et al 2010), the difference between colours outside and inside certain radius (e.g. Menanteau et al 2005; Park & Choi 2005), the comparison between model and fibre colours when working with galaxies from the SDSS (e.g.…”

Section: The Datamentioning

confidence: 99%

“…Due to the multiple phases that compose this medium the enrichment does not necessary happen in a symmetrical way, which can produce strong metallicity gradients and thus colour gradients. Galaxies with a significant age gradient can present very shallow or even inverted colour gradients (Hinkley & Im 2001), since age gradients usually arise from localized regions of star formation, generally resulting in galaxies with bluer cores than their external parts. The presence of a diffuse component of dust could also explain some colour gradients.…”

Section: Introductionmentioning

confidence: 99%

Colour gradients within SDSS DR7 galaxies: hints of recent evolution

González-Pérez

Castander

Kauffmann

2010

Monthly Notices of the Royal Astronomical Society

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The evolutionary path followed by a galaxy shapes its internal structure, and, in particular, its internal colour variation. We present a study of the internal colour variation within galaxies from the Seventh Data Release of the Sloan Digital Sky Survey (SDSS DR7). We statistically study the connection between the internal colour variation and global galactic properties, looking for hints of the recent galactic evolution. Considering only galaxies with good photometry and spectral measurements, we define four luminosity-threshold samples within the redshift range 0.01

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“…This interpretation is supported by the observations of metallicity gradients (and the lack of age gradients) in early-type galaxies (e.g Hinkley & Im, 2001;Mehlert et al, 2003;Tamura k, Ohta, 2003;Wu et al, 2004). The colour diff'erences we observe inside and outside the fibre are 5{u -5) ~ 0.15, consistent with the average (u-g) colour gradient of 0.18 found in 36 early type SDSS galaxies analysed by Wu et al (2004).…”

Section: Aperture Effects and The Origin Of Colour Gradients In Galaxmentioning

confidence: 60%

“…The main assumption present in this technique is that-thedistribution of SFR/L for a given colour is similar inside and outside the fibre. However, we know that colour gradients can also be driven by metallicity (Hinkley & Im, 2001;…”

Section: Gradients In Galaxiesmentioning

confidence: 99%

Galaxy Evolution in Groups and Clusters

Lobo¹,

Roos²,

Biviano³

2003

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The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source• a link is made to the metadata record in Durham E-Theses• the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders. AbstractIn this thesis, we investigate the extent to which galaxy evolution is driven by processes common to the group and cluster environments. A bimodality of galaxy properties such as star formation, strongly dependent upon the local overdensity of galaxies, suggests that the passive, early type galaxies common to groups and clusters originate in transformation processes, which are nurtured by the environment. This can only be important to global galaxy evolution if transformations are common in groups, which contain ^ 50% of the local galaxy population.We present deep Magellan spectroscopy and HST ACS imaging of our group and field samples at 0.3 < ^ < 0.55, selected from the CN0C2 survey by Carlberg et al. (2001b).We find that these groups contain significantly more passive galaxies than the field, with excesses of SO, elliptical and passive spiral galaxy types. The morphological composition is closely matched to that of irregular and X-ray-faint clusters at a similar epoch. In contrast with a low-redshift group sample selected from 2dFGRS (Eke et al., 2004), we find that the fraction of passive galaxies, fp, is strongly evolving in the group environment, with parallel evolution in the field population. Simple models confirm that galaxy transformations are required to match the evolution of both group and field populations. Qualitatively similar evolution and dependence on environment is found in physically-motivated simulations.However, these do not quantitatively match the environmental nor luminosity dependence in the evolution of fp. We also present a complementary method using photometric redshifts to identify infalling groups in the outskirts of clusters with Wide Field Imaging (WFI) technology.Finally,, we identify the key developments which will help to unravel the history of galaxy evolution in coming years.

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

Cited by 22 publications

References 28 publications

Evolution of UV–NIR structural properties of cluster galaxies

Evolution of UV–NIR structural properties of cluster galaxies

Colour gradients within SDSS DR7 galaxies: hints of recent evolution

Galaxy Evolution in Groups and Clusters

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