Intrinsic Colors and Ages of Extremely Red Elliptical Galaxies at High Redshift

López-Corredoira, Martín

doi:10.1088/0004-6256/139/2/540

“…Also, this assembly epoch seems to depend strongly on the galaxy mass and its environment (Thomas et al 2005;di Serego Alighieri et al 2005Pérez-González et al 2008b;Cooper et al 2010;Niemi et al 2010;Vikram et al 2010). The wide range of ages found for E-S0's (∼ 2-15 Gyr) and the disagreement between optical and NIR age estimators (sometimes, of up to ∼ 6 Gyr for a given galaxy) indicate that E-S0's have been built up at different epochs and through different mechanisms, basically depending on their masses (Trager et al 2000;Bregman et al 2006;López-Corredoira 2010). It is generally accepted that the time period at 1 < z < 2 is a transition era in which an increasing fraction of galaxies end their star formation activity and move onto the Red Sequence (Arnouts et al 2007, but see also Ellis 1997;Cristóbal-Hornillos et al 2003;Eliche-Moral et al 2006b;Taylor et al 2009;Brammer et al 2011a;Domínguez Sánchez et al 2011).…”

Section: Introductionmentioning

confidence: 99%

Evolutionary paths among different red galaxy types at 0.3 < z < 1.5 and the late buildup of massive E-S0s through major mergers

Prieto

¹

,

Eliche‐Moral

²

,

Balcells

³

et al. 2012

Monthly Notices of the Royal Astronomical Society

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Some recent observations seem to disagree with hierarchical theories of galaxy formation about the role played by major mergers in the late buildup of massive E-S0's. We re-address this question by analysing the morphology, structural distortion level, and star formation enhancement of a sample of massive galaxies (M * > 5 × 10 10 M ⊙ ) lying on the Red Sequence and its surroundings at 0.3 < z < 1.5. We have used an initial sample of ∼1800 sources with K s < 20.5 mag over an area ∼ 155 arcmin 2 on the Groth Strip, combining data from the Rainbow Extragalactic Database and the GOYA Survey. Red galaxy classes that can be directly associated to intermediate stages of major mergers and to their final products have been defined. We report observational evidence of the existence of a dominant evolutionary path among massive red galaxies at 0.6 < z < 1.5, consisting in the conversion of irregular disks into irregular spheroids, and of these ones into regular spheroids. This result implies: 1) the massive red regular galaxies at low redshifts derive from the irregular ones populating the Red Sequence and its neighbourhood at earlier epochs up to z ∼ 1.5; 2) the progenitors of the bulk of present-day massive red regular galaxies have been disks that seem to have migrated to the Red Sequence mostly through major mergers at 0.6 < z < 1.2 (these mergers thus starting at z ∼ 1.5); and 3) the formation of E-S0's that end up with M * > 10 11 M ⊙ at z = 0 through gas-rich major mergers has frozen since z ∼ 0.6. All these facts support that major mergers have played a dominant role in the definitive buildup of present-day E-S0's with M * > 10 11 M ⊙ at 0.6 < z < 1.2, in good agreement with hierarchical scenarios of galaxy formation.

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“…≤ 3.8. From these galaxies, the rest (B − V) color was determined through spectral energy distribution (SED) using templates of galaxies with the software Interrest v2.0 (Taylor et al 2009;López-Corredoira 2010). Average colors (B − V) between 0.7 and 0.8 (Vega calibration) were obtained.…”

Section: High Redshift Samplementioning

confidence: 99%

Stellar content of extremely red quiescent galaxies atz> 2

López-Corredoira

¹

,

Vazdekis

²

,

Gutiérrez

³

et al. 2017

A&A

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Context. A set of 20 extremely red galaxies at 2.5 ≤ z phot. ≤ 3.8 with photometric features of old passive-evolving galaxies without dust, with stellar masses of ∼ 10 11 M ⊙ , have colors that could be related to passive-evolving galaxies with mean ages larger than 1 Gyr. This suggests they have been formed, on average, when the Universe was very young (< 1 Gyr). Aims. We provide new estimates for the stellar content of these 20 galaxies, with a deeper analysis for two of them that includes spectroscopy. Methods. We obtained, with the GRANTECAN-10.4 m, ultraviolet rest-frame spectra of two galaxies and analyzed them together with photometric data. The remaining 18 galaxies are analyzed only with photometry. We fit the data with models of a single-burst stellar population (SSP), combinations of two SSPs, as well as with extended star formation. Results. Fits based on one SSP do not provide consistent results for the blue and red wavelengths. Moreover, the absence in the spectra of a break at ∼ 2 × 10 3 Å indicates that a rather young component is necessary. Using two SSPs we can match the photometric and spectroscopic data, with the bulk of the stellar population being very old (several Gyr) and the remaining contribution (< 5% of stellar mass fraction) from a young, likely residual star formation component with age 0.1 Gyr. Exponentially decaying extended star formation (τ) models improve slightly the fits with respect to the single burst model, but they are considerably worse than the two SSP based fits, further supporting the residual star formation scenario. Conclusions. The fact that one SSP cannot match these early-type galaxies highlights the limitations for the use of age estimators based on single lines or breaks, such as the Balmer break used in cosmic chronometers, thus questioning this approach for cosmological purposes.

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“…≤ 3.8. From these galaxies, the rest (B − V) color was determined through spectral energy distribution (SED) using templates of galaxies with the software Interrest v2.0 (Taylor et al 2009;López-Corredoira 2010). Average colors (B − V) between 0.7 and 0.8 (Vega calibration) were obtained.…”

Section: High Redshift Samplementioning

confidence: 99%

Stellar content of extremely red quiescent galaxies at z > 2 (Corrigendum)

López-Corredoira

¹

,

Vazdekis

²

,

Gutiérrez

³

et al. 2017

A&A

View full text Add to dashboard Cite

Context. A set of 20 extremely red galaxies at 2.5 ≤ z phot. ≤ 3.8 with photometric features of old passive-evolving galaxies without dust, with stellar masses of ∼ 10 11 M ⊙ , have colors that could be related to passive-evolving galaxies with mean ages larger than 1 Gyr. This suggests they have been formed, on average, when the Universe was very young (< 1 Gyr). Aims. We provide new estimates for the stellar content of these 20 galaxies, with a deeper analysis for two of them that includes spectroscopy. Methods. We obtained, with the GRANTECAN-10.4 m, ultraviolet rest-frame spectra of two galaxies and analyzed them together with photometric data. The remaining 18 galaxies are analyzed only with photometry. We fit the data with models of a single-burst stellar population (SSP), combinations of two SSPs, as well as with extended star formation. Results. Fits based on one SSP do not provide consistent results for the blue and red wavelengths. Moreover, the absence in the spectra of a break at ∼ 2 × 10 3 Å indicates that a rather young component is necessary. Using two SSPs we can match the photometric and spectroscopic data, with the bulk of the stellar population being very old (several Gyr) and the remaining contribution (< 5% of stellar mass fraction) from a young, likely residual star formation component with age 0.1 Gyr. Exponentially decaying extended star formation (τ) models improve slightly the fits with respect to the single burst model, but they are considerably worse than the two SSP based fits, further supporting the residual star formation scenario. Conclusions. The fact that one SSP cannot match these early-type galaxies highlights the limitations for the use of age estimators based on single lines or breaks, such as the Balmer break used in cosmic chronometers, thus questioning this approach for cosmological purposes.

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Intrinsic Colors and Ages of Extremely Red Elliptical Galaxies at High Redshift

Cited by 8 publications

References 39 publications

Evolutionary paths among different red galaxy types at 0.3 < z < 1.5 and the late buildup of massive E-S0s through major mergers

Evolutionary paths among different red galaxy types at 0.3 < z < 1.5 and the late buildup of massive E-S0s through major mergers

Stellar content of extremely red quiescent galaxies atz> 2

Stellar content of extremely red quiescent galaxies at z > 2 (Corrigendum)

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