Scaling relations of cluster elliptical galaxies at<i>z</i>~ 1.3

Saracco, P.; Casati, Anna; Gargiulo, A.; Longhetti, M.; Lonoce, I.; Tamburri, S.; Bettoni, D.; D’Onofrio, M.; Fasano, G.; Poggianti, Bianca M.; Boutsia, K.; Fumana, M.; Sani, E.

doi:10.1051/0004-6361/201423495

Cited by 25 publications

(53 citation statements)

References 81 publications

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“…The brightest and more massive cluster spheroids in this sample seem to have already arrived at their final configuration by the beginning of this period (cf., Saracco et al 2014) but fainter galaxies are likely to show significant evolution, analogous to the observations by Huertas-Company et al (2015) in the CANDELS field. However, most of our discussion as to the former must be qualitative for now, as there are too few bright galaxies in the small number of high redshift clusters that we observe to draw statistically valid conclusions.…”

Section: Discussionsupporting

confidence: 79%

Morphological evolution of cluster red sequence galaxies in the past 9 Gyr

Propris¹,

Bremer²,

Phillipps³

2016

Mon. Not. R. Astron. Soc.

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Galaxies arrive on the red sequences of clusters at high redshift (z > 1) once their star formation is quenched and evolve passively thereafter. However, we have previously found that cluster red sequence galaxies (CRSGs) undergo significant morphological evolution subsequent to the cessation of star formation, at some point in the past 9-10 Gyr. Through a detailed study of a large sample of cluster red sequence galaxies spanning 0.2 < z < 1.4 we elucidate the details of this evolution. Below z ∼ 0.5 − 0.6 (in the last 5-6 Gyr) there is little or no morphological evolution in the population as a whole, unlike in the previous 4-5 Gyrs. Over this earlier time (i) disklike systems with Sérsic n < 2 progressively disappear, as (ii) the range of their axial ratios similarly decreases, removing the most elongated systems (those consistent with thin disks seen at an appreciable inclination angle), and (iii) radial colour gradients (bluer outwards) decrease in an absolute sense from significant age-related gradients to a residual level consistent with the metallicity-induced gradients seen in low redshift cluster members. The distribution of their effective radii shows some evidence of evolution, consistent with growth of at most a factor < 1.5 between z ∼ 1.4 and z ∼ 0.5, significantly less than for comparable field galaxies, while the distribution of their central (< 1kpc) bulge surface densities shows no evolution at least at z < 1. A simple model involving the fading and thickening of a disk component after comparatively recent quenching (after z ∼ 1.5) around an otherwise passively evolving older spheroid component is consistent with all of these findings.

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Section: Discussionsupporting

confidence: 79%

Morphological evolution of cluster red sequence galaxies in the past 9 Gyr

Propris¹,

Bremer²,

Phillipps³

2016

Mon. Not. R. Astron. Soc.

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“…(e.g. Saracco et al 2014;Trujillo et al 2014;Ferré-Mateu et al 2012;van der Wel et al 2012;Buitrago et al 2013). In this context, very interestingly, the mean value of the β parameter we have derived for our dense high-z ETGs is 7.0±1.7, and perfectly agrees with the mean value of massive ATLAS 3D dense ETGs, 7.5 ± 1.7.…”

Section: D-dynamical Models (K) Assupporting

confidence: 85%

Lower mass normalization of the stellar initial mass function for dense massive early-type galaxies atz~ 1.4

Gargiulo

Saracco

Longhetti

et al. 2015

A&A

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Aims. This paper aims at understanding whether the normalization of the stellar initial mass function (IMF) of massive galaxies varies with cosmic time and/or with mean stellar mass density Σ = M /(2πR 2 e ). Methods. We have tackled this question by taking advantage of a spectroscopic sample of 18 dense (Σ > 2500 M pc −2 ) massive early-type galaxies (ETGs) that we collected at 1.2 < ∼ z < ∼ 1.6. Each galaxy in the sample was selected in order to have available: i) a high-resolution deep HST-F160W image to visually classify it as an ETG; ii) an accurate velocity dispersion estimate; iii) stellar mass derived through the fit of multiband photometry; and iv) structural parameters (i.e. effective radius R e and Sersic index n) derived in the F160W-band. We have constrained the mass-normalization of the IMF of dense high-z ETGs by comparing the true stellar masses of the ETGs in the sample (M true ) derived through virial theorem, hence IMF independent, with those inferred through the fit of the photometry which assume a reference IMF (M ref ). Adopting the virial estimator as proxy of the true stellar mass, we have implicitly assumed that these systems have zero dark matter. However, recent dynamical analysis of massive local ETGs have shown that the dark matter fraction within R e in dense ETGs is negligible (<5−10%) and simulations of dissipationless mergers of spheroidal galaxies have shown that this fraction decreases going back with time. Accurate dynamical models of local ETGs performed by the ATLAS 3D team have shown that the virial estimator is prone to underestimating or overestimating the total masses. We have considered this, and based on the results of ATLAS 3D we have shown that for dense ETGs the mean value of total masses derived through the virial estimator with a non-homologous virial coefficient and Sersic-R e are perfectly in agreement with the mean value of those derived through more sophisticated dynamical models, although, of course, the estimates show higher uncertainties. Results. Tracing the variation of the parameter Γ = M true /M ref with velocity dispersion σ e , we have found that, on average, dense ETGs at z = 1.4 follow the same IMF-σ e trend of typical local ETGs, but with a lower mass-normalization. The observed lower normalization could be evidence of i) an evolution of the IMF with time or ii) a correlation with Σ. To discriminate between the two possibilities, we have compared the IMF-σ e trend that we have found for high-z dense ETGs with that of local ETGs with similar mean stellar mass density and velocity dispersion and we have found that the IMF of massive dense ETGs does not depend on redshift. The similarity between the IMF-σ e trends observed both in dense high-z and low-z ETGs over 9 Gyr of evolution and their lower massnormalization with respect to the mean value of local ETGs suggests that, independently of formation redshift, the physical conditions which characterized the formation of a dense spheroid on average lead to a mass spectrum of newly formed stars ...

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“…Once considered the morphological and size caveats discussed in the previous sections, our results are consistent with the literature results, but constraining more tightly the size evolution, or differ for understood reasons detailed below. For example, Saracco et al (2014) find consistent mass-size relation comparing Coma and a z = 1.26 cluster, similarly to the more constraining work of Andreon et al (2014) that has an enlarged redshift baseline. Both works lack sensitivity, being based on a handful of galaxies at high redshift, and indeed the more stringent upper limit derived in Andreon et al (2015) is fully consistent with the change we measure in the present work.…”

Section: Appendix C: Morphological Classificationsupporting

confidence: 62%

Size growth of red-sequence early-type galaxies in clusters in the last 10 Gyr

Andreon

Dong

Raichoor

2016

A&A

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We carried out a photometric and structural analysis in the rest-frame V band of a mass-selected (log M/M > 10.7) sample of red-sequence galaxies in 14 galaxy clusters, 6 of which are at z > 1.45, namely JKCS041, IDCS J1426.5+3508, SpARCS104922.6+564032.5, SpARCSJ021524-034331, XDCPJ0044.0-2033, and SPT-CLJ2040-4451. To this end, we reduced/analyzed about 300 orbits of multicolor images taken with the Advanced Camera for Survey and the Wide Field Camera 3 on the Hubble Space Telescope. We uniformly morphologically classified galaxies from z = 0.023 to z = 1.803, and we homogeneously derived sizes (effective radii) for the entire sample. Furthermore, our size derivation allows, and therefore is not biased by, the presence of the usual variety of morphological structures seen in early-type galaxies, such as bulges, bars, disks, isophote twists, and ellipiticy gradients. By using such a mass-selected sample, composed of 244 red-sequence early-type galaxies, we find that the log of the galaxy size at a fixed stellar mass, log M/M = 11, has increased with time at a rate of 0.023 ± 0.002 dex per Gyr over the last 10 Gyr, in marked contrast with the threefold increase found in the literature for galaxies in the general field over the same period. This suggests, at face value, that secular processes should be excluded as the primary drivers of size evolution because we observed an environmental dependent size growth. Using spectroscopic ages of Coma early-type galaxies we also find that recently quenched early-type galaxies are a numerically minor population not different enough in size to alter the mean size at a given mass, which implies that the progenitor bias is minor, i.e., that the size evolution measured by selecting galaxies at the redshift of observation is indistinguishable from the one that compares ancestors and descendents.

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Scaling relations of cluster elliptical galaxies atz~ 1.3

Cited by 25 publications

References 81 publications

Morphological evolution of cluster red sequence galaxies in the past 9 Gyr

Morphological evolution of cluster red sequence galaxies in the past 9 Gyr

Lower mass normalization of the stellar initial mass function for dense massive early-type galaxies atz~ 1.4

Size growth of red-sequence early-type galaxies in clusters in the last 10 Gyr

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