Cluster and field elliptical galaxies at z~1.3. The marginal role of the environment and the relevance of the galaxy central regions

P. Saracco; A. Gargiulo; F. Ciocca; D. Marchesini

doi:10.1051/0004-6361/201628866

paper

Cluster and field elliptical galaxies at z~1.3. The marginal role of the environment and the relevance of the galaxy central regions

arXiv:1609.06726 · doi:10.1051/0004-6361/201628866

Abstract

We compared the properties of 56 elliptical galaxies selected from three clusters at $1.2 < z < 1.4$ with those of field galaxies in the GOODS-S (~30), COSMOS (~180) and CANDELS (~220) fields. We studied the relationships among effective radius, surface brightness, stellar mass, stellar mass density $Σ_{R e}$ and central mass density $Σ_{1 k p c}$ within 1 kpc radius. We find that cluster ellipticals do not differ from field ellipticals: they share the same structural parameters at fixed mass and the same scaling relations. On the other hand, the population of field ellipticals at $z \sim 1.3$ shows a significant lack of massive ( $M_{*} > 2 \times 1 0^{11}$ M $_{⊙}$ ) and large (R $_{e} > 4 - 5$ kpc) ellipticals with respect to the cluster. Nonetheless, at $M * < 2 \times 1 0^{11}$ M $_{⊙}$ , the two populations are similar. The size-mass relation of ellipticals at z~1.3 defines two different regimes, above and below a transition mass $m_{t} \sim 2 - 3 \times 1 0^{10}$ M $_{⊙}$ : at lower masses the relation is nearly flat (R $_{e} \propto M_{*}^{- 0.1 \pm 0.2}$ ), the mean radius is constant at ~1 kpc and $Σ_{R e} \sim Σ_{1 k p c}$ while, at larger masses, the relation is R $_{e} \propto M *^{0.64 \pm 0.09}$ . The transition mass marks the mass at which galaxies reach the maximum $Σ_{R e}$ . Also the $Σ_{1 k p c}$ -mass relation follows two different regimes, $Σ_{1 k p c} \propto M *_{1.07 < m_{t}}^{0.64 > m_{t}}$ , defining a transition mass density $Σ_{1 k p c} \sim 2 - 3 \times 1 0^{3}$ M $_{⊙}$ pc $^{- 2}$ . The mass density $Σ_{R e}$ does not correlate with mass, dense/compact galaxies can be assembled over a wide mass regime, independently of the environment. The central mass density, $Σ_{1 k p c}$ , besides to be correlated with the mass, is correlated to the age of the stellar population: the higher the central stellar mass density, the higher the mass, the older the age of the stellar population. [Abridged]

arXiv commentAccepted for publication in A&A; 20 pages, 13 figures (replaced to match the A&A version)

Cluster and field elliptical galaxies at z~1.3. The marginal role of the environment and the relevance of the galaxy central regions

Abstract

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