The Fundamental Plane of cluster spheroidal galaxies at z ∼ 1.3: evidence for mass-dependent evolution
Date Issued
2020
Author(s)
Abstract
We present spectroscopic observations obtained at the Large Binocular Telescope in the field of the cluster XLSSJ0223-0436 at z = 1.22. We confirm 12 spheroids cluster members and determine stellar velocity dispersion for 7 of them. We combine these data with those in the literature for clusters RXJ0848+4453 at z = 1.27 (8 galaxies) and XMMJ2235-2557 at z = 1.39 (7 galaxies) to determine the Fundamental Plane (FP) of cluster spheroids. We find that the FP at z ∼ 1.3 is offset and rotated (∼3σ) with respect to the local FP. The offset corresponds to a mean evolution Δlog(Mdyn/L) = (-0.5 ± 0.1)z. High-redshift galaxies follow a steeper mass-dependent Mdyn/L-Mdyn relation than local ones. Assuming Δ log(Mdyn/L) = Δ log(M*/L), higher mass galaxies [log(Mdyn/M⊙) ≥ 11.5] have a higher formation redshift (zf ≥ 6.5) than lower mass ones [z ≤2 for log(Mdyn/M⊙≤ 10)], with a median zf ≃ 2.5 for the whole sample. Also, galaxies with higher stellar mass density host stellar populations formed earlier than those in lower density galaxies. At fixed initial mass function, Mdyn/M* varies systematically with mass and mass density. It follows that the evolution of the stellar populations (M*/L) accounts for the observed evolution of Mdyn/L for Mdyn> 10^11 M⊙ galaxies, while accounts for ∼85 per cent of the evolution at Mdyn < 10^11 M⊙. We find no evidence in favour of structural evolution of individual galaxies, while we find evidences that spheroids later added to the population may account for the observed discrepancy between Δlog(Mdyn/L) and Δ log(M*/L) at masses <10^11
Volume
491
Issue
2
Start page
1777
Issn Identifier
0035-8711
Ads BibCode
2020MNRAS.491.1777S
Rights
open.access
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