Stellar population properties of individual massive early-type galaxies at 1.4 < z < 2

Abstract

We analyse publicly available, individual spectra of four, massive ($M>10^{11}{M}_{\odot }$) early-type galaxies with redshifts in the range 1.4 < z < 2 to determine their stellar content, extending our previous work up to z~2. The wide wavelength range of the VLT/X-Shooter spectroscopic data in the UV-Optical-NIR arms along with the availability of spectro-photometry allows us to explore different techniques to obtain the stellar population properties, namely through age/metallicity sensitive spectral indices, full spectral fitting and broad-band photometric fitting. Moreover, together with the widely used optical Lick indices we consider further indices in the UV rest-frame, and demonstrate that UV indices significantly help the accuracy of the resulting population parameters. We find galaxy ages ranging from 0.2 to 4 Gyr, where the oldest galaxy is found at the lowest redshift, with an excellent agreement between ages determined via indices, full spectral fitting or broad-band colours. These ages are in perfect agreement with ages of local galaxies at the same velocity dispersion when we assume pure passive evolution. Total metallicities derived from indices show some scatter (between less than half-solar to very high values, ([Z/H]~0.6]). We speculate on possible mechanisms explaining these values, but given the sample size and low S/N of the spectra no conclusion can be made. Indices in the UV-rest frame generally lead to similar conclusions as optical indices. For the oldest galaxy (4 Gyr) we show that its UV-indices can only be explained by stellar population models including a UV contribution from old stellar populations, suggesting that old, UV bright populations start to inhabit mature galaxies of a few Gyr of age. This is the highest redshift (z~1.4) detection of the UV-upturn up to date.

23 pages, Accepted for publication in MNRAS

References in corpus (29)

• Cosmic Star Formation History
• The UKIRT Infrared Deep Sky Survey (UKIDSS)
• An ultra-deep near-infrared spectrum of a compact quiescent galaxy at z=2.2
• Detection of quiescent galaxies in a bicolor sequence from z=0-2
• Evidence for TP-AGB stars in high redshift galaxies, and their effect on deriving stellar population parameters
• Ages and metallicities of early-type galaxies in the SDSS: new insight into the physical origin of the colour-magnitude and the Mg2-sigmaV relations
• Firefly (Fitting IteRativEly For Likelihood analYsis): a full spectral fitting code
• Superdense massive galaxies in the Nearby Universe
• Charting the evolution of the ages and metallicities of massive galaxies since z=0.7
• The metallicity of the most distant quasars
• The Carnegie-Irvine Galaxy Survey. III. The Three-Component Structure of Nearby Elliptical Galaxies
• ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Molecular gas reservoirs in high-redshift galaxies
• A massive, quiescent, population II galaxy at a redshift of 2.1
• The star formation history of early-type galaxies as a function of mass and environment
• The stellar velocity dispersion of a compact massive galaxy at z=1.80 using X-Shooter: confirmation of the evolution in the mass-size and mass-dispersion relations
• Timing the formation and assembly of early-type galaxies via spatially resolved stellar populations analysis
• SDSS-IV MaNGA: stellar population gradients as a function of galaxy environment
• The initial mass function of a massive relic galaxy
• Stellar populations and evolution of early-type cluster galaxies: Constraints from optical imaging and spectroscopy of z=0.5-0.9 galaxy clusters
• Probing recent star formation with absorption-line strengths in hierarchical models and observations
• Extremely Low Molecular Gas Content in a Compact, Quiescent Galaxy at z=1.522
• First results from the VIRIAL survey: the stellar content of $UVJ$-selected quiescent galaxies at $1.5<z<2$ from KMOS
• The early-type galaxies NGC 1407 and NGC 1400 - II: star formation and chemical evolutionary history
• The Star Formation Histories of Red-Sequence Galaxies, Mass-to-Light Ratios and the Fundamental Plane
• Passive galaxies in the early Universe: ALMA confirmation of z~3-5 candidates in the CANDELS GOODS-South field
• Absorption line indices in the UV. Empirical and theoretical stellar population models
• RXJ0848.6+4453: The Evolution of Galaxy Sizes and Stellar Populations in a z=1.27 Cluster
• Spectral detection of multiple stellar populations in z~1 early-type galaxies
• UV Upturn in Elliptical Galaxies: Theory

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• A new measurement of the expansion history of the Universe at z=1.26 with cosmic chronometers in VANDELS
• Toward a Better Understanding of Cosmic Chronometers: Stellar Population Properties of Passive Galaxies at Intermediate Redshift
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• The stellar metallicities of massive quiescent galaxies at 1.0 < z < 1.3 from KMOS+VANDELS
• Reconstructing the Assembly of Massive Galaxies. I: The Importance of the Progenitor Effect in the Observed Properties of Quiescent Galaxies at $z\approx 2$
• CLEAR: Survey Overview, Data Analysis and Products
• The star formation history and the nature of the mass-metallicity relation of passive galaxies at 1.0<z<1.4 from VANDELS
• A new perspective on the stellar Mass-Metallicity Relation of quiescent galaxies from the LEGA-C survey
• Evolution of the Ultraviolet Upturn at $0.3<z<1$: exploring helium rich stellar populations
• Stellar metallicity from optical and UV spectral indices: Test case for WEAVE-StePS
• Stellar populations of a sample of far-IR AGN and non-AGN green valley galaxies
• The Ultraviolet Upturn in field Luminous Red Galaxies at $0.3<z<0.7$
• Globular clusters as cosmic clocks: new cosmological hints from their integrated light
• The Stellar Chemical Abundances of Simulated Massive Galaxies at $z=2$
• Two categories of UV-upturn galaxies revealed by semi-analytic models
• Size-Mass Relation Shows Its Colours: Contrasting Physical Imprints of Galaxy Evolution in Rest-Frame UV and Optical
• UV bright red-sequence galaxies: a comparative study between UV upturn and UV weak systems