VLT/X-Shooter Near-Infrared Spectroscopy and HST Imaging of Gravitationally-Lensed z~2 Compact Quiescent Galaxies

Abstract

Quiescent massive galaxies at z~2 are thought to be the progenitors of present-day massive ellipticals. Observations revealed them to be extraordinarily compact. The determination of stellar ages, star formation rates and dust properties via spectroscopic measurements has up to now only been feasible for the most luminous and massive specimens (~3x M*). Here we present a spectroscopic study of two near-infrared selected galaxies which are close to the characteristic stellar mass M* (~0.9x M* and ~1.3x M*) and whose observed brightness has been boosted by the gravitational lensing effect. We measure the redshifts of the two galaxies to be z=1.71\pm0.02 and z=2.15\pm0.01. By fitting stellar population synthesis models to their spectro-photometric SEDs we determine their ages to be 2.4^{+0.8}_{-0.6} Gyr and 1.7\pm0.3 Gyr, respectively, which implies that the two galaxies have higher mass-to-light ratios than most quiescent z~2 galaxies in other studies. We find no direct evidence for active star-formation or AGN activity in either of the two galaxies, based on the non-detection of emission lines. Based on the derived redshifts and stellar ages we estimate the formation redshifts to be z=4.3^{+3.4}_{-1.2} and z=4.3^{+1.0}_{-0.6}, respectively. We use the increased spatial resolution due to the gravitational lensing to derive constraints on the morphology. Fitting Sersic profiles to the de-lensed images of the two galaxies confirms their compactness, with one of them being spheroid-like, and the other providing the first confirmation of a passive lenticular galaxy at a spectroscopically derived redshift z~2.

accepted for publication in ApJ

References in corpus (24)

• COSMOS Photometric Redshifts with 30-bands for 2-deg2
• An ultra-deep near-infrared spectrum of a compact quiescent galaxy at z=2.2
• The rapid formation a large rotating disk galaxy three billion years after the Big Bang
• Size evolution of the most massive galaxies at 1.7<z<3 from GOODS NICMOS survey imaging
• A complete sample of twelve very X-ray luminous galaxy clusters at z>0.5
• Stellar Kinematics of z~2 Galaxies and the Inside-Out Growth of Quiescent Galaxies
• The Majority of Compact Massive Galaxies at z~2 are Disk Dominated
• NICMOS Imaging of DRGs in the HDF-S: A Relation Between Star-Formation and Size at z ~ 2.5
• Superdense massive galaxies in the Nearby Universe
• The First Appearance of the Red Sequence of Galaxies in Proto-Clusters at 2<~z<~3
• Gravitationally Lensed Galaxies at 2<z<3.5: Direct Abundance Measurements of Lya Emitters
• A Near-Infrared Spectroscopic Survey of K-selected Galaxies at z~2.3: Redshifts and Implications for Broadband Photometric Studies
• The rest-frame optical luminosity functions of galaxies at 2<z<3.5
• 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
• The Low Mass End of the Fundamental Relation for Gravitationally Lensed Star Forming Galaxies at 1<z<6
• Constraining the population of 6 < z < 10 star-forming galaxies with deep near-IR images of lensing clusters
• The Nascent Red Sequence at z~2
• Morphologies of Two Massive Old Galaxies at z ~ 2.5
• Extinction Corrected Star Formation Rates Empirically Derived from Ultraviolet-Optical Colors
• Shape Evolution of Massive Early-Type Galaxies: Confirmation of Increased Disk Prevalence at z>1
• On the multiplicity of supernovae within host galaxies
• A Strongly-Lensed Massive Ultra-Compact Quiescent Galaxy at z ~ 2.4 in the COSMOS/UltraVISTA Field
• EROs found behind lensing clusters. II. Stellar populations and dust properties of optical dropout EROs and comparison with related objects
• EROs found behind lensing clusters: II.Empirical properties, classification, and SED modelling based on multi-wavelength observations

Cited by in corpus (13)

• A massive, dead disk galaxy in the early Universe
• Resolving Quiescent Galaxies at $z\gtrsim 2$: II. Direct Measures of Rotational Support
• Discovery of a Strongly Lensed Massive Quiescent Galaxy at z=2.636: Spatially Resolved Spectroscopy and Indications of Rotation
• Resolving Quiescent Galaxies at $z\gtrsim 2$: I. Search for Gravitationally Lensed Sources and Characterization of their Structure, Stellar Populations, and Line Emission
• Spectroscopic Confirmation of an Ultra Massive and Compact Galaxy at z=3.35: A Detailed Look at an Early Progenitor of Local Most Massive Ellipticals
• Stellar content of extremely red quiescent galaxies at z>2
• A spectroscopic follow-up program of very massive galaxies at 3<z<4: confirmation of spectroscopic redshifts, and a high fraction of powerful AGN
• X-shooter Spectroscopy and HST Imaging of 15 Ultra Massive Quiescent Galaxies at $z\gtrsim 2$
• An exquisitely deep view of quenching galaxies through the gravitational lens: Stellar population, morphology, and ionized gas
• Stellar Velocity Dispersion for a Strongly-Lensed, Intermediate-Mass Quiescent Galaxy at z=2.8
• REQUIEM-2D: Spatially Resolved Stellar Populations from HST 2D Grism Spectroscopy
• REQUIEM-2D: A diversity of formation pathways in a sample of spatially-resolved massive quiescent galaxies at z~2
• Discovery of two Einstein crosses from massive post--blue nugget galaxies at z>1 in KiDS