Dynamical masses of early-type galaxies at z~2: Are they truly superdense?

Abstract

We measured stellar velocity dispersions sigma and dynamical masses of 9 massive (M~10^11 Msun) early-type galaxies (ETG) from the GMASS sample at redshift 1.4<z<2.0. The sigma are based on individual spectra for two galaxies at z~1.4 and on a stacked spectrum for 7 galaxies with 1.6<z<2.0, with 202-h of exposure at the ESO Very Large Telescope. We constructed detailed axisymmetric dynamical models for the objects, based on the Jeans equations, taking the observed surface brightness (from deep HST/ACS observations), PSF and slit effects into account. Our dynamical masses M_Jeans agree within ~30% with virial estimates M_vir=5*Re*sigma^2/G, although the latter tend to be smaller. This suggests that sizes are not underestimated by more than a similar fraction. Our M_Jeans also agrees within a factor <2 with the M_pop previously derived using stellar population models and 11 bands photometry. This confirms that the galaxies are intrinsically massive. The inferred mass-to-light ratios M/L_U in the very age-sensitive rest frame U-band are consistent with passive evolution in the past ~1 Gyr (formation redshift z_f~3). A 'bottom-light' stellar Initial Mass Function (IMF) appears to be required to ensure close agreement between M_Jeans and M_pop at z~2, as it does at z~0. The GMASS ETGs are on average more dense than their local counterpart. However a few percent of local ETGs of similar dynamical masses also have comparable sigma and mass surface density Sigma_50 inside Re.

6 pages, 4 figures, LaTeX with emulateapj. Accepted for publication in ApJ Letters

References in corpus (11)

• Measuring the inclination and mass-to-light ratio of axisymmetric galaxies via anisotropic Jeans models of stellar kinematics
• Size evolution of the most massive galaxies at 1.7<z<3 from GOODS NICMOS survey imaging
• The Gemini Deep Deep Survey: III. The abundance of massive galaxies 3-6 billion years after the Big Bang
• 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 Kormendy relation of massive elliptical galaxies at z~1.5. Evidence for size evolution ?
• The redshift evolution of early-type galaxies in COSMOS: Do massive early-type galaxies form by dry mergers?
• Evolution in the structural properties of early-type Brightest Cluster Galaxies at small lookback time and dependence on the environment
• Testing the Accuracy of Synthetic Stellar Libraries
• Spatially Resolved Stellar Kinematics of Field Early-Type Galaxies at z=1: Evolution of the Rotation Rate
• Dynamical Models of Elliptical Galaxies in z=0.5 Clusters: I. Data-Model Comparison and Evolution of Galaxy Rotation

Cited by in corpus (45)

• Improving the full spectrum fitting method: accurate convolution with Gauss-Hermite functions
• Dynamical modelling of the Galactic bulge and bar: the Milky Way's bar pattern speed, stellar, and dark matter mass distribution
• Unification of the Fundamental Plane and Super-Massive Black Holes Masses
• The MASSIVE Survey - I. A Volume-Limited Integral-Field Spectroscopic Study of the Most Massive Early-Type Galaxies within 108 Mpc
• Made-to-Measure models of the Galactic Box/Peanut bulge: stellar and total mass in the bulge region
• The Assembly Histories of Quiescent Galaxies Since z=0.7 from Absorption Line Spectroscopy
• The Carnegie-Irvine Galaxy Survey. III. The Three-Component Structure of Nearby Elliptical Galaxies
• The SL2S Galaxy-scale Lens Sample. II. Cosmic evolution of dark and luminous mass in early-type galaxies
• 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
• Understanding the Structural Scaling Relations of Early-Type Galaxies
• MOSFIRE Spectroscopy of Quiescent Galaxies at 1.5 < z < 2.5. I - Evolution of Structural and Dynamical Properties
• Keck-I MOSFIRE spectroscopy of compact star-forming galaxies at z$\gtrsim$2: High velocity dispersions in progenitors of compact quiescent galaxies
• Hiding in plain sight: An abundance of compact massive spheroids in the local Universe
• The SAMI Pilot Survey: The Kinematic Morphology-Density Relation in Abell 85, Abell 168 and Abell 2399
• Minor Mergers or Progenitor Bias? The Stellar Ages of Small and Large Quenched Early-Type Galaxies
• The massive relic galaxy NGC 1277 is dark matter deficient. From dynamical models of integral-field stellar kinematics out to five effective radii
• The Number Density of Quiescent Compact Galaxies at Intermediate Redshift
• The number density of superdense early-type galaxies at 1<z<2 and the local cluster galaxies
• The KMOS Cluster Survey (KCS) I: The fundamental plane and the formation ages of cluster galaxies at redshift $1.4<z<1.6$
• Dozens of compact and high velocity-dispersion early-type galaxies in Sloan Digital Sky Survey
• Redshift evolution of the dynamical properties of massive galaxies from SDSS-III/BOSS
• The kinematics of massive quiescent galaxies at $1.4<z<2.1$: dark matter fractions, IMF variation, and the relation to local early-type galaxies
• A unified model for age-velocity dispersion relations in Local Group galaxies: Disentangling ISM turbulence and latent dynamical heating
• MAGAZ3NE: High Stellar Velocity Dispersions for Ultra-Massive Quiescent Galaxies at $z\gtrsim 3$
• X-ray binary accretion states in Active Galactic Nuclei? Sensing the accretion disc of supermassive black holes with mid-infrared nebular lines
• Consistent dynamical and stellar masses with potential light IMF in massive quiescent galaxies at $3<z<4$ using velocity dispersions measurements with MOSFIRE
• The MASSIVE Survey -- XV. A Stellar Dynamical Mass Measurement of the Supermassive Black Hole in Massive Elliptical Galaxy NGC 1453
• The Rising Stellar Velocity Dispersion of M87 from Integrated Starlight
• The interstellar medium and feedback in the progenitors of the compact passive galaxies at z~2
• Spectral detection of multiple stellar populations in z~1 early-type galaxies
• The KMOS Cluster Survey (KCS) III: fundamental plane of cluster galaxies at $z\simeq 1.80$ in JKCS 041
• The evolution of disc galaxies with and without classical bulges since z~1
• Merger-driven evolution of the effective stellar initial mass function of massive early-type galaxies
• Cosmic evolution of the H2 mass density and the epoch of molecular gas
• The APOGEE Library of Infrared SSP Templates (A-LIST): High-Resolution Simple Stellar Population Spectral Models in the H-Band
• Lower mass normalization of the stellar initial mass function for dense massive early-type galaxies at z ~ 1.4
• When relics were made: vigorous stellar rotation and low dark matter content in the massive ultra-compact galaxy GS-9209 at z=4.66
• Evolution of massive quiescent galaxies via envelope accretion
• Use of spatial cross correlation function to study formation mechanism of massive elliptical galaxies
• Kinematics of molecular gas in star-forming galaxies with large-scale ionised outflows
• The validation of made-to-measure method for reconstruction of phase space distribution functions
• The GECKOS survey: Jeans anisotropic models of edge-on discs uncover the impact of dust and kinematic structures
• Quiescent Galaxy Size, Velocity Dispersion, and Dynamical Mass Evolution
• Cross-checking SMBH mass estimates in NGC 6958 -- I: Stellar dynamics from adaptive optics-assisted MUSE observations
• Kiloparsec-scale imaging of the CO(1-0)-traced cold molecular gas reservoir in a z~3.4 submillimeter galaxy