Dynamical Models of Elliptical Galaxies in z=0.5 Clusters: I. Data-Model Comparison and Evolution of Galaxy Rotation

Abstract

We present spatially resolved stellar rotation velocity and velocity dispersion profiles form Keck/LRIS absorption-line spectra for 25 galaxies, mostly visually classified ellipticals, in three clusters at z=0.5. We interpret the kinematical data and HST photometry using oblate axisymmetric two-integral f(E,Lz) dynamical models based on the Jeans equations. This yields good fits, provided that the seeing and observational characteristics are carefully modeled. The fits yield for each galaxy the dynamical M/L and a measure of the galaxy rotation rate. Paper II addresses the implied M/L evolution. Here we study the rotation-rate evolution by comparison to a sample of local elliptical galaxies of similar present-day luminosity. The brightest galaxies in the sample all rotate too slowly to account for their flattening, as is also observed at z=0. But the average rotation rate is higher at z=0.5 than locally. This may be due to a higher fraction of misclassified S0 galaxies (although this effect is insufficient to explain the observed strong evolution of the cluster S0 fraction with redshift). Alternatively, dry mergers between early-type galaxies may have decreased the average rotation rate over time. It is unclear whether such mergers are numerous enough in clusters to explain the observed trend quantitatively. Disk-disk mergers may affect the comparison through the so-called progenitor bias, but this cannot explain the direction of the observed rotation-rate evolution. Additional samples are needed to constrain possible environmental dependencies and cosmic variance in galaxy rotation rates. Either way, studies of the internal stellar dynamics of distant galaxies provide a valuable new approach for exploring galaxy evolution.

ApJ, submitted; 17 pages formatted with emulateapj

References in corpus (41)

• Maps of Dust IR Emission for Use in Estimation of Reddening and CMBR Foregrounds
• First Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Determination of Cosmological Parameters
• The Demography of Massive Dark Objects in Galaxy Centres
• Final Results from the Hubble Space Telescope Key Project to Measure the Hubble Constant
• Galaxy Harassment and the Evolution of Clusters of Galaxies
• The SAURON project - IV. The mass-to-light ratio, the virial mass estimator and the fundamental plane of elliptical and lenticular galaxies
• Evolution since z = 0.5 of the Morphology-Density relation for Clusters of Galaxies
• The SAURON project -- X. The orbital anisotropy of elliptical and lenticular galaxies: revisiting the (V/sigma,epsilon) diagram with integral-field stellar kinematics
• The Sloan Lens ACS Survey. III - The Structure and Formation of Early-type Galaxies and their Evolution since z~1
• A Spectroscopic Catalog of 10 Distant Rich Clusters of Galaxies
• A Direct Measurement of Major Galaxy Mergers at z < 3
• The SAURON project - III. Integral-field absorption-line kinematics of 48 elliptical and lenticular galaxies
• Massive Dark-matter halos and Evolution of Early-type Galaxies to z=1
• Statistical Properties of Collisionless Equal- and Unequal-Mass Merger Remnants of Disk Galaxies
• The Recent and Continuing Assembly of Field Ellipticals by Red Mergers
• Axisymmetric Dynamical Models of the Central Regions of Galaxies
• Hubble Space Telescope imaging of the CFRS and LDSS redshift surveys - IV. Influence of mergers in the evolution of faint field galaxies from z~1
• Properties of Early-Type, Dry Galaxy Mergers and the Origin of Massive Elliptical Galaxies
• Dry Mergers in GEMS: The Dynamical Evolution of Massive Early-Type Galaxies
• A JavaScript Passive Evolution Calculator
• The influence of gas on the structure of merger remnants
• The Deep2 Galaxy Redshift Survey: Evolution of Close Galaxy Pairs and Major-Merger Rates Up to z ~ 1.2
• A High Merger Fraction in the Rich Cluster MS1054-03 at z=0.83: Direct Evidence for Hierarchical Formation of Massive Galaxies
• Improved evidence for a black hole in M32 from HST/FOS spectra - II. Axisymmetric dynamical models
• Dynamically Close Galaxy Pairs and Merger Rate Evolution in the CNOC2 Redshift Survey
• The Evolution of Early-Type Galaxies in Distant Clusters II: Internal Kinematics of 55 Galaxies in the z=0.33 Cluster CL1358+62
• The build-up of the red-sequence in galaxy clusters since z~0.8
• A Catalog of Morphological Types in 10 Distant Rich Clusters of Galaxies
• Rotation and anisotropy of galaxies revisited
• Merger Rate of Equal-Mass Spherical Galaxies
• The Star Formation Epoch of the Most Massive Early-Type Galaxies
• Dynamical modelling of stars and gas in NGC2974: determination of mass-to-light ratio, inclination and orbital structure by Schwarzschild's method
• Spectroscopic Confirmation of Multiple Red Galaxy-Galaxy Mergers in MS1054-03 (z=0.83)
• A Slow Merger History of Field Galaxies Since z~1
• Evolution of the Color-Magnitude relation in High-Redshift Clusters: Early-type Galaxies in the Lynx Supercluster at z~1.26
• Star formation and figure rotation in the early-type galaxy NGC2974
• Galaxy Morphologies in the Cluster CL1358+62 at z=0.33
• Dynamical Models of Elliptical Galaxies in z=0.5 Clusters: II. Mass-to-Light Ratio Evolution without Fundamental Plane Assumptions
• The Frequency Function of Elliptical Galaxy Intrinsic Shapes
• A two-arm gaseous spiral in the inner 200 pc of the early-type galaxy NGC 2974: signature of an inner bar
• Radial Kinematics of Isolated Elliptical Galaxies

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• A constant limiting mass scale for flat early-type galaxies from z=1 to z=0: density evolves but shapes do not
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• Spatially Resolved Stellar Kinematics of Field Early-Type Galaxies at z=1: Evolution of the Rotation Rate
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• Constraining the Mass Profiles of Stellar Systems: Schwarzschild Modeling of Discrete Velocity Datasets
• Stellar Dynamical Models for 797 $z\sim 0.8$ Galaxies from LEGA-C
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