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Spatially resolved stellar kinematics of field early-type galaxies at z=1 : evolution of the rotation rate

(2008) ASTROPHYSICAL JOURNAL. 684(1). p.260-269
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Abstract
We use the spatial information of our previously published VLT/FORS2 absorption-line spectroscopy to measure mean stellar velocity and velocity dispersion profiles of 25 field early-type galaxies at a median redshift z = 0.97 (full range 0.6 < z < 1.2). This provides the first detailed study of early-type galaxy rotation at these redshifts. From surface brightness profiles from HST imaging we calculate two-integral oblate axisymmetric Jeans equation models for the observed kinematics. Fits to the data yield for each galaxy the degree of rotational support and the mass-to-light ratio M/L-Jeans. S0 and Sa galaxies are generally rotationally supported, whereas elliptical galaxies rotate less rapidly or not at all. Down to M-B - -19.5 (corrected for luminosity evolution), we find no evidence for evolution in the fraction of rotating early-type (E+S0) galaxies between z similar to 1 (63% +/- 11%) and the present (61% +/- 5%). We interpret this as evidence for little or no change in the field S0 fraction with redshift. We compare M/L-Jeans with M/L-vir inferred from the virial theorem and globally averaged quantities and assuming homologous evolution. There is good agreement for nonrotating (mostly E) galaxies. However, for rotationally supported galaxies (mostly S0) M/L-Jeans is on average similar to 40% higher than M/L-vir. We discuss possible explanations and the implications for the evolution of M/L between z = 1 and the present and its dependence on mass.
Keywords
MORPHOLOGY-DENSITY RELATION, TO-LIGHT RATIO, ELLIPTIC GALAXIES, FUNDAMENTAL PLANE, STAR-FORMATION, LENTICULAR GALAXIES, SAURON PROJECT, MASS-DISTRIBUTION, DYNAMICAL MODELS, Z=0.5 CLUSTERS, galaxies : elliptical and lenticular, cD, galaxies : evolution, galaxies : fundamental parameters, galaxies : kinematics and dynamics

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Chicago
van der Wel, Arjen, and Roeland P Van Der Marel. 2008. “Spatially Resolved Stellar Kinematics of Field Early-type Galaxies at Z=1 : Evolution of the Rotation Rate.” Astrophysical Journal 684 (1): 260–269.
APA
van der Wel, A., & Van Der Marel, R. P. (2008). Spatially resolved stellar kinematics of field early-type galaxies at z=1 : evolution of the rotation rate. ASTROPHYSICAL JOURNAL, 684(1), 260–269.
Vancouver
1.
van der Wel A, Van Der Marel RP. Spatially resolved stellar kinematics of field early-type galaxies at z=1 : evolution of the rotation rate. ASTROPHYSICAL JOURNAL. 2008;684(1):260–9.
MLA
van der Wel, Arjen, and Roeland P Van Der Marel. “Spatially Resolved Stellar Kinematics of Field Early-type Galaxies at Z=1 : Evolution of the Rotation Rate.” ASTROPHYSICAL JOURNAL 684.1 (2008): 260–269. Print.
@article{8575457,
  abstract     = {We use the spatial information of our previously published VLT/FORS2 absorption-line spectroscopy to measure mean stellar velocity and velocity dispersion profiles of 25 field early-type galaxies at a median redshift z = 0.97 (full range 0.6 < z < 1.2). This provides the first detailed study of early-type galaxy rotation at these redshifts. From surface brightness profiles from HST imaging we calculate two-integral oblate axisymmetric Jeans equation models for the observed kinematics. Fits to the data yield for each galaxy the degree of rotational support and the mass-to-light ratio M/L-Jeans. S0 and Sa galaxies are generally rotationally supported, whereas elliptical galaxies rotate less rapidly or not at all. Down to M-B - -19.5 (corrected for luminosity evolution), we find no evidence for evolution in the fraction of rotating early-type (E+S0) galaxies between z similar to 1 (63% +/- 11%) and the present (61% +/- 5%). We interpret this as evidence for little or no change in the field S0 fraction with redshift. We compare M/L-Jeans with M/L-vir inferred from the virial theorem and globally averaged quantities and assuming homologous evolution. There is good agreement for nonrotating (mostly E) galaxies. However, for rotationally supported galaxies (mostly S0) M/L-Jeans is on average similar to 40% higher than M/L-vir. We discuss possible explanations and the implications for the evolution of M/L between z = 1 and the present and its dependence on mass.},
  author       = {van der Wel, Arjen and Van Der Marel, Roeland P},
  issn         = {0004-637X},
  journal      = {ASTROPHYSICAL JOURNAL},
  keywords     = {MORPHOLOGY-DENSITY RELATION,TO-LIGHT RATIO,ELLIPTIC GALAXIES,FUNDAMENTAL PLANE,STAR-FORMATION,LENTICULAR GALAXIES,SAURON PROJECT,MASS-DISTRIBUTION,DYNAMICAL MODELS,Z=0.5 CLUSTERS,galaxies : elliptical and lenticular,cD,galaxies : evolution,galaxies : fundamental parameters,galaxies : kinematics and dynamics},
  language     = {eng},
  number       = {1},
  pages        = {260--269},
  title        = {Spatially resolved stellar kinematics of field early-type galaxies at z=1 : evolution of the rotation rate},
  url          = {http://dx.doi.org/10.1086/589734},
  volume       = {684},
  year         = {2008},
}

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