Abstract
A magnitude-limited sample of nearly 9000 early-type galaxies in the redshift range 0.01 ≤ z ≤ 0.3 was selected from the Sloan Digital Sky Survey (SDSS) using morphological and spectral criteria. The fundamental plane relation in this sample is Ro ∝ σ1.49±0.05I in the r* band. It is approximately the same in the g*, i*, and z* bands. Relative to the population at the median redshift in the sample, galaxies at lower and higher redshifts have evolved only a little. If the fundamental plane is used to quantify this evolution, then the apparent magnitude limit can masquerade as evolution; once this selection effect has been accounted for, the evolution is consistent with that of a passively evolving population that formed the bulk of its stars about 9 Gyr ago. One of the principal advantages of the SDSS sample over previous samples is that the galaxies in it lie in environments ranging from isolation in the field to the dense cores of clusters. The fundamental plane shows that galaxies in dense regions are slightly different from galaxies in less dense regions.
Highlights
5640 South Ellis Avenue, Chicago, IL 60637. 2 Department of Physics, Carnegie Mellon University, 5000 ForbesAvenue, Pittsburgh, PA 15213. 3 Fermi National Accelerator Laboratory, P.O
Our results indicate that inferences about evolution that are based on this test depend uncomfortably strongly on the strength of selection effects, and on what one assumes for the fiducial shape of the fundamental plane (FP)
A more efficient way of seeing if the properties of galaxies depend on environment is to show the residuals from the FP. This efficiency comes at a cost: if the residuals correlate with environment, it is difficult to decide if the correlation is due to changes in luminosity, size, or velocity dispersion
Summary
Pittsburgh, PA 15213. 3 Fermi National Accelerator Laboratory, P.O. Box 500, Batavia, IL 60510. 4 Department of Physics and Astronomy, University of Pittsburgh, 3941. 4 Department of Physics and Astronomy, University of Pittsburgh, 3941. 22 Department of Astronomy and Astrophysics, 525 Davey Laboratory, Pennsylvania State University, University Park, PA 16802 This is the third of four papers in which the properties of $9000 early-type galaxies in the redshift range 0.01 z 0.3 are studied. Paper II (Bernardi et al 2003b) shows that the joint distribution of early-type galaxy luminosities, radii, and velocity dispersions is reasonably well fitted by a trivariate Gaussian. It shows various correlations between pairs of variables, such as the luminosity–velocity dispersion relation, the luminosity-size relation, and the relation between radius and surface brightness. Our convention is to set R log Ro and V log , where Ro and are effective radii in hÀ701 kpc and velocity dispersions in kilometers per second, respectively
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