Early-Type Galaxies in the Sloan Digital Sky Survey. III. The Fundamental Plane

A magnitude limited sample of nearly 9000 early-type galaxies, in theredshift range 0.01 < z < 0.3, was selected from the Sloan Digital Sky Surveyusing morphological and spectral criteria. The Fundamental Plane relation inthis sample is R_o ~ sigma^{1.49\pm 0.05} I_o^{-0.75\pm 0.01} in the r* band.It is approximately the same in the g*, i* and z* bands. Relative to thepopulation at the median redshift in the sample, galaxies at lower and higherredshifts have evolved only little. If the Fundamental Plane is used toquantify this evolution then the apparent magnitude limit can masquerade asevolution; once this selection effect has been accounted for, the evolution isconsistent with that of a passively evolving population which formed the bulkof its stars about 9 Gyrs ago. One of the principal advangtages of the SDSSsample over previous samples is that the galaxies in it lie in environmentsranging from isolation in the field to the dense cores of clusters. TheFundamental Plane shows that galaxies in dense regions are slightly differentfrom galaxies in less dense regions.Comment: 27 pages, 10 figures. Accepted by AJ (scheduled for April 2003). This paper is part III of a revised version of astro-ph/011034