1.65 micron (H band) surface photometry of galaxies. X. Structural and dynamical properties of elliptical galaxies

We analyze the structural and dynamical properties of a sample of 324 nearby elliptical and dwarf elliptical galaxies observed during an extensive near-IR survey in the H band (1.65 mum). The fundamental plane is determined and a significant tilt is assessed. The origins of such a tilt are investigated by means of a spherically symmetric, isotropic, pressure-supported dynamical model relying on the observed surface brightness profiles. The systematic variation of the shape coefficient converting the measured central velocity dispersion sigma(0) into the virial rms velocity sigma(rms) is found to be the main cause of the tilt, due to aperture effects. Moreover, the ratio between the dynamical mass M-dyn and the total H-band luminosity L-H turns out to be roughly constant along the luminosity sequence of ellipticals: H-band luminosity is therefore a reliable and cheap estimator of the dynamical mass of the E galaxies