1.65 MICRON (H BAND) SURFACE PHOTOMETRY OF GALAXIES. Ⅹ. STRUCTURAL AND DYNAMICAL PROPERTIES OF ELLIPTICAL GALAXIES

摘要

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 μm). 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 σ_0 into the virial rms velocity σ_(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.