Near-Infrared Imaging of Early-Type Galaxies. IV. The Physical Origins of the Fundamental Plane Scaling Relations

• Published in: The Astronomical journal 1998-10, Vol.116 (4), p.1606-1625
• Main Authors: Pahre, Michael A, de Carvalho, Reinaldo R, Djorgovski, S. G
• Format: Article
• Language: English
• ISSN: 1538-3881; 0004-6256; 1538-3881
• DOI: 10.1086/300545

The physical origins of the fundamental plane (FP) scaling relations are investigated using large samples of early-type galaxies observed at optical and NIR wavelengths. The slope alpha in the FP relation r(eff) is shown to increase systematically with wavelength from the U band through the K band. A distance-independent construction of the observables is described that provides an accurate measurement of the change in the FP slope between any pair of bandpasses. The variation of the FP slope with wavelength is strong evidence of systematic variations in stellar content along the elliptical galaxy sequence, but is insufficient to discriminate between a number of simple models for possible physical origins of the FP. The intercept of the diagnostic relationship between log D(K)/D(V) and log sigma(0) shows no significant dependence on environment, demonstrating the universality of the stellar population contributions at the level of (V - K) = 0.03 mag to the zero point of the global scaling relations. Several other constraints on the properties of early-type galaxies are included to construct an empirical, self-consistent model that provides a complete picture of the underlying physical properties that are varying along the early-type galaxy sequence. This empirical approach nonetheless demonstrates that there are significant systematic variations in both age and metallicity along the elliptical galaxy sequence, and that a small, but systematic, breaking of dynamical homology is required. (Author)