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Abstract: The near orthogonal distributions of dwarf elliptical dE and giantelliptical E galaxies in the mu e-Mag and mu e-logR e diagrams have beeninterpreted as evidence for two distinct galaxy formation processes. However,continuous, linear relationships across the alleged dE-E boundary at M B = -18mag - such as those between central surface brightness mu 0 and i galaxymagnitude and ii light-profile shape n - suggest a similar, governingformation mechanism. Here we explain how these latter two linear trendsnecessitate a different behavior for dE and E galaxies, exactly as observed, indiagrams involving mu e and also e. A natural consequence is that thedistribution of dEs and Es in Fundamental Plane type analyses that use theassociated intensity I e, or e, are expected to appear different. Togetherwith other linear trends across the alleged dE-E boundary, such as thosebetween luminosity and color, metallicity, and velocity dispersion, it appearsthat the dEs form a continuous extension to the E galaxies. The presence ofpartially depleted cores in luminous M B < -20.5 mag Es does however signifythe action of a different physical process at the centers < ~300 pc of thesegalaxies.



Author: Alister W. Graham Swinburne University, Rafael Guzman Univ. of Florida

Source: https://arxiv.org/







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