The Fundamental Scaling Relations of Elliptical Galaxies

(ABRIDGED) We examine the fundamental scaling relations of ellipticalgalaxies formed through mergers. Using hundreds of simulations to judge theimpact of progenitor galaxy properties on merger remnants, we find that gasdissipation provides an important contribution to tilt in the Fundamental Planerelation. Dissipationless mergers of disks produce remnants that occupy thevirial plane. As the gas content of disk galaxies is increased, the tilt of theFundamental Plane relation increases and the slope of the Re-M_* relationsteepens. For gas fractions fgas > 30%, the simulated Fundamental Planescalings approach those observed in the K-band. In our simulations, feedbackfrom supermassive black hole growth has only a minor influence on thestellar-mass scaling relations of spheroidal galaxies, but may play a role inmaintaining the observed Fundamental Plane tilt at optical wavelengths bysuppressing residual star formation in merger remnants. We estimate that \approx 40-100% of the Fundamental Plane tilt induced bystructural properties owes to trends in the central total-to-stellar mass ratioM_total/M_* produced by dissipation. Lower mass systems obtain greater phase-space densities than higher mass systems, producing a galaxy mass-dependentcentral M_total/M_* and a corresponding tilt in the Fundamental Plane.Comment: Version accepted by ApJ, 20 pages, 18 figures, resolution reduced for siz