2012/06/12 by C. Chiosi, E. Merlin, Chiosi, Cesare +3 · 2 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Stellar, planetary, and galactic studies #Astrophysics and Star Formation Studies
paper · pdf · doi:10.48550/arxiv.1206.2532
Early-type galaxies obey a narrow relation traced by their stellar content between the mass and size (Mass- Radius relation). The wealth of recently acquired observational data essentially confirms the classical relations found by Burstein, Bender, Faber, and Nolthenius, i.e. log(R1/2) ∝ log(Ms)≃ 0.54 for high mass galaxies and log(R1/2) ∝ log(Ms) ≃ 0.3 for dwarf systems (shallower slope), where R1/2 and Ms are the half-light radius and total mass in stars, respectively. Why do galaxies follow these characteristic trends? What can they tell us about the process of galaxy formation? We investigate the mechanisms which concur to shape the Mass-Radius relation, in order to cast light on the physical origin of its slope, its tightness, and its zero point. We perform a theoretical analysis, and couple it with the results of numerical hydrodynamical (NB-TSPH) simulations of galaxy formation, and with a simulation of the Mass-Radius plane itself. We propose a novel interpretation of the Mass-Radius relation, which we claim to be the result of two complementary mechanisms: on one hand, the result of local physical processes, which fixes the ratio between masses and radii of individual objects; on the other hand, the action of cosmological global, statistical principles, which shape the distribution of objects in the plane. We reproduce the Mass-Radius relation with a simple numerical technique based on this view.