Résumé / Abstract Seminaire_IAP
« Dissipational Relics in the Formation of Elliptical Galaxies »

Lars Hernquist
Harvard-Smithsonian Center for Astroph. (CfA) (Cambridge, Massachusetts, Etats-Unis d'Amérique)

Traditionally, it has been thought that elliptical galaxies originated primarily in a dissipationless manner, because these objects are deficient in gas relative to spirals and are spheroidal in shape, unlike galaxies with thin disks. Within the context of the merger hypothesis for the formation of ellipticals, it has long been recognized that mergers between pure stellar disks with properties similar to those of nearby galaxies cannot account for the high phase space densities of ellipticals. In this talk, I describe simulations exploring the consequences of dissipation in building elliptical galaxies through mergers and signatures of this process in their observed properties.
In particular, in major mergers between gas-rich disks, strong inflows of gas into the centers of remnants can be excited, explaining the high star formation rates inferred in ultraluminous infrared galaxies and fueling the growth of supermassive black holes. The interplay between black hole fueling and associated feedback effects makes these objects briefly visible as bright optical quasars before they evolve into passive galaxies with global properties similar to elliptical galaxies. The relic signatures of this evolutionary process can be seen in the light profiles of observed ellipticals, which exhibit a two-component structure, and through correlations between supermassive black holes and their hosts. The simulations provide a physical basis for understanding the formation of ellipticals and demonstrate that dissipation played a crucial role in establishing the fundamental plane of elliptical galaxies and in determining the compact nature of these objects at high redshifts.
vendredi 22 mai 2009 - 11:00
Salle des séminaires Évry Schatzman, Institut d'Astrophysique de Paris
Page web du séminaire / Seminar's webpage