Massive galaxies at high z: Assembly patterns, structure, and dynamics in the fast phase of galaxy formation

Astrophysical Journal Letters 732.2 (2011): L32 reproduced by permission of the AAS
Relaxed, massive galactic objects have been identified at redshifts z = 4, 5, and 6 in hydrodynamical simulations run in a large cosmological volume. This allowed us to analyze the assembly patterns of the high-mass end of the galaxy distribution at these high z's, by focusing on their structural and dynamical properties. Our simulations indicate that massive objects at high redshift already follow certain scaling relations. These relations define virial planes at the halo scale, whereas at the galactic scale they define intrinsic dynamical planes that are, however, tilted relative to the virial plane. Therefore, we predict that massive galaxies must lie on fundamental planes from their formation. We briefly discuss the physical origin of the tilt in terms of the physical processes underlying massive galaxy formation at high z, in the context of a two-phase galaxy formation scenario. Specifically, we have found that it lies on the different behavior of the gravitationally heated gas as compared with cold gas previously involved in caustic formation and the mass dependence of the energy available to heat the gas.
This work was partially supported by the DGES (Spain) through the grants AYA2009-12792-C03-02 and AYA-2009-12792-C03-03, as well as by the ASTROMADRID network (CAM S2009/ESP-1496). A.K. and J.O. were supported by the MICINN, Spain, through the Ramon y Cajal programme and the “Supercomputación y e-Ciencia” Consolider-Ingenio 2010 project (CSD2007-0050), respectively.