A two-phase scenario for bulge assembly in ΛcDM cosmologies
EntityUAM. Departamento de Física Teórica
PublisherThe American Astronomical Society
10.1088/0004-637X/763/1/26The Astrophysical Journal 763.1 (2013): 26
ISSN0004-637X (print); 1538-4357 (online)
Funded byThis work was partially supported by the MICINN (Spain) through the grants AYA2009-12792-C03-02 and AYA2009-12792-C03-03 from the PNAyA, as well as by the regional Madrid V PRICIT program through the ASTROMADRID network (CAM S2009/ESP-1496) and the “Supercomputación y e-Ciencia” Consolider-Ingenio CSD2007-0050 project.
ProjectComunidad de Madrid. S2009/AGR-1496/ASTROMADRID
SubjectsCosmology: theory; Galaxies: bulges; Galaxies: formation; Galaxies: kinematics and dynamics; Galaxies: star formation; Methods: numerical; Física
NoteThe Astrophysical Journal 763.1 (2013): 26 reproduced by permission of the AAS
Rights© 2013. The American Astronomical Society.
We analyze and compare the bulges of a sample of L* spiral galaxies in hydrodynamical simulations in a cosmological context, using two different codes, P-DEVA and GASOLINE. The codes regulate star formation in very different ways, with P-DEVA simulations inputting low star formation efficiency under the assumption that feedback occurs on subgrid scales, while the GASOLINE simulations have feedback that drives large-scale outflows. In all cases, the marked knee shape in mass aggregation tracks, corresponding to the transition from an early phase of rapid mass assembly to a later slower one, separates the properties of two populations within the simulated bulges. The bulges analyzed show an important early starburst resulting from the collapse-like fast phase of mass assembly, followed by a second phase with lower star formation, driven by a variety of processes such as disk instabilities and/or mergers. Classifying bulge stellar particles identified at z = 0 into old and young according to these two phases, we found bulge stellar sub-populations with distinct kinematics, shapes, stellar ages, and metal contents. The young components are more oblate, generally smaller, more rotationally supported, with higher metallicity and less alpha-element enhanced than the old ones. These results are consistent with the current observational status of bulges, and provide an explanation for some apparently paradoxical observations, such as bulge rejuvenation and metal-content gradients observed. Our results suggest that bulges of L* galaxies will generically have two bulge populations that can be likened to classical and pseudo-bulges, with differences being in the relative proportions of the two, which may vary due to galaxy mass and specific mass accretion and merger histories.
Google Scholar:Obreja, Aura Catalina - Domínguez Tenreiro, Rosa María - Brook, Chris B A - Martínez-Serrano, F. J. - Doménech-Moral, M. - Serna, Arturo - Mollá, Mercedes L. - Stinson, Gregory S.
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