Contatto di riferimento: Donatella Romano
Partecipanti: Chiaki Kobayashi (Centre for Astrophysics Research, University of Hertfordshire, UK)
Abstract
Star formation and chemical enrichment histories of galaxies are imprinted in
their internal structures of galaxies, i.e., kinematics and elemental
abundances of stars within galaxies. We predict the distribution of elements
within galaxies using our chemodynamical simulations. In the simulated Milky
Way-type galaxies, the bulge formed though assembly of gas-rich galaxies at
high-redshifts, and has old, metal-rich, and alpha-enhanced populations. The
disk formed inside-out over Cosmic time, producing [alpha/Fe]-[Fe/H] relations.
A half of thick disk stars have formed in satellite galaxies. In each
component, the scatter in elemental abundance ratios is caused by this
accretion as well as migration and in-situ variation of chemical enrichment.
In cosmological simulations, the feedback from active galactic nuclei (AGN)
plays an essential role in questing star formation in massive galaxies and
re-distributing metals into the intergalactic medium. We have applied a new AGN
model for the formation of black holes motivated by the first star formation,
in contrast to the merging scenario of previous works. Our simulations
reproduce the observed cosmic star formation rates, black hole mass-galaxy mass
relation, size-mass relation, and mass-metallicity relation of galaxies, and
are in better agreement with the observed down-sizing phenomena, namely, the
alpha enhancement of early-type galaxies. We also predict the time evolution of
these relations and the metallicity radial gradients. At present, stellar
metallicity gradients dramatically evolve depending on their merging histories,
while gas-phase metallicity gradients are more sensitive to the AGN feedback.
See you on thursday in the seminars’ room, floor -1, via Ranzani 1, on time at 14:00.
Next seminars:
* Thursday December 10th, at 14:00 Corrado Boeche (University of Heidelberg, DE)
* Wednesday December 16th, at 14:00 Rodrigo Ibata (Observatoire de Strasbourg, FR)
* Thursday December 17th, at 14:00 Elena M. Rossi (Leiden Univ., NL)
The complete list of seminars is available at: http://davide2.bo.astro.it/?page_id=4531
The organizers of seminars: