124 research outputs found
Modeling Formation of Globular Clusters: Beacons of Galactic Star Formation
Modern hydrodynamic simulations of galaxy formation are able to predict
accurately the rates and locations of the assembly of giant molecular clouds in
early galaxies. These clouds could host star clusters with the masses and sizes
of real globular clusters. I describe current state-of-the-art simulations
aimed at understanding the origin of the cluster mass function and metallicity
distribution. Metallicity bimodality of globular cluster systems appears to be
a natural outcome of hierarchical formation and gradually declining fraction of
cold gas in galaxies. Globular cluster formation was most prominent at
redshifts z>3, when massive star clusters may have contributed as much as 20%
of all galactic star formation.Comment: Proceedings of IAU Symposium 270, Computational Star Formation,
Barcelona, June 201
Contraction of Dark Matter Halos in Response to Condensation of Baryons
The cooling of baryons in the centers of dark matter halos leads to a more
concentrated dark matter distribution. This effect has traditionally been
calculated using the model of adiabatic contraction, which assumes spherical
symmetry, while in hierarchical formation scenarios halos grow via multiple
violent mergers. We test the adiabatic contraction model in high-resolution
cosmological simulations and find that the dissipation of gas indeed increases
the density of dark matter and steepens its radial profile compared to the case
without cooling. Although the standard model systematically overpredicts the
increase of dark matter density, a simple modification of the assumed invariant
from M(r)r to M()r, where is the orbit-averaged particle position,
reproduces the simulated profiles within 10%.Comment: 6 pages, invited talk at the XXI IAP Colloquium, Paris, July 200
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