JULIO F. NAVARRO
RESEARCH INTERESTS
My research interests concern the study
of the formation and evolution of galaxies and
galaxy clusters, with particular emphasis
on their cosmological origin as well as on the structure and dynamics of
their stellar, gaseous, and dark matter components.
Many of these complex issues are
best addressed using direct numerical simulations, for which I have developed
a general purpose, gridless, fully Lagrangian code well suited for evolving
a mixture of collisionless and collisional fluids in three dimensions.
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The code combines a fast tree-based
algorithm for the computation of gravitational N-body interactions with
the Smooth Particle Hydrodynamics (SPH) approach to numerical hydrodynamics.
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It can also take full advantage of
the GRAPE boards, which can speed-up the calculation of gravitational accelerations
by about one order of magnitude. I currently have access to a dual-CPU
UltraSparc2 workstation with 2 GRAPE boards attached to it through
a SolFlower Sbus-VME interface.
Applications of this code to the formation
of dark matter halos, galactic
disks, and X-ray clusters have highlighted
a number of successes and shortcomings of hierarchical theories of structure
formation.
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The baryon content of galaxy clusters
can be combined with primordial nucleosynthesis calculations to provide
strong constraints on the value of the density parameter Omega.
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Simple models of the intracluster medium
based on the gravitational collapse of non-radiative gas within evolving
dark matter halos cannot explain the observed structure and evolution of
X-ray clusters, and stress the importance of non-gravitational processes
such as radiative cooling and energy feedback from galaxy formation in
the evolution of the intracluster medium.
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The density profiles of dark matter
halos have a ``universal shape'', independent of the mass of the halo,
of the spectrum of initial density fluctuations, and of the cosmological
parameters. This remarkable structural similarity can be used in observational
studies of the mass profiles of galaxies and galaxy clusters to constrain
cosmological models.
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Our N-body/gasdynamical simulations
have highlighted the importance of feedback from evolving stars and supernovae
during galaxy formation. Without feedback, most of the baryons in the universe
would be locked up in galaxies, in disagreement with observations. Furthermore,
the spin of these galaxies would be much lower than inferred from observations
of spiral galaxies because of large angular momentum losses incurred during
the merger events that characterize the hierarchical buildup of galactic
systems.
Links
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A
hot link to a hot place:--Matthias
Steinmetz' website at the University of Arizona. Visit for a dose of
movies, cool pictures, and other nice stuff on our research on galaxy formation.
Movies
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You
can also see here Matthias Steinmetz' movie on galaxy
formation, if you have MpegTV.
INTERESTED IN MORE DETAILS?
Foreword
Galaxy Formation through Hierarchical Clustering
The Structure of Dark Matter Halos
The Formation and Evolution of X-Ray Clusters
