Numerical Simulations of Galaxy Formation in a LCDM Universe Mario G. Abadi Observatorio Astronómico De La Universidad Nacional De Córdoba CONICET, Argentina Collaborators: Julio Navarro: University of Victoria, Canada Matthias Steinmetz: Astrophysikalisches Institute, Postdam, Germany Vincent Eke: University of Durham, United Kingdom Andres Meza: Universidad de Chile, Santiago, Chile Amina Helmi: Kapteyn Astronomical Institute, Groningen, Netherlands
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Numerical Simulations of Galaxy Formation in a LCDM Universe Mario G. Abadi Observatorio Astronómico De La Universidad Nacional De Córdoba CONICET, Argentina.
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Numerical Simulations of Galaxy Formation in a LCDM Universe
Mario G. AbadiObservatorio Astronómico De La Universidad Nacional De Córdoba
CONICET, Argentina
Collaborators:
Julio Navarro: University of Victoria, Canada
Matthias Steinmetz: Astrophysikalisches Institute, Postdam, Germany
Vincent Eke: University of Durham, United Kingdom
Andres Meza: Universidad de Chile, Santiago, Chile
Amina Helmi: Kapteyn Astronomical Institute, Groningen, Netherlands
●WMAP and LSS results have established LCDM model as the new paradigm of hierarchical structure formation●Low mass density but flat scenario●Fully specified by the following cosmological parameters:● Constituents 70% dark energy, 26% dark matter and 4% baryons●Amplitude of mass fluctuation in spheres of 8 Mpc/h is given by RMS=0.9 and a Hubble´s constant h=0.7with no tilt in the initial power spectrum ●Success in LS (>1mpc) closer to linear regime
LCDM Universe
Galaxy Formation
● Observed disk at odds with ”natural” trends of hierarchical models
● Difficult to reconcile the early collapse and eventful merging history with dynamical clues
which point to a smooth assembly of disks
● Fragility of disks to rapid fluctuations of the gravitational potential such as those stirred by
mergers or satellite accretion events
● Dominant, cold, thin, stellar disks points to a histoty of mass accretion where major mergers
have player a minor role
● Age of oldest disk stars used to estimate the epoch of the last major merger (14 gyrs in the
solar neighborhood)
● Milky Way’s thick disk has its origin in an early thin disk of velocity and size comparable to
today’s but “thickened” by the accretion of a satellite
Numerical Simulations
• Initial conditions given by the lambda CDM model
• Astrophysics: gravitation, hydrodynamics, radiative cooling, star
formation, feedback and metals
• Initially only dark matter and gas particles
• Gas particles transformed in star particles
• 8 simulations finished with M~ 1-2x10^11 solar masses and N~0.6-