Session 7: Observational Astronomy

Title: Multiphase Chemodynamical Modeling of Galaxy Formation and Evolution
Author: P. Berczik

  Recent advances in computer technology and numerical methods have allowed detailed modeling of baryonic matter dynamics in a universe dominated by collisionless dark matter and, therefore, the detailed gravitational and hydrodynamical description of galaxy formation and evolution. As a main tool for this study we use our recent Multiphase Chemodynamical Smoothed Particle Hydrodynamics (MP-CD-SPH) code (Berczik, Hensler, Spurzem & Theis, 2001, A&A, in prep.). This complex code include the multiphase chemodynamical model of galaxy incorporated to the effective 3D SPH algorithm (Berczik, 1999, A&A,  348, 371; Berczik, 2000, A&SS, 271, 103). Our new modeling is include:
  1) Two component gas description of ISM (cold "clouds" and "smooth" warm phase) (Samland, Hensler & Theis, 1997, ApJ,  476,  544). The basic idea is making a two component gas contents and added to smooth and warm SPH component some cold cloudy gas fragments. This cold clumps modeled as a N-body particles with some viscosity (Theis & Hensler, 1993, A&A, 280, 85). The cloudy component interact with surrounding warm SPH gas also via condensation and evaporation processes (Kppen, Theis & Hensler, 1998, A&A, 331, 524).
  2) Original SF algorithm and description of "star" particles as a dynamically separate N-body particles. The cloud component phase of the gas is form the stars (due to cloud-cloud collisions) and after the stars returned to warm gas phase (due to SNII, SNIa and PN event) the chemically enriched gas material and energy.
  3) The code also includes the photometric evolution of each "star" particle, based on the idea of the Single Stellar Population (SSP). The SSP integrated colours (UBVRIKM) are taken from Tantalo, Chiosi, Bressan & Fagotto, 1996, A&A, {\bf 311}, 361. The spectro photometric evolution of the overall ensemble of "star" particles forms the Spectral nergy Distribution (SED) of the galaxy.
  As a test of our new MP--CD--SPH code, we calculate the star forming dwarf galaxy evolution. Because the mass of dwarf galaxies MGAL =108-1010 solar masses, even with relatively "small" number of cold "clouds" (~ 5,000 - 10,000) give to us the needed physical resolution for realistic description of individual molecular clouds.