Chemical evolution of disk galaxies in the local Universe using a new multiphase chemodynamical code Nicolas Champavert, Hervé Wozniak Centre de Recherche Astronomique de Lyon (CRAL)
Goals
Star Formation
We aim to study of the formation and evolution of galaxies with high spatial and temporal resolution, in cosmological context, in particular the chemical enrichment.
The gas is allowed to form star clusters from the cold phase if : • the mean gas temperature (cold + warm/hot phase) is low (T ≤ 104 K)
We have developed a new chemodynamical tool to describe the physical interplay between the stars and the multiphase interstellar medium in galaxies.
• the gas is unstable (Mg ≥ MJeans α Vs3/ρ1/2) • when a gas particle fills all these conditions, a star cluster is formed only after a delay proportional to the free-fall time (n tff with n constant)
We describe the code and our first results on the effects of the initial fraction of cold (100 K) gas on the star formation history and the chemical evolution of an axisymmetric disc.
• the mass of the star cluster formed is: Mgas/MJeans n tff SFRcluster (with SFRcluster = 10-3 Msol/yr)
ISM
Stellar population
We have implemented a two-phase ISM: To follow the stellar evolution (energy energy and mass losses from stellar winds and SNII), we use the evolutionary synthesis code Starburst99 v5.1 (Leitherer et al., 1999, ApJS, 123, 3 ; Vázquez & Leitherer, 2005, ApJ, 621, 695). In particular, it provides mass losses for 9 chemical elements (H, He, C, N, O, Mg, Si, S, Fe). Stellar clusters are represented with a SSP build from: • a Kroupa IMF with exponents (1.3, 2.3) and mass boundaries (0.1, 0.5, 100 Msol) • Padova evolutionary tracks for 5 metallicities (0.02 to 2.5 the solar metallicity) For the SNIa, we use the yields of Iwamoto et al., 1999, ApJS, 125, 439, the rates of Kobayashi et al., 2000, ApJ, 539, 26 and an energy of 1.5 1051 erg per SN.
Cooling/Heating Physical processes in the hot phase: • photoelectric heating from grains and PAHs (Wolfire et al., 1995, ApJ, 443, 152) • radiative cooling with Mappings III • thermal heating due to stellar feedback (winds, SNII, SNIa) We use Mappings III to model the cooling of the hot phase between 102 and 109K. We consider the hot phase as an optically thin gas (τ 106 K). The very hot gas (T>107 K) is mainly located into the halo (outside the central 10 kpc).
Maps of gas metallicity for the three runs. Mass distributions are overplotted with black contours. The metal enrichment of the gas mainly occurs inside the central 3 kpc where the star formation is active. The more star formation, the more metallic the gas becomes. For run C, after the first burst, star formation occurred only in the very central part (r
