Galactic archeology and the origin of the elements

  • Datum: –15.00
  • Plats: Online: Zoom
  • Föreläsare: Chiaki Kobayashi
  • Arrangör: Instutionen för fysik och astronomi avdelningen för astronomi och rymdfysik
  • Kontaktperson: Sofia Ramstedt
  • Seminarium

Evolution av ämnen i galaxen. Seminariet sker på engelska.

Galactic chemical evolution (GCE) can provide stringent constraints not only on nuclear astrophysics but also on the formation and evolutionary history of the Milky Way itself, through an approach called Galactic archeology. We construct GCE models for all stable elements from C (A = 12) to U (A = 238) from first principles, i.e., using theoretical nucleosynthesis yields and event rates of all chemical enrichment sources. This enables us to predict the origin of the elements in the periodic table as a function of time, which, for example, has revealed the "missing gold" problem. I also apply these yields to more realistic chemo-hydrodynamical simulations of a Milky Way type galaxy, to discuss the evolution of the Galactic sub-structures and their elemental abundances. The simulated galaxy disc grows from the inside out, with a radial gradient in the star formation rate during the entire phase, but with a universal profile for the outflow-to-infall ratio. The simulated disc undergoes two modes of gas inflows: (i) an infall of metal-poor and relatively low-[alpha/Fe] gas, and (ii) a radial flow where already chemically-enriched gas moves inwards with an average velocity of ~0.7 km/s. Stellar migrations mostly happen outwards, which flattens the radial metallicity profiles by 0.05 dex/kpc in the slopes, on typical timescales of ~5 Gyr after the onset of star formation.