Elemental Abundances across Cosmic Time

I show how chemical enrichment took place in the Milky Way and in a cosmic scale, using my hydrodynamical simulations that includes star formation and feedback from stars, supernovae, and active galactic nuclei (AGN). Thanks to nuclear astro-physics collaboration, we now have good understanding of the origin of elements from carbon to zinc, and theoretical models have well reproduced the observations of these elemental abundances in the Milky Way Galaxy. Some new observations challenge these models for a few elements, which is due to the problems in stellar astrophysics. In our cosmological simulations, we also include super-massive blackholes that originate the first stars, which had only ~100-1000 Msun initially, contrary to the merger products in other simulations. Our AGN cause large-scale metal outflows, which result in the enrichment of intergalactic medium, as well as the quenching of star formation in massive galaxies. The simulated results are in good agreement with many observations of galaxies, including cosmic star formation rates, blackhole mass-galaxy mass relation, size-mass relation, and mass-metallicity relations of galaxies (which evolve with a steeper slope at higher redshifts), and metallicity radial gradients within galaxies (which can trace the merging history of the galaxies). I also show elemental abundances at high-redshift galaxies, which can be used to understand the formation and evolution of galaxies.