Research Interests: Galaxy Formation and Evolution
- Progenitors of Type Ia Supernovae (SNe Ia)
- NOT the double-degenerate but the single-degenerate scenario, where the progenitor is a pair of white dwarf and normal star.
- In terms of the evolution of the binary system, metallicity effect is important on the occurrence of SNe Ia (Kobayashi et al. 1998).
- The observed scatter of the SNIa luminosity can be explained (Umeda et al. 1999).
- The dust effect on the SNIa cosmology can be estimated (Totani & Kobayashi 1999).
- The cosmic SN Ia rate will show a decrease from z~1.5 (Kobayashi et al. 98, 00)
- The bimodarity in lifetime distribution has been prediced (Kobayashi & Nomoto 2008).
- Galactic and Cosmic Chemical Evolution
- Chemical abundances are fossils to tell us the star formation history of galaxies and the universe;
Stars formed from gas clouds in a galaxy, eject heavy elements into the interstellar medium via supernovae.
Different heavy elements are produced from different types of supernovae (SN Ia, II, and HN) with different timescales.
- Computed with one zone-models, with which I can make a galaxy in 2 minutes:) (Kobayashi, Tsujimoto, Nomoto 00)
- Computed with SPH simulations, which takes 2 weeks for a galaxy, 2 months for the Universe... (Kobayashi, Springel, White 06)
- Spatial Distribution of Heavy Elements in galaxies and the Universe
- The formation history of the galaxy is imprinted in such internal structure of the galaxy, which will be obtained with the Integral Field Spectrographs and Adaptive Optics.
- Metallicity gradients of nearby elliptical galaxies observed (Kobayashi & Arimoto 99).
- Color gradients of distant (z<1) elliptical galaxies observed (Tamura, Kobayashi, et al. 00).
- GRAPE-SPH Chemodynamical Simulation
- I've simulated the formation and evolution of more than a hundred elliptical galaxies from the CDM initial fluctuation. GRAPE is a Japan-made special computer to calculate gravity.
- By reproducing the observed variety of radial metallicity gradients, I conclude that not all ellipticals formed by major mergers, but some of them formed monolithically (Kobayashi 2004).
- The observed scaling relations and fundamental plane can be reproduced (Kobayashi 2005).
- Chemodynamical evolution of the Milky Way Galaxy for the Galactic Archaeology (Kobayashi, Nakasato, in prep.).
- Cosmic Chemical Enrichment with GADGET
- I've introduced my schemes of feedback and chemical enrichment into GADGET, which is widely used parallel SPH code, German-made.
- I succeed in blowing the galactic winds from a small disk galaxy, not by hand but by supernova thermal feedback.
- Cosmic SFRs, chemical evolution, mass-dependent galactic winds, and the mass-metallicity relation of galaxies are reproduced (Kobayashi, Springel, White 06).
- Origin of Galactic Morphology
- How did spiral and elliptical galaxies form? What are dwarf galaxies? What are DLA, LBG, ERO, DRG, BzK,...
- Environmental Effects
- Galaxy formation in fields vs clusters? Elemental abundance patterns of ICM?
- Hypernovae nucleosynthesis (Kobayashi, Umeda, Tominaga, et al. 06)
- Gamma-ray burst rates (Kobayashi, Maeda, in prep.)
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