The 18th International Symposium on Origin of Matter and Evolution of Galaxies (OMEG18)

Extra-galactic archaeology - elemental abundances of high-z galaxies

Oct 21, 2026, 11:40 AM

25m

Headquarters Building 2F (RIKEN)

Invited Presentation First-generation stars and galactic chemical evolution Scientific Session

Speaker

Chiaki Kobayashi (University of Hertfordshire)

Description

Extra-galactic archaeology - elemental abundances of high-z galaxies

The James Webb Space Telescope (JWST) is expected to find the first galaxies - those hosting metal-free stars. Surprisingly, though, galaxies with strong metal lines have been detected indicating unusual chemical composition (e.g. high N/O ratio). Nitrogen can be enhanced not only by asymptotic giant branch (AGB) stars but also Wolf-Rayet (WR) stars. I show galactic chemical evolution models that can naturally reproduce N emitters with intermittent star formation. Wolf-Rayet stars are expected to enhance Fluorine as well. With Atacama Large Millimeter/submillimeter Array (ALMA), we show two submillimeter galaxies, one at z=4.4 with a high F abundance, while another at z=6.0 with no F enhancement, which further supports the intermittent star formation in early Universe. Although these do not require changing the initial mass function (IMF), I will discuss how other elements (C and Ar) can be used to constrain the IMF and the first stars.