Oral Presentation
Kinematics of galaxies with early star formation explored by IFU observations of local Extremely Metal-Poor Galaxies
Presenter: Yi Xu (University of Tokyo)
Formation of the first galaxies is one of the most important topics in galaxy evolution. Due to observational limitations, the physical processes associated with the early galaxy formation at high z still remain open questions. We investigate extremely metal-poor galaxies (EMPGs) in the local universe that are analogs of the first galaxies. In the EMPRESS 3D project (PI: M. Ouchi), we have carried out deep optical spectroscopy for 27 EMPGs with the medium-high resolution grism (R~7500) of Subaru/FOCAS-IFU to spatially resolve the ionized gas kinematics. We model the 3-dimensional data cube with a rotation disk and derive the maximum rotation velocity. We find the maximum rotation velocity is smaller than the velocity dispersion, which suggests EMPGs may be dispersion dominated. We also estimate the gas mass fraction based on the Kennicutt-Schmidt law. We find EMPGs have decreasing velocity/dispersion and increasing gas mass fraction with decreasing stellar mass and metallicity. The correlations can be explained by stochastic gas inflows which triggers the recent star formation. Whether first galaxies at high z have similar kinematical features remains to be answered by the forthcoming JWST observations.
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