Abstract
We present the demography of the dynamics and gas mass fraction of 33 extremely metal-poor galaxies (EMPGs) with metallicities of 0.015–0.195 Ze and low stellar masses of 104–108 Me in the local universe. We conduct deep optical integral field spectroscopy (IFS) for the low-mass EMPGs with the medium-high resolution (R = 7500) grism of the 8 m Subaru FOCAS IFU instrument by the EMPRESS 3D survey, and investigate the Hα emission of the EMPGs. Exploiting the resolution high enough for the low-mass galaxies, we derive gas dynamics with the Hα lines by the fitting of three-dimensional disk models. We obtain an average maximum rotation velocity (vrot) of 15 ± 3 km s−1 and an average intrinsic velocity dispersion (σ0) of 27 ± 10 km s−1 for 15 spatially resolved EMPGs out of 33 EMPGs, and find that all 15 EMPGs have vrot/σ0 < 1 suggesting dispersion-dominated systems. There is a clear decreasing trend of vrot/σ0 with the decreasing stellar mass and metallicity. We derive the gas mass fraction (fgas) for all 33 EMPGs, and find no clear dependence on stellar mass and metallicity. These vrot/σ0 and fgas trends should be compared with young high-z galaxies observed by the forthcoming JWST IFS programs to understand the physical origins of the EMPGs in the local universe.
Original language | English |
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Article number | 49 |
Journal | Astrophysical Journal |
Volume | 961 |
Issue number | 1 |
DOIs | |
Publication status | Published - 2024 Jan 1 |
Keywords
- Dwarf galaxies (416)
- Galaxy dynamics (591)
- Galaxy kinematics (602)
- Unified Astronomy Thesaurus concepts: Galaxy evolution (594)
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science