EMPRESS. XII. Statistics on the Dynamics and Gas Mass Fraction of Extremely Metal-poor Galaxies

Yi Xu*, Masami Ouchi, Yuki Isobe, Kimihiko Nakajima, Shinobu Ozaki, Nicolas F. Bouché, John H. Wise, Eric Emsellem, Haruka Kusakabe, Takashi Hattori, Tohru Nagao, Gen Chiaki, Hajime Fukushima, Yuichi Harikane, Kohei Hayashi, Yutaka Hirai, Ji Hoon Kim, Michael V. Maseda, Kentaro Nagamine, Takatoshi ShibuyaYuma Sugahara, Hidenobu Yajima, Shohei Aoyama, Seiji Fujimoto, Keita Fukushima, Shun Hatano, Akio K. Inoue, Tsuyoshi Ishigaki, Masahiro Kawasaki, Takashi Kojima, Yutaka Komiyama, Shuhei Koyama, Yusei Koyama, Chien Hsiu Lee, Akinori Matsumoto, Ken Mawatari, Takashi J. Moriya, Kentaro Motohara, Kai Murai, Moka Nishigaki, Masato Onodera, Yoshiaki Ono, Michael Rauch, Tomoki Saito, Rin Sasaki, Akihiro Suzuki, Tsutomu T. Takeuchi, Hiroya Umeda, Masayuki Umemura, Kuria Watanabe, Kiyoto Yabe, Yechi Zhang

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

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 vrot0 < 1 suggesting dispersion-dominated systems. There is a clear decreasing trend of vrot0 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 vrot0 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 languageEnglish
Article number49
JournalAstrophysical Journal
Volume961
Issue number1
DOIs
Publication statusPublished - 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

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