학술논문
EMPRESS. XII. Statistics on the Dynamics and Gas Mass Fraction of Extremely-Metal Poor Galaxies
Document Type
Working Paper
Author
Xu, Yi; Ouchi, Masami; Isobe, Yuki; Nakajima, Kimihiko; Ozaki, Shinobu; Bouché, Nicolas F.; Wise, John H.; Emsellem, Eric; Kusakabe, Haruka; Hattori, Takashi; Nagao, Tohru; Chiaki, Gen; Fukushima, Hajime; Harikane, Yuichi; Hayashi, Kohei; Hirai, Yutaka; Kim, Ji Hoon; Maseda, Michael V.; Nagamine, Kentaro; Shibuya, Takatoshi; Sugahara, Yuma; Yajima, Hidenobu; Aoyama, Shohei; Fujimoto, Seiji; Fukushima, Keita; Hatano, Shun; Inoue, Akio K.; Ishigaki, Tsuyoshi; Kawasaki, Masahiro; Kojima, Takashi; Komiyama, Yutaka; Koyama, Shuhei; Koyama, Yusei; Lee, Chien-Hsiu; Matsumoto, Akinori; Mawatari, Ken; Moriya, Takashi J.; Motohara, Kentaro; Murai, Kai; Nishigaki, Moka; Onodera, Masato; Ono, Yoshiaki; Rauch, Michael; Saito, Tomoki; Sasaki, Rin; Suzuki, Akihiro; Takeuchi, Tsutomu T.; Umeda, Hiroya; Umemura, Masayuki; Watanabe, Kuria; Yabe, Kiyoto; Zhang, Yechi
Source
The Astrophysical Journal, Volume 961, Number 1, January 2024, Page 49-53
Subject
Language
Abstract
We present demography of the dynamics and gas-mass fraction of 33 extremely metal-poor galaxies (EMPGs) with metallicities of $0.015-0.195~Z_\odot$ and low stellar masses of $10^4-10^8~M_\odot$ 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 8m-Subaru FOCAS IFU instrument by the EMPRESS 3D survey, and investigate H$\alpha$ emission of the EMPGs. Exploiting the resolution high enough for the low-mass galaxies, we derive gas dynamics with the H$\alpha$ lines by the fitting of 3-dimensional disk models. We obtain an average maximum rotation velocity ($v_\mathrm{rot}$) of $15\pm3~\mathrm{km~s^{-1}}$ and an average intrinsic velocity dispersion ($\sigma_0$) of $27\pm10~\mathrm{km~s^{-1}}$ for 15 spatially resolved EMPGs out of the 33 EMPGs, and find that all of the 15 EMPGs have $v_\mathrm{rot}/\sigma_0<1$ suggesting dispersion dominated systems. There is a clear decreasing trend of $v_\mathrm{rot}/\sigma_0$ with the decreasing stellar mass and metallicity. We derive the gas mass fraction ($f_\mathrm{gas}$) for all of the 33 EMPGs, and find no clear dependence on stellar mass and metallicity. These $v_\mathrm{rot}/\sigma_0$ and $f_\mathrm{gas}$ 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.
Comment: 18 pages, 9 figures, accepted for publication in ApJ
Comment: 18 pages, 9 figures, accepted for publication in ApJ