EMPRESS. IV. Extremely Metal-poor Galaxies Including Very Low-mass Primordial Systems with M= 104-105Mand 2%-3% (O/H): High (Fe/O) Suggestive of Metal Enrichment by Hypernovae/Pair-instability Supernovae

Yuki Isobe, Masami Ouchi, Akihiro Suzuki, Takashi J. Moriya, Kimihiko Nakajima, Ken'Ichi Nomoto, Michael Rauch, Yuichi Harikane, Takashi Kojima, Yoshiaki Ono, Seiji Fujimoto, Akio K. Inoue, Ji Hoon Kim, Yutaka Komiyama, Haruka Kusakabe, Chien Hsiu Lee, Michael Maseda, Jorryt Matthee, Leo Michel-Dansac, Tohru NagaoThemiya Nanayakkara, Moka Nishigaki, Masato Onodera, Yuma Sugahara, Yi Xu

研究成果: Article査読

2 被引用数 (Scopus)

抄録

We present Keck/LRIS follow-up spectroscopy for 13 photometric candidates of extremely metal-poor galaxies (EMPGs) selected by a machine-learning technique applied to the deep (∼26 AB mag) optical and wide-area (∼500 deg2) Subaru imaging data in the EMPRESS survey. Nine out of the 13 candidates are EMPGs with an oxygen abundance (O/H) less than ∼10% solar value (O/H)⊙, and four sources are contaminants of moderately metal-rich galaxies or no emission-line objects. Notably, two out of the nine EMPGs have extremely low stellar masses and oxygen abundances of 5 × 104-7 × 105 M⊙ and 2%-3% (O/H)⊙, respectively. With a sample of five EMPGs with (Fe/O) measurements, two (three) of which are taken from this study (the literature), we confirm that two EMPGs with the lowest (O/H) ratios of ∼2% (O/H)⊙ show high (Fe/O) ratios of ∼0.1, close to the solar abundance ratio. Comparing galaxy chemical enrichment models, we find that the two EMPGs cannot be explained by a scenario of metal-poor gas accretion/episodic star formation history due to their low (N/O) ratios. We conclude that the two EMPGs can be reproduced by the inclusion of bright hypernovae and/or hypothetical pair-instability supernovae (SNe) preferentially produced in a metal-poor environment. This conclusion implies that primordial galaxies at z ∼10 could have a high abundance of Fe that did not originate from Type Ia SNe with delays and that Fe may not serve as a cosmic clock for primordial galaxies.

本文言語English
論文番号111
ジャーナルAstrophysical Journal
925
2
DOI
出版ステータスPublished - 2022 2月 1

ASJC Scopus subject areas

  • 天文学と天体物理学
  • 宇宙惑星科学

フィンガープリント

「EMPRESS. IV. Extremely Metal-poor Galaxies Including Very Low-mass Primordial Systems with M= 104-105Mand 2%-3% (O/H): High (Fe/O) Suggestive of Metal Enrichment by Hypernovae/Pair-instability Supernovae」の研究トピックを掘り下げます。これらがまとまってユニークなフィンガープリントを構成します。

引用スタイル