EMPRESS. IV. Extremely Metal-poor Galaxies Including Very Low-mass Primordial Systems with M <SUB>*</SUB> = 10<SUP>4</SUP>-10<SUP>5</SUP> M <SUB>⊙</SUB> and 2%-3% (O/H): High (Fe/O) Suggestive of Metal Enrichment by Hypernovae/Pair-instability Supernovae - Archive ouverte HAL Access content directly
Journal Articles The Astrophysical Journal Year : 2022

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

, , , , , , , , , , , , , , , , , , (1) , , , , , ,
1
Yuki Isobe
  • Function : Author
Masami Ouchi
  • Function : Author
Akihiro Suzuki
  • Function : Author
Takashi J. Moriya
  • Function : Author
Kimihiko Nakajima
  • Function : Author
Ken'Ichi Nomoto
  • Function : Author
Michael Rauch
  • Function : Author
Yuichi Harikane
  • Function : Author
Takashi Kojima
  • Function : Author
Yoshiaki Ono
  • Function : Author
Seiji Fujimoto
  • Function : Author
Akio K. Inoue
  • Function : Author
Ji Hoon Kim
  • Function : Author
Yutaka Komiyama
  • Function : Author
Haruka Kusakabe
  • Function : Author
Chien-Hsiu Lee
  • Function : Author
Michael Maseda
  • Function : Author
Jorryt Matthee
  • Function : Author
Tohru Nagao
  • Function : Author
Themiya Nanayakkara
  • Function : Author
Moka Nishigaki
  • Function : Author
Masato Onodera
  • Function : Author
Yuma Sugahara
  • Function : Author
Yi Xu
  • Function : Author

Abstract

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.
Fichier principal
Vignette du fichier
Isobe_2022_ApJ_925_111.pdf (2.23 Mo) Télécharger le fichier
Origin : Publisher files allowed on an open archive

Dates and versions

insu-03711537 , version 1 (01-07-2022)

Licence

Attribution - CC BY 4.0

Identifiers

Cite

Yuki Isobe, Masami Ouchi, Akihiro Suzuki, Takashi J. Moriya, Kimihiko Nakajima, et al.. EMPRESS. IV. Extremely Metal-poor Galaxies Including Very Low-mass Primordial Systems with M * = 104-105 M and 2%-3% (O/H): High (Fe/O) Suggestive of Metal Enrichment by Hypernovae/Pair-instability Supernovae. The Astrophysical Journal, 2022, 925, ⟨10.3847/1538-4357/ac3509⟩. ⟨insu-03711537⟩
12 View
5 Download

Altmetric

Share

Gmail Facebook Twitter LinkedIn More