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arXiv · 2110.05030

Subaru/FOCAS IFU revealed the metallicity gradient of a local extremely metal-poor galaxy

Yuri Kashiwagi·Akio K. Inoue·Yuki Isobe·Kimihiko Nakajima·Masami Ouchi·Shinobu Ozaki·Seiji Fujiimoto·Yoshiaki Ono·Takashi Kojima
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Abstract

We present the first measurement of the metallicity gradient in extremely metal-poor galaxies (EMPGs). With Subaru/Faint Object Camera And Spectrograph (FOCAS) Integral Field Unit (IFU), we have observed a nearby, low-mass EMPG, HSC J1631+4426, whose oxygen abundance and stellar mass are known to be 12+log(O/H) $=6.9$ and $\log_{10}(M_*/{\rm M}_\odot)=5.8$, respectively. The measured metallicity gradient is $-0.36 \pm 0.04$ dex kpc$^{-1}$ corresponding to $-0.049 \pm 0.006$ dex R$_\mathrm{e}^{-1}$ for the continuum effective radius of $R_\mathrm{e} = 0.14$ kpc. Our observation has successfully demonstrated that three-dimensional spectroscopy with 8m-class telescopes is powerful enough to reveal the metallicity distribution in local EMPGs, providing precious information of the baryon cycle in local analogs of primordial galaxies in the early Universe.

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Yuri Kashiwagi, Akio K. Inoue, Yuki Isobe, Kimihiko Nakajima, Masami Ouchi, Shinobu Ozaki, Seiji Fujiimoto, Yoshiaki Ono, Takashi Kojima. 2021-10-11. Subaru/FOCAS IFU revealed the metallicity gradient of a local extremely metal-poor galaxy. https://doi.org/10.1093/pasj%2Fpsab100

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