학술논문
A Large Sample of Extremely Metal-poor Galaxies at $z<1$ Identified from the DESI Early Data
Document Type
Working Paper
Author
Zou, Hu; Sui, Jipeng; Saintonge, Amélie; Scholte, Dirk; Moustakas, John; Siudek, Malgorzata; Dey, Arjun; Juneau, Stephanie; Guo, Weijian; Canning, Rebecca; Aguilar, J.; Ahlen, S.; Brooks, D.; Claybaugh, T.; Dawson, K.; de la Macorra, A.; Doel, P.; Forero-Romero, J. E.; Gontcho, S. Gontcho A; Honscheid, K.; Landriau, M.; Guillou, L. Le; Manera, M.; Meisner, A.; Miquel, R.; Nie, Jundan; Poppett, C.; Rezaie, M.; Rossi, G.; Sanchez, E.; Schubnell, M.; Seo, H.; Tarle, G.; Zhou, Zhimin; Zou, Siwei
Source
Subject
Language
Abstract
Extremely metal-poor galaxies (XMPGs) at relatively low redshift are excellent laboratories for studying galaxy formation and evolution in the early universe. Much effort has been spent on identifying them from large-scale spectroscopic surveys or spectroscopic follow-up observations. Previous work has identified a few hundred XMPGs. In this work, we obtain a large sample of 223 XMPGs at $z<1$ from the early data of the Dark Energy Spectroscopic Instrument (DESI). The oxygen abundance is determined using the direct $T_{\rm e}$ method based on the detection of the [O III]$\lambda$4363 line. The sample includes 95 confirmed XMPGs based on the oxygen abundance uncertainty; remaining 128 galaxies are regarded as XMPG candidates. These XMPGs are only 0.01% of the total DESI observed galaxies. Their coordinates and other proprieties are provided in the paper. The most XMPG has an oxygen abundance of $\sim 1/34 Z_{\odot}$, stellar mass of about $1.5\times10^7 M_{\odot}$ and star formation rate of 0.22 $M_{\odot}$ yr$^{-1}$. The two most XMPGs present distinct morphologies suggesting different formation mechanisms. The local environmental investigation shows that XMPGs preferentially reside in relatively low-density regions. Many of them fall below the stellar mass-metallicity relations (MZRs) of normal star-forming galaxies. From a comparison of the MZR with theoretical simulations, it appears that XMPGs are good analogs to high-redshift star-forming galaxies. The nature of these XMPG populations will be further investigated in detail with larger and more complete samples from the on-going DESI survey.
Comment: accepted for publication in ApJ
Comment: accepted for publication in ApJ