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Title: Properties of the Lowest-metallicity Galaxies over the Redshift Range z = 0.2 to z = 1
Abstract Low-metallicity galaxies may provide key insights into the evolutionary history of galaxies. Galaxies with strong emission lines and high equivalent widths (rest-frame EW(H β ) ≳ 30 Å) are ideal candidates for the lowest-metallicity galaxies to z ∼ 1. Using a Keck/DEIMOS spectral database of about 18,000 galaxies between z = 0.2 and z = 1, we search for such extreme emission-line galaxies with the goal of determining their metallicities. Using the robust direct T e method, we identify eight new extremely metal-poor galaxies (XMPGs) with 12 + log O/H ≤7.65, including one at 6.949 ± 0.091, making it the lowest-metallicity galaxy reported to date at these redshifts. We also improve upon the metallicities for two other XMPGs from previous work. We investigate the evolution of H β using both instantaneous and continuous starburst models, finding that XMPGs are best characterized by continuous starburst models. Finally, we study the dependence on age of the buildup of metals and the emission-line strength.  more » « less
Award ID(s):
1715145
PAR ID:
10353699
Author(s) / Creator(s):
; ; ;
Date Published:
Journal Name:
The Astrophysical Journal
Volume:
935
Issue:
2
ISSN:
0004-637X
Page Range / eLocation ID:
150
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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