JWST/NIRSpec Measurements of Extremely Low Metallicities in High Equivalent Width Lyα Emitters

Article Article scientifique Article JWST/NIRSpec Measurements of Extremely Low Metallicities in High Equivalent Width Lyα Emitters eng 2023-10-03 2023-10-01 author Maseda Michael V. 0000-0003-0695-4414 author Lewis Zach author Matthee Jorryt 0000-0003-2871-127X author Hennawi Joseph F. 0000-0002-7054-4332 author Boogaard Leindert 0000-0002-3952-8588 author Feltre Anna author Nanayakkara Themiya 0000-0003-2804-0648 author Bacon Roland author Barger Amy 0000-0002-3306-1606 author Brinchmann Jarle 0000-0003-4359-8797 author Franx Marijn 0000-0002-8871-3026 author Hashimoto Takuya 0000-0002-0898-4038 author Inami Hanae 0000-0003-4268-0393 author Kusakabe Haruka 0000-0002-3801-434X 918882 author Leclercq Floriane author Rowland Lucie author Taylor Anthony J. 0000-0003-1282-7454 author Tremonti Christy author Urrutia Tanya 0000-0001-6746-9936 author Schaye Joop 0000-0002-0668-5560 author Simmonds Charlotte author Vitte Eloïse Aurélie Bénédicte 0000-0001-5121-1260 871849 11 10.3847/1538-4357/acf12b 0004-637X https://iopscience.iop.org/article/10.3847/1538-4357/acf12b Deep Very Large Telescope/MUSE optical integral field spectroscopy has recently revealed an abundant population of ultra-faint galaxies ( M UV ≈ −15; 0.01 L ⋆ ) at z = 2.9−6.7 due to their strong Ly α emission with no detectable continuum. The implied Ly α equivalent widths can be in excess of 100–200 Å, challenging existing models of normal star formation and indicating extremely young ages, small stellar masses, and a very low amount of metal enrichment. We use JWST/NIRSpec’s microshutter array to follow up 45 of these galaxies (11 hr in G235M/F170LP and 7 hr in G395M/F290LP), as well as 45 lower-equivalent width Ly α emitters. Our spectroscopy covers the range 1.7−5.1 micron in order to target strong optical emission lines: H α , [O iii ], H β , and [N II]. Individual measurements as well as stacks reveal line ratios consistent with a metal-poor nature (2%−40% Z ⊙ , depending on the calibration). The galaxies with the highest equivalent widths of Ly α , in excess of 90 Å, have lower [N II]/H α (1.9 σ ) and [O iii ]/H β (2.2 σ ) ratios than those with lower equivalent widths, implying lower gas-phase metallicities at a combined significance of 2.4 σ . This implies a selection based on Ly α equivalent width is an efficient technique for identifying younger, less chemically enriched systems. Dewey 520 Space Telescope Science Institute JWST-GO-1671 MEC ∣ Fundação para a Ciência e a Tecnologia PTDC/FIS-AST/4862/2020 MEC ∣ Fundação para a Ciência e a Tecnologia UIDB/04434/2020 MEC ∣ Fundação para a Ciência e a Tecnologia UIDP/04434/2020 MEC ∣ Fundação para a Ciência e a Tecnologia 2020.03379.CEECIND Ministry of Education, Culture, Sports, Science and Technology HJH02007 MEXT ∣ Japan Society for the Promotion of Science 20K22358 MEXT ∣ Japan Society for the Promotion of Science 22H01258 MEXT ∣ Japan Society for the Promotion of Science JP19K23462 MEXT ∣ Japan Society for the Promotion of Science JP21H01129 Wisconsin Alumni Research Foundation MSN251397 National Science Foundation Characterizing Low-Mass Galaxies with Spectroscopy Through Cosmic Time 2205519 US Directorate for Mathematical & Physical Sciences French National Research Agency (ANR) Lyman-alpha Intensity Mapping of the High Redshift Intergalactic Medium ANR-20-CE92-0015 L-INTENSE FR 26 Département d'astronomie 12 false The Astrophysical journal 956 1 cc2fd55c-2bba-44c3-bd67-0c15202ca401 Article (Published version) Public Maseda_2023_ApJ_956_11.pdf 2193598 application/pdf CC BY-4.0 0424a059ede96376d6d3e8d552dc3ef86aeed4f1b1b8db83282c711a72814877 openAccess Faculté des sciences / Département d'astronomie

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JWST/NIRSpec Measurements of Extremely Low Metallicities in High Equivalent Width Lyα Emitters	The Astrophysical journal			2023	8	83

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Kusakabe, Haruka