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First Census of Gas-phase Metallicity Gradients of Star-forming Galaxies in Overdense Environments at Cosmic Noon

Li, Zihao and Wang, Xin and Cai, Zheng and Shi, Dong Dong and Fan, Xiaohui and Zheng, Xian Zhong and Malkan, Matthew A. and Teplitz, Harry I. and Henry, Alaina L. and Bian, Fuyan and Colbert, James (2022) First Census of Gas-phase Metallicity Gradients of Star-forming Galaxies in Overdense Environments at Cosmic Noon. Astrophysical Journal Letters, 929 (1). Art. No. L8. ISSN 2041-8205. doi:10.3847/2041-8213/ac626f.

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We report the first spatially resolved measurements of gas-phase metallicity radial gradients in star-forming galaxies in overdense environments at z ≳ 2. The spectroscopic data are acquired by the MAMMOTH-Grism survey, a Hubble Space Telescope (HST) cycle 28 medium program. This program is obtaining 45 orbits of WFC3/IR grism spectroscopy in the density peak regions of three massive galaxy protoclusters (BOSS 1244, BOSS 1542, and BOSS 1441) at z = 2–3. Our sample in the BOSS 1244 field consists of 20 galaxies with stellar mass ranging from 10^(9.0) to 10^(10.3) M_⊙, star formation rate (SFR) from 10 to 240 M_⊙ yr⁻¹, and global gas-phase metallicity (12+ log{O/H) from 8.2 to 8.6. At 1σ confidence level, 2/20 galaxies in our sample show positive (inverted) gradients—the relative abundance of oxygen increasing with galactocentric radius, opposite the usual trend. Furthermore, 1/20 shows negative gradients, and 17/20 are consistent with flat gradients. This high fraction of flat/inverted gradients is uncommon in simulations and previous observations conducted in blank fields at similar redshifts. To understand this, we investigate the correlations among various observed properties of our sample galaxies. We find an anticorrelation between metallicity gradient and global metallicity of our galaxies residing in extreme overdensities, and a marked deficiency of metallicity in our massive galaxies as compared to their coeval field counterparts. We conclude that the cold-mode gas accretion plays an active role in shaping the chemical evolution of galaxies in the protocluster environments, diluting their central chemical abundance, and flattening/inverting their metallicity gradients.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Li, Zihao0000-0001-5951-459X
Wang, Xin0000-0002-9373-3865
Cai, Zheng0000-0001-8467-6478
Shi, Dong Dong0000-0002-4314-5686
Fan, Xiaohui0000-0003-3310-0131
Zheng, Xian Zhong0000-0003-3728-9912
Malkan, Matthew A.0000-0001-6919-1237
Teplitz, Harry I.0000-0002-7064-5424
Henry, Alaina L.0000-0002-6586-4446
Bian, Fuyan0000-0002-1620-0897
Colbert, James0000-0001-6482-3020
Additional Information:© 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Received 2022 February 5; revised 2022 March 15; accepted 2022 March 30; published 2022 April 11. We would thank the anomymous referee for the helpful comments that ensures the quality of this paper. Z.L. and Z.C. are supported by the National Key RD Program of China (grant No. 2018YFA0404503), the National Science Foundation of China (grant No. 12073014), and the science research grants from the China Manned Space Project with No. CMS-CSST-2021-A05. This work is supported by NASA through HST grant HST-GO-16276. Software: Emcee (Foreman-Mackey et al. 2013), Grizli (Brammer & Matharu 2021), GALFIT (Peng et al. 2002), VorBin (Cappellari & Copin 2003), Linmix (Kelly 2007).
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
National Key Research and Development Program of China2018YFA0404503
National Science Foundation of China12073014
China Manned Space ProjectCMS-CSST-2021-A05
Subject Keywords:Galaxies; Protoclusters; Chemical abundances; Galaxy formation; Galaxy evolution; High-redshift galaxies
Issue or Number:1
Classification Code:Unified Astronomy Thesaurus concepts: Galaxies (573); Protoclusters (1297); Chemical abundances (224); Galaxy formation (595); Galaxy evolution (594); High-redshift galaxies (734)
Record Number:CaltechAUTHORS:20220608-849521000
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Official Citation:Zihao Li et al 2022 ApJL 929 L8
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:115090
Deposited By: George Porter
Deposited On:08 Jun 2022 22:29
Last Modified:08 Jun 2022 22:29

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