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  • An Indication of Gas Inflow in Clumpy Star-forming Galaxies near z  ∼ 1: Lower Gas-phase Metallicities in Clumpy Galaxies Compared to Nonclumpy Galaxies

This content will become publicly available on January 14, 2026

Title: An Indication of Gas Inflow in Clumpy Star-forming Galaxies near z  ∼ 1: Lower Gas-phase Metallicities in Clumpy Galaxies Compared to Nonclumpy Galaxies
Abstract Despite the ubiquity of clumpy star-forming galaxies at high-redshift, the origin of clumps are still largely unconstrained due to the limited observations that can validate the mechanisms for clump formation. We postulate that if clumps form due to the accretion of metal-poor gas that leads to violent disk instability, clumpy galaxies should have lower gas-phase metallicities compared to nonclumpy galaxies. In this work, we obtain the near-infrared spectrum for 42 clumpy and nonclumpy star-forming galaxies of similar masses, star formation rates, and colors atz ≈ 0.7 using the Gemini Near-Infrared Spectrograph (GNIRS) and infer their gas-phase metallicity from the [Nii]λ6584 and Hαline ratio. We find that clumpy galaxies have lower metallicities compared to nonclumpy galaxies, with an offset in the weighted average metallicity of 0.07 ± 0.02 dex. We also find an offset of 0.06 ± 0.02 dex between clumpy and nonclumpy galaxies in a comparable sample of 23 star-forming galaxies atz ≈ 1.5 using existing data from the FMOS-COSMOS survey. Similarly, lower [Nii]λ6584/Hαratios are typically found in galaxies that have more of their UVrestluminosity originating from clumps, suggesting that clumpier galaxies are more metal-poor. We also derive the intrinsic velocity dispersion and line-of-sight rotational velocity for galaxies from the GNIRS sample. The majority of galaxies haveσ0/vc ≈ 0.2, with no significant difference between clumpy and nonclumpy galaxies. Our result indicates that clump formation may be related to the inflow of metal-poor gas; however, the process that forms them does not necessarily require significant, long-term kinematic instability in the disk.  more » « less
Award ID(s):
2347348
PAR ID:
10638753
Author(s) / Creator(s):
; ; ; ; ; ; ;
Publisher / Repository:
ApJ
Date Published:
Journal Name:
The Astrophysical Journal
Volume:
979
Issue:
1
ISSN:
0004-637X
Page Range / eLocation ID:
14
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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