The Grism Lens-amplified Survey from Space (GLASS). X. Sub-kiloparsec Resolution Gas-phase Metallicity Maps at Cosmic Noon behind the Hubble Frontier Fields Cluster MACS1149.6+2223

Journal
Date Issued
2017
Author(s)
Wang, Xin
•
Jones, Tucker A.
•
Treu, Tommaso
•
Morishita, Takahiro
•
Abramson, Louis E.
•
Brammer, Gabriel B.
•
Huang, Kuang-Han
•
Malkan, Matthew A.
•
Schmidt, Kasper B.
•
•
•
Henry, Alaina L.
•
Karman, Wouter
•
Kelly, Patrick L.
•
Mason, Charlotte A.
•
•
•
Sharon, Keren
•
Trenti, Michele
•
DOI
Abstract
We combine deep Hubble Space Telescope grism spectroscopy with a new Bayesian method to derive maps of gas-phase metallicity for 10 star-forming galaxies at high redshift (1.2≲ z≲ 2.3). Exploiting lensing magnification by the foreground cluster MACS1149.6+2223, we reach sub-kiloparsec spatial resolution and push the limit of stellar mass associated with such high-z spatially resolved measurements below {10}8 {M}☉ for the first time. Our maps exhibit diverse morphologies, indicative of various effects such as efficient radial mixing from tidal torques, rapid accretion of low-metallicity gas, and other physical processes that can affect the gas and metallicity distributions in individual galaxies. Based upon an exhaustive sample of all existing sub-kiloparesec resolution metallicity gradient measurements at high z, we find that predictions given by analytical chemical evolution models assuming a relatively extended star-formation profile in the early disk-formation phase can explain the majority of observed metallicity gradients, without involving galactic feedback or radial outflows. We observe a tentative correlation between stellar mass and metallicity gradients, consistent with the “downsizing” galaxy formation picture that more massive galaxies are more evolved into a later phase of disk growth, where they experience more coherent mass assembly at all radii and thus show shallower metallicity gradients. In addition to the spatially resolved analysis, we compile a sample of homogeneously cross-calibrated integrated metallicity measurements spanning three orders of magnitude in stellar mass at z ∼ 1.8. We use this sample to study the mass-metallicity relation (MZR) and find that the slope of the observed MZR can rule out the momentum-driven wind model at a 3σ confidence level.
Volume
837
Issue
1
Start page
89
Uri
Url
Issn Identifier
0004-637X
Ads BibCode
2017ApJ...837...89W
Rights
open.access
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