MSA-3D: Connecting the Chemical and Kinematic Structures of Galaxies at <i>z</i>  ∼ 1

Abstract We investigate the connection between ionized gas kinematics and gas-phase metallicity gradients in 21 star-forming galaxies at 0.5 &lt; z &lt; 1.7 from the MSA-3D survey, using spatially resolved JWST/NIRSpec slit-stepping observations. Galaxy kinematics are characterized by the ratio of rotational velocity to intrinsic velocity dispersion, v / σ , measured at 1.5 R e , where R e is the effective radius. We find that dynamically hotter disks exhibit systematically flatter metallicity gradients, with a moderate anticorrelation between ∇O/H and v / σ ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>ρ</mml:mi> <mml:mo>=</mml:mo> <mml:mo>−</mml:mo> <mml:mn>0.3</mml:mn> <mml:msubsup> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.15</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.16</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> ). A linear fit yields a slope of ∼0.005 dex per dex in v / σ , weaker than the dependence on stellar mass. Similarly, the N2 gradients show a consistent trend, with <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>ρ</mml:mi> <mml:mo stretchy="false">(</mml:mo> <mml:mi>v</mml:mi> <mml:mo>/</mml:mo> <mml:mi>σ</mml:mi> <mml:mo>,</mml:mo> <mml:mrow> <mml:mo mathvariant="normal">∇</mml:mo> </mml:mrow> <mml:mi mathvariant="normal">N2</mml:mi> <mml:mo stretchy="false">)</mml:mo> <mml:mo>=</mml:mo> <mml:mo>−</mml:mo> <mml:mn>0.2</mml:mn> <mml:msubsup> <mml:mrow> <mml:mn>3</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.08</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.07</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> , indicating that the correlation is robust to the choice of metallicity indicator. A significantly stronger anticorrelation is observed with R e / σ , interpreted as a proxy for the radial mixing timescale (Spearman rank correlation coefficient <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>ρ</mml:mi> <mml:mo>=</mml:mo> <mml:mo>−</mml:mo> <mml:mn>0.4</mml:mn> <mml:msubsup> <mml:mrow> <mml:mn>3</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.13</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.14</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> ), suggesting that cumulative radial mixing more directly regulates chemical stratification. The metallicity gradients in our sample are uniformly shallow, indicating that efficient turbulent mixing in kinematically settled disks regulates the chemical structure of typical star-forming galaxies at z ∼ 1.