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arXiv · 2510.11326

MSA-3D: Uncovering Weak AGNs and Resolved Outflows in Disguise in $z\sim1$ Star-Forming Galaxies

Namrata Roy·Alaina Henry·Tucker Jones·Ivana Barisic·Ryan L. Sanders·Kevin Bundy·Matthew A. Malkan·Themiya Nanayakkara·Karl Glazebrook·Timothy Heckman·Juan M. Espejo Salcedo·Xin Wang·Danail Obreschkow·Tommaso Treu
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Abstract

We present spatially resolved rest-optical spectroscopy of 38 star-forming galaxies at 0.5 < z < 1.7 from the JWST/NIRSpec MSA-3D survey, which uses slit-stepping to build IFU-like datacubes at 0.1'' resolution. We map emission-line morphology, excitation, and kinematics of the warm ionized gas using [N II]/H$\alpha$, [S II]/H$\alpha$, and [O III]/H$\beta$. Relative to z$\sim$0 galaxies at fixed stellar mass, our sources show systematically lower [N II]/H$\alpha$ and [S II]/H$\alpha$ and elevated [O III]/H$\beta$, consistent with harder radiation fields and lower metallicities. Radially, [O III]/H$\beta$ profiles are typically flat or mildly positive, whereas [N II]/H$\alpha$ also remains flat or declines outward, mirroring metallicity trends. On kpc scales, we find a strong positive correlation between [N II]/H$\alpha$ and velocity dispersion ($\sigma$), linking local excitation to turbulent or shock-driven kinematics. Six galaxies ($\sim$ 16% of the sample) host spatially localized regions with elevated [N II]/H$\alpha$, high EW(H$\alpha$), and V_RMS = $\sqrt{V^2 + \sigma^2} > 200$ km/s, indicative of weak AGN activity, shocks, or outflows. For these candidates we infer modest warm-ionized outflow rates of 1-4 Msun/yr and kinetic powers $\sim$ 0.1-1% of the AGN bolometric luminosity (from central [O III] or H$\alpha$). These values place our sample at the low-energy tail of known AGN-driven outflows yet in continuity with $\dot{M_{out}}-L_{AGN}$ scaling relations across 0 < z < 6. A completeness assessment shows MSA-3D is sensitive to AGN with $L_{AGN} \geq 10^{43}$ erg/s, underscoring both the promise and current limitations of detecting weak AGN activity in distant galaxies with resolved spectroscopy.

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Namrata Roy, Alaina Henry, Tucker Jones, Ivana Barisic, Ryan L. Sanders, Kevin Bundy, Matthew A. Malkan, Themiya Nanayakkara, Karl Glazebrook, Timothy Heckman, Juan M. Espejo Salcedo, Xin Wang, Danail Obreschkow, Tommaso Treu. 2025-10-13. MSA-3D: Uncovering Weak AGNs and Resolved Outflows in Disguise in $z\sim1$ Star-Forming Galaxies. https://arxiv.org/abs/2510.11326

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