Internal Structure, Not Environment, Shapes Metallicity Gradients in Low-Mass Galaxies from MaNGA
Abstract
Dwarf and low-mass galaxies are highly sensitive to stellar feedback and gas flows, yet their spatially resolved gas-phase metallicity remains poorly characterised. We measure radial gas-phase metallicity gradients for 382 star-forming low-mass galaxies from MaNGA DR17, spanning 7.2 ≤ log(M⋆/M⊙) ≤ 9.1 and z ≤ 0.05. Spectra are stacked in elliptical radial bins and metallicity is derived from the N2 index. After removing the primary dependence on local stellar mass surface density, we define a residual metallicity ΔZ to isolate secondary dependencies. Gradients are flat on average (median slope −0.007\,dex\,Re−1). The residual gradients correlate most strongly with light concentration (r = 0.304, r2 = 0.092, p < 0.001) and gas velocity dispersion (r = 0.204, p < 0.001), though both account for at most 9 per cent of the variance. Large-scale environment shows no significant correlation. The concentration result is robust to measurement uncertainties and persists with a stricter resolution cut, suggesting internal structural properties shape the radial metal distribution in low-mass galaxies.
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BibTeX
@misc{dasgupta2026internal,
title = {{Internal Structure, Not Environment, Shapes Metallicity Gradients in Low-Mass Galaxies from MaNGA}},
author = {Anuroop Dasgupta and Namrata Roy and Saumyadip Samui and Ritaban Chatterjee and Fuyan Bian},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.39689},
eprint = {2609.39689},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.39689},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Internal Structure, Not Environment, Shapes Metallicity Gradients in Low-Mass Galaxies from MaNGA
AU - Anuroop Dasgupta
AU - Namrata Roy
AU - Saumyadip Samui
AU - Ritaban Chatterjee
AU - Fuyan Bian
PY - 2026
DA - 2026/09/30
PB - arXiv
DO - 10.48550/arxiv.2609.39689
UR - https://arxiv.org/abs/2609.39689
AB - Dwarf and low-mass galaxies are highly sensitive to stellar feedback and gas flows, yet their spatially resolved gas-phase metallicity remains poorly characterised. We measure radial gas-phase metallicity gradients for 382 star-forming low-mass galaxies from MaNGA DR17, spanning 7.2 ≤ log(M_⋆/M_⊙) ≤ 9.1 and z ≤ 0.05. Spectra are stacked in elliptical radial bins and metallicity is derived from the N2 index. After removing the primary dependence on local stellar mass surface density, we define a residual metallicity ΔZ to isolate secondary dependencies. Gradients are flat on average (median slope −0.007\,dex\,R_e^−1). The residual gradients correlate most strongly with light concentration (r = 0.304, r^2 = 0.092, p < 0.001) and gas velocity dispersion (r = 0.204, p < 0.001), though both account for at most 9 per cent of the variance. Large-scale environment shows no significant correlation. The concentration result is robust to measurement uncertainties and persists with a stricter resolution cut, suggesting internal structural properties shape the radial metal distribution in low-mass galaxies.
ER -