2026ApJ..1000..151C

The presence (and nature) of variations in the stellar initial mass function (IMF) at substantially subsolar masses and metallicities (m < 0.5M_⊙ and [M/H] ≲ -1, respectively) remains poorly constrained. Predictions from simulations vary widely, while observationally, resolved star studies of ultrafaint dwarf (UFD) galaxies suffer from small sample sizes and background galaxy contamination due to low projected stellar densities. As an alternative metal-poor target, we measure the IMF from resolved stars toward a carefully selected field in the Small Magellanic Cloud, leveraging a plethora of independent constraints on the target field stellar population including distributions of distance, age, and metallicity. We resolve >15,000 stars down to 0.16M_⊙ within a single pointing of NIRCam on board JWST, using an observing strategy that minimizes contamination from point-source-like background galaxies. We explore three different functional forms of the IMF, forward modeling observed color-magnitude diagrams and luminosity functions. We find a best-fit single power law IMF slope of α = -1.61${}_{-0.03}^{+0.03}$, consistent with UFDs probed down to similar limiting masses. Fitting a broken power-law IMF, we find low- and high-mass slopes of α₁ = -1.44${}_{-0.04}^{+0.04}$ and α₂ = -2.17${}_{-0.11}^{+0.11}$, respectively, consistent with solar neighborhood values. Assuming a lognormal IMF, we find a characteristic mass and lognormal width of m_c = $0.1{2}_{-0.03}^{+0.03}{M}_{\odot }$ and σ = 0.61${}_{-0.06}^{+0.07}$M_⊙, respectively, allowing for characteristic masses lower than local values as seen in some simulations as well as low-metallicity Galactic clusters. Lastly, we quantify the impact of assumptions required in our analysis and discuss potential future improvements.