2024MNRAS.527.5004M

We present a new determination of the evolving galaxy ultraviolet (UV) luminosity function (LF) over the redshift range 9.5 < z < 12.5 based on a wide-area (>250 arcmin²) data set of JWST NIRCam near-infrared imaging assembled from 13 public JWST surveys. Our relatively large-area search allows us to uncover a sample of 61 robust z > 9.5 candidates detected at ≥8σ, and hence place new constraints on the intermediate-to-bright end of the UV LF. When combined with our previous JWST + UltraVISTA results, this allows us to measure the form of the LF over a luminosity range corresponding to four magnitudes (M₁₅₀₀). At these early times we find that the galaxy UV LF is best described by a double power-law function, consistent with results obtained from recent ground-based and early JWST studies at similar redshifts. Our measurements provide further evidence for a relative lack of evolution at the bright-end of the UV LF at z = 9-11, but do favour a steep faint-end slope (α ≤ -2). The luminosity-weighted integral of our evolving UV LF provides further evidence for a gradual smooth (exponential) decline in co-moving star-formation rate density (ρ_SFR) at least out to z ≃ 12, with our determination of ρ_SFR(z = 11) lying significantly above the predictions of many theoretical models of galaxy evolution.