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arXiv · 2512.00730

A source-plane reassessment of the z=6--8 ultraviolet luminosity function behind Abell 2744: no requirement for additional faint-end curvature

Xuheng Ma
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Abstract

We reassess the rest-frame ultraviolet luminosity function (UVLF) at $6\leq z<8$ behind Abell~2744 using public UNCOVER imaging, catalog photometry, and lens products. Observed sources use the released D032 aperture-to-total-corrected photometry; artificial sources use 0.32-arcsec forced apertures with profile- and band-specific corrections to the same total-flux scale. The joint detection and seven-band selection response is calibrated with 1380 artificial sources inside a common $33.36\,\mathrm{arcmin}^{2}$ footprint. Rest-frame $M_{1500}$ is derived from EAZY spectral-energy-distribution fits at eight conditional-redshift-posterior nodes, and the same definition is used to recompute branch-aware source-plane effective volumes. Synthetic F814W flux from the fitted SED and intergalactic absorption is propagated through EAZY and the selector at each volume node. The final sample contains 161 registry-de-duplicated physical sources; 111 and 36 lie in the reliable B6 ($6\leq z<7$) and B7 ($7\leq z<8$) fitting ranges. Bin-integrated Poisson fits give curved-minus-Schechter $Δ\mathrm{AIC}=+4.00$ and $+2.85$, and $Δ\mathrm{BIC}=+5.13$ and $+3.82$, respectively. A response-recalibrated stricter posterior subset and a catalog-level aperture-correction bridge do not reverse the ranking. Thus the calibrated data do not require additional faint-end curvature beyond an unrestricted Schechter function; they do not establish that a turnover is absent at fainter luminosities or in the cosmic-mean UVLF.

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Xuheng Ma. 2026-08-29. A source-plane reassessment of the z=6--8 ultraviolet luminosity function behind Abell 2744: no requirement for additional faint-end curvature. https://arxiv.org/abs/2512.00730

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