BEACON: JWST NIRCam Pure-parallel Imaging Survey. III. Constraints on the UV LF and the Clustering of z~7-14 Galaxies

Abstract

The James Webb Space Telescope (JWST) has extended the frontier of galaxy detection to redshifts z>11, finding a high abundance of UV-bright sources that challenge theoretical models. However, most current results come from just a few fields, introducing uncertainties due to cosmic variance. Here, we constrain z~7-14 UV luminosity functions (LFs) over ~400 sq. arcmin across 36 independent sightlines from DR2 of BEACON, a JWST pure-parallel NIRCam multi-band imaging survey. We identify 164 7<z<12 galaxy candidates: 150 F090W-, 14 F115W-, and no robust F150W-dropouts. In the 11 pointings overlapping with public JWST spectroscopy, we find no contaminants, indicating a high purity in our sample. Our z~7.5 UV LF agrees with previous bright-end measurements but yields lower number densities at -21 < Muv < -19. At z~10, our measurements are lower than most photometric JWST results but match spectroscopic constraints, consistent with the high purity of our selection. The LFs at z~7.5 and z~10 are consistent with pre-JWST models, while our limits at z>13 do not rule out a possible excess. We measure significant clustering of bright (Muv<-20.5) galaxies at 7<z<10. Fields hosting such sources are approximately three times more likely to be overdense relative to the full survey, implying that UV-bright galaxies preferentially reside in the most massive halos at these redshifts. Comparing with semi-numerical simulations, we estimate that Muv < -20.5 galaxies inhabit halos ~0.8 dex less massive at z~11 than at z~8, consistent with a shift to higher star formation rates. However, their observed clustering exceeds predictions from pre-JWST luminosity-halo mass relations, suggesting these sources reside in more massive halos than previously modelled and/or multiple halo occupation.

33 pages, 11 figures, accepted to ApJ