BEACON: JWST NIRCam Pure-parallel Imaging Survey. II. Physical Properties of $z=7-14$ Galaxies

TL;DR

This study analyzes the physical properties of 161 high-redshift galaxy candidates at z=7-14 from JWST NIRCam imaging, revealing a remarkably bright galaxy at z=13.7 and exploring environmental effects on galaxy evolution.

Contribution

First comprehensive analysis of physical properties of z=7-14 galaxies from JWST pure-parallel imaging, including the brightest galaxy candidate at z>12 and environmental assessments.

Findings

Identification of a bright galaxy at z=13.7 with unique properties.

No significant environmental dependence on galaxy properties at z>7.

Future larger samples needed to confirm environmental trends.

Abstract

We present photometric properties of 161 galaxy candidates at $z=7-14$ selected from the second data release (DR2) of BEACON, a JWST Cycle 2 pure-parallel NIRCam imaging program. Carefully selected from 36 independent pointings (corresponding to $\sim350$\,arcmin$^2$ sky coverage), and hence with reduced cosmic variance, our galaxy candidates provide an unbiased sample for investigating galaxy properties over a wide range of environments. We measure the physical properties, including UV continuum slope ($\beta_{\rm UV}$), stellar mass ($M_*$), star formation rate (SFR), and sizes. Our highest redshift galaxy candidate at $z=13.71\pm0.15$ has a remarkably bright UV luminosity of $M_{\rm UV}=-21.19\pm0.08$, making it the brightest galaxy at $z>12$ if spectroscopically confirmed. With an extremely blue UV slope, compact morphology, and high star formation rate surface density ($\Sigma_{\rm SFR}$), this candidate may have extremely low metallicity, high ionizing photon escape fraction, or contributions from an AGN. Among our multiple independent sightlines, we identify three fields of galaxy number overdensity with $>3\sigma$ significance. The properties of galaxies in various environments do not exhibit significant differences, implying either that accelerated galaxy evolution in overdense regions is not yet widespread at $z>7$, or that the current constraints are limited by sample size. Our simulations indicate that increasing the sample by an order of magnitude would allow such environmental trends to be robustly confirmed or ruled out, underscoring the importance of future pure-parallel observations.