Sparse X-ray Counterparts to High-Redshift JWST Galaxies Under Strict Geometric Constraints

We present a disciplined cross-matching analysis between JWST deep-field galaxy catalogsand the Chandra Source Catalog 2.1 (CSC 2.1), designed to identify physically plausiblehigh-redshift X-ray counterparts under fixed geometric constraints. JWST serves as theconstraining dataset, defining an initial parent sample of 80 high-redshift galaxies across theEGS and UDS fields; Chandra data are queried only at these JWST source positions and actstrictly as a secondary augmentation. Enforcing a non-inflated matching radius of 1.0 arcsecand deterministic confidence tiers, we find only three sources with credible CSC associations.All three reside at redshifts z ≈ 3.6–5.2, are isolated in JWST source space, and exhibit X-rayluminosities firmly in the AGN regime. The low match rate is treated as an empirical outcomerather than a limitation. This work establishes a conservative baseline for JWST–Chandracross-association and surfaces a small set of physically interpretable systems suitable fordeeper follow-up.