JWST CAPERS: Spectroscopic evaluation of very high redshift galaxy candidates

@misc{donnan2026jwst,
  title = {{JWST CAPERS: Spectroscopic evaluation of very high redshift galaxy candidates}},
  author = {Callum T. Donnan and Mark Dickinson and Lorenzo Napolitano and Pablo Arrabal Haro and Anthony J. Taylor and Hollis B. Akins and Ryan Begley and Davide Bevacqua and Adam C. Carnall and Marco Castellano and Fergus Cullen and James S. Dunlop and Steven L. Finkelstein and Carter Flayhart and Mauro Giavalisco and Michaela Hirschmann and Ray A. Lucas and Derek J. McLeod and Ross J. McLure and Casey Papovich and Laura Pentericci and Borja Pérez-Díaz and Thomas M. Stanton and L. Y. Aaron Yung},
  howpublished = {arXiv},
  year = {2026},
  month = oct,
  doi = {10.48550/arxiv.2610.12322},
  eprint = {2610.12322},
  archivePrefix = {arXiv},
  url = {https://arxiv.org/abs/2610.12322},
  note = {CC BY 4.0},
}

TY  - UNPB
TI  - JWST CAPERS: Spectroscopic evaluation of very high redshift galaxy candidates
AU  - Callum T. Donnan
AU  - Mark Dickinson
AU  - Lorenzo Napolitano
AU  - Pablo Arrabal Haro
AU  - Anthony J. Taylor
AU  - Hollis B. Akins
AU  - Ryan Begley
AU  - Davide Bevacqua
AU  - Adam C. Carnall
AU  - Marco Castellano
AU  - Fergus Cullen
AU  - James S. Dunlop
AU  - Steven L. Finkelstein
AU  - Carter Flayhart
AU  - Mauro Giavalisco
AU  - Michaela Hirschmann
AU  - Ray A. Lucas
AU  - Derek J. McLeod
AU  - Ross J. McLure
AU  - Casey Papovich
AU  - Laura Pentericci
AU  - Borja Pérez-Díaz
AU  - Thomas M. Stanton
AU  - L. Y. Aaron Yung
PY  - 2026
DA  - 2026/10/08
PB  - arXiv
DO  - 10.48550/arxiv.2610.12322
UR  - https://arxiv.org/abs/2610.12322
AB  - JWST/NIRCam imaging has enabled efficient selection of a large number of galaxy candidates at very high redshifts. Accurate and robust selection is crucial for statistical analyses, such as measurement of the ultraviolet luminosity function (UV LF). A variety of selection methods and criteria have been proposed in the literature. We evaluate the selection methodology of galaxy candidates at z≥8.5 using 183 candidates with secure spectroscopic redshifts obtained from the CAPERS JWST/NIRSpec PRISM program. The success of high-z confirmation is strongly correlated with the photometric signal-to-noise ratio (SNR) in the detection filter, the strength of the Lyman-α break, and the Δχ^2 between the best-fitting low-redshift and high-redshift spectral energy distribution model. However, the most efficient selection method is the use of a UV LF prior on the inferred p(z) of a source, raising the success rate from ≃ 35% to ≃ 77% while achieving greater completeness than conservative SNR and Δχ^2 cuts. Out of the 183 candidates we spectroscopically confirm 48 sources at z≥8.5 via detections of emission lines and/or the Lyman-α break (particularly important for those with no emission line detection). We report the highest-redshift source in CAPERS as UDS-111893 at z_spec=12.98, with no sources confirmed at z>13. This work provides spectroscopic quantification of JWST/NIRCam photometric selection at z≥8.5, and demonstrates the effectiveness of a UV LF prior for high-redshift photometric selection.
ER  -