Performance of photometric template fitting for ultra-high-redshift galaxies

¹ Cosmic Dawn Center (DAWN), Denmark
² Niels Bohr Institute, University of Copenhagen, Jagtvej 128, 2200 Copenhagen N, Denmark
³ Department of Physics and Astronomy, University of Missouri, Columbia, MO, USA
⁴ DARK Cosmology Center, University of Copenhagen, Jagtvej 128, 2200 Copenhagen N, Denmark
⁵ California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125, USA

^★ Corresponding author.

Received: 1 December 2024
Accepted: 17 March 2025

Abstract

The James Webb Space Telescope (JWST) has enabled the discovery of a significant population of galaxies at z > 10. Our understanding of the astrophysical properties of these galaxies relies on fitting templates developed using models predicting the differences between these first galaxies and lower-redshift counterparts. In this work, tests are performed on several of these high-redshift template sets in order to determine how successful they are at predicting both photometric redshifts and full spectral energy distributions (SEDs). Our work shows that the best templates for photometric redshift estimation differ from the best templates for predicting the full SED. Overall, some templates perform adequately at photometric redshift estimation, while all are generally poor predictors of the full SED. A few objects in particular are poorly fit by all the template sets tested. We conclude that although photometric redshifts can be reliable when given a high enough observational depth and adequate filters, models are not yet able to produce robust astrophysical properties for these ultra-high-redshift galaxies.