Templates for Fitting Photometry of Ultra-high-redshift Galaxies

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Recent data from the James Webb Space Telescope allow a first glimpse of galaxies at z ≳ 11. The most successful tool for identifying ultra-high-redshift candidates and inferring their properties is photometric template fitting. However, current methods rely on templates derived from much lower-redshift conditions, including stellar populations older than the age of the Universe at z > 12, a stellar initial mass function that is physically disallowed at z > 6, and weaker emission lines than currently observed at z > 7.5. Here, two sets of synthetic templates, optimized for the expected astrophysics of galaxies at 8 < z < 12 and z > 12, are developed and used to fit three galaxies at z > 12 from the SMACS0723 field. Using these improved templates, quantitative estimates are produced of the bias in inferred properties from JWST observations at z > 8 due to these effects. The best-fit redshifts are similar to those found with previous template sets, but the inferred stellar masses drop by as much as 1-1.6 dex, such that stellar masses are no longer seemingly inconsistent with ΛCDM. The two new template sets are released in formats compatible with EAZY and LePhare.

Original languageEnglish
Article numberL40
JournalAstrophysical Journal Letters
Volume951
Issue number2
Number of pages7
ISSN2041-8205
DOIs
Publication statusPublished - 12 Jul 2023

Bibliographical note

Publisher Copyright:
© 2023. The Author(s). Published by the American Astronomical Society.

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