Templates for Fitting Photometry of Ultra-High-Redshift Galaxies

Understand

Recent data from the James Webb Space Telescope allow a first glimpse of galaxies at $z \gtrsim 11$.

• 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 which 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.