# Spectral Templates Optimal for Selecting Galaxies at z > 8 with JWST

**Authors:** Rebecca L. Larson, Taylor A. Hutchison, Micaela Bagley, Steven L. Finkelstein, L. Y. Aaron Yung, Rachel S. Somerville, Michaela Hirschmann, Gabriel Brammer, Benne W. Holwerda, Casey Papovich, Alexa M. Morales, Stephen M. Wilkins  
**arXiv:** [2211.10035](https://arxiv.org/abs/2211.10035)  
**Date:** 2022-11-18  
**Summary page:** https://www.summarizepaper.com/en/paper/2211.10035v1/

## Key points

- Selection of high-redshift galaxies, especially those at z > 8, is crucial for understanding the early universe.
- Determining redshifts of these galaxies through photometric data can be challenging.
- Rest-frame ultraviolet (UV) colors of z > 8 galaxies are often bluer than expected from model templates.
- Researchers have developed spectral templates that better match the predicted rest-UV colors of z > 8 galaxies.
- The effectiveness of these templates was tested using a mock catalog mimicking the Cosmic Evolution Early Release Science Survey (CEERS).
- Incorporating these new templates into analysis with EAZY software enhances redshift recovery accuracy for galaxies at 8 < z < 10.
- This work provides insights for astronomers using the James Webb Space Telescope (JWST) to study high-redshift galaxies.

## Summary

The selection of high-redshift galaxies, particularly those at z > 8, is crucial for understanding the early universe. Accurately determining the redshifts of these galaxies solely through photometric data can be challenging, as spectral energy distribution (SED) fitting relies on comparing observed photometry to model templates. However, the rest-frame ultraviolet (UV) colors of z > 8 galaxies are often bluer than what is typically expected from these templates, leading to potential errors in photometric redshift estimation. To address this issue, a team of researchers has developed a set of spectral templates that better match the predicted rest-UV colors of z > 8 galaxies. Combining BPASS and Cloudy models, they tested their effectiveness using a mock catalog that mimics the expected field depths and areas of the Cosmic Evolution Early Release Science Survey (CEERS). This survey is being conducted by the James Webb Space Telescope (JWST) over several extragalactic fields, providing an ideal opportunity for discovering and classifying distant galaxies. By incorporating these new templates into their analysis with EAZY software, they were able to enhance the accuracy of redshift recovery for galaxies at 8 < z < 10. This work provides important insights for astronomers entering this new era of astronomy with JWST and demonstrates how improved spectral templates can address challenges associated with estimating accurate redshifts for high-redshift galaxies using photometric data alone.