# CEERS Spectroscopic Confirmation of NIRCam-Selected z > 8 Galaxy Candidates with JWST/NIRSpec: Initial Characterization of their Properties

**Authors:** Seiji Fujimoto, Pablo Arrabal Haro, Mark Dickinson, Steven L. Finkelstein, Jeyhan S. Kartaltepe, Rebecca L. Larson, Denis Burgarella, Micaela B. Bagley, Peter Behroozi, Katherine Chworowsky, Michaela Hirschmann, Jonathan R. Trump, Stephen M. Wilkins, L. Y. Aaron Yung, Anton M. Koekemoer, Casey Papovich, Nor Pirzkal, Henry C. Ferguson, Adriano Fontana, Norman A. Grogin  
**arXiv:** [2301.09482](https://arxiv.org/abs/2301.09482)  
**Date:** 2023-01-23  
**Summary page:** https://www.summarizepaper.com/en/paper/2301.09482v1/

## Key points

- Spectroscopic confirmation of 11 galaxy candidates with photometric redshifts of $z\simeq9-13$ and $M_{\rm\,UV} \in[-21,-18]"
- Spectroscopic observations carried out using JWST NIRSpec instrument
- Emission line redshifts successfully confirmed for 7 galaxies in the range of $z=7.762-8.998$
- High confirmation rate of $\simeq$90% for photometric candidates at $z\simeq9$
- No robust emission lines identified in three galaxy candidates at $z>10"
- Comparisons made between NIRCam-selected galaxies and HST-selected bright galaxies ($M_{\rm\,UV}\simeq-22$)
- NIRCam-selected galaxies exhibit lower star formation rates (SFRs) and stellar masses compared to HST-selected galaxies
- NIRCam-selected galaxies have higher [OIII]+H$\beta$ equivalent widths and elevated production efficiency of ionizing photons induced by young stellar populations
- Empirical calibrations based on [OIII]/H$\beta$ ratio used to investigate metallicity and interstellar medium (ISM) conditions
- Higher SFRs and lower metallicities found in high-redshift galaxies compared to lower redshift galaxies
- Observations carried out as part of CEERS program in CANDELS Extended Groth Strip (EGS) field using JWST/NIRCam and JWST/NIRSpec instruments

## Summary

: In this study, the authors present the results of spectroscopic confirmation of 11 galaxy candidates with photometric redshifts of $z\simeq9-13$ and $M_{\rm\,UV} \in[-21,-18]$, which were newly identified in NIRCam images as part of the Cosmic Evolution Early Release Science (CEERS) Survey. The spectroscopic observations were carried out using the JWST NIRSpec instrument, with spectra obtained at wavelengths ranging from $\sim1-5\mu$m using either the NIRSpec prism or its three medium resolution gratings. Out of the 11 galaxy candidates, emission line redshifts were successfully confirmed for 7 galaxies in the range of $z=7.762-8.998$. The high confirmation rate of $\simeq$90% for photometric candidates at $z\simeq9$ validates the classical dropout selection method based on NIRCam photometry. However, no robust emission lines were identified in three galaxy candidates at $z>10$, where the strong [OIII] and H$\beta$ lines would be redshifted beyond the observed wavelength range, and the Lyman-$\alpha$ continuum break was not detected due to current sensitivity limitations. Comparing these NIRCam-selected galaxies with HST-selected bright galaxies ($M_{\rm\,UV}\simeq-22$) that are similarly spectroscopically confirmed at $z\gtrsim8$, it is found that they exhibit lower star formation rates (SFRs) and stellar masses than those selected by HST; however, they have higher [OIII]+H$\beta$ equivalent widths and an elevated production efficiency of ionizing photons induced by young stellar populations. These findings highlight their significant contribution to cosmic reionization. Additionally, empirical calibrations based on [OIII]/H$\beta$ ratio are used to investigate metallicity and interstellar medium (ISM) conditions of these galaxies at $z \sim 8 - 9$. It is found that they have higher SFRs and lower metallicities compared to galaxies at similar stellar masses at lower redshift ($z \sim 2 - 6$), which is generally consistent with current models. The observations were carried out as part of CEERS program in CANDELS Extended Groth Strip (EGS) field using JWST/NIRCam and JWST/NIRSpec instruments; further details will be presented in a forthcoming publication by Finkelstein et al. This study provides valuable insights into properties and characteristics of high-redshift galaxies while supporting current models of galaxy formation and evolution.