CEERS Spectroscopic Confirmation of NIRCam-selected z ≳ 8 Galaxy Candidates with JWST/NIRSpec: Initial Characterization of Their Properties
Year: 2023
Type: article
Abstract: We present JWST NIRSpec spectroscopy for 11 galaxy candidates with photometric redshifts of z ≃ 9 − 13 and M UV ∈ [ −21, −18] newly identified in NIRCam images in the Cosmic Evolution Early Release Science Survey. We confirm emission line redshifts for 7 galaxies at z = 7.762–8.998 using spectra at ∼1–5 μ m either with the NIRSpec prism or its three medium-resolution ( R ∼ 1000) gratings. For z ≃ 9 photometric candidates, we achieve a high confirmation rate of ≃90%, which validates the classical dropout selection from NIRCam photometry. No robust emission lines are identified in three galaxy candidates at z > 10, where the strong [O iii ] and H β lines would be redshifted beyond the wavelength range observed by NIRSpec, and the Ly α continuum break is not detected with the sensitivity of the current data. Compared with Hubble Space Telescope-selected bright galaxies ( M UV ≃ −22) that are similarly spectroscopically confirmed at z ≃ 8 − 9, these NIRCam-selected galaxies are characterized by lower star formation rates (SFRs; SFR ≃ 4 M ⊙ yr −1 ) and lower stellar masses (≃10 8 M ⊙ ), but with higher specific SFR (≃40 Gyr −1 ), higher [O iii ]+H β equivalent widths (≃1100 Å), and elevated production efficiency of ionizing photons ( log ( ξ ion / Hz erg − 1 ) ≃ 25.8 ) induced by young stellar populations (<10 Myr) accounting for ≃20% of the galaxy mass, highlighting the key contribution of faint galaxies to cosmic reionization. Taking advantage of the homogeneous selection and sensitivity, we also investigate metallicity and ISM conditions with empirical calibrations using the [O iii ] 5008 /H β ratio. We find that galaxies at z ≃ 8 − 9 have higher SFRs and lower metallicities than galaxies at similar stellar masses at z ≃ 2 − 6, which is generally consistent with the current galaxy formation and evolution models.
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, Andrea Grazian, Lisa J. Kewley, Dale D. Kocevski, Jennifer M. Lotz, Laura Pentericci, Swara Ravindranath, Rachel S. Somerville, Stephen M. Wilkins, Ricardo O. Amorín, Bren E. Backhaus, Antonello Calabrò, Caitlin M. Casey, M. C. Cooper, Vital Fernández, Maximilien Franco, Mauro Giavalisco, Nimish P. Hathi, Santosh Harish, Taylor A. Hutchison, Kartheik G. Iyer, Intae Jung, Ray A. Lucas, Jorge A. Zavala
Institutions: The University of Texas at Austin, NSF NOIRLab, Rochester Institute of Technology, Centre National de la Recherche Scientifique, Aix-Marseille Université, University of Arizona, National Astronomical Observatory of Japan, Trieste Astronomical Observatory, École Polytechnique Fédérale de Lausanne, University of Connecticut, University of Sussex, University of Malta, Goddard Space Flight Center, Space Telescope Science Institute, Texas A&M University, Astronomical Observatory of Rome, National Institute for Astrophysics, Osservatorio Astronomico di Padova, Center for Astrophysics Harvard & Smithsonian, Colby College, International Gemini Observatory, Flatiron Institute, University of La Serena, University of California, Irvine, University of Massachusetts Amherst, University of Toronto
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,400
OpenAlex ID: W4379518351