학술논문
Spectroscopic Confirmation of CEERS NIRCam-selected Galaxies at z ≃ 8–10
Document Type
article
Author
Pablo Arrabal Haro; Mark Dickinson; Steven L. Finkelstein; Seiji Fujimoto; Vital Fernández; Jeyhan S. Kartaltepe; Intae Jung; Justin W. Cole; Denis Burgarella; Katherine Chworowsky; Taylor A. Hutchison; Alexa M. Morales; Casey Papovich; Raymond C. Simons; Ricardo O. Amorín; Bren E. Backhaus; Micaela B. Bagley; Laura Bisigello; Antonello Calabrò; Marco Castellano; Nikko J. Cleri; Romeel Davé; Avishai Dekel; Henry C. Ferguson; Adriano Fontana; Eric Gawiser; Mauro Giavalisco; Santosh Harish; Nimish P. Hathi; Michaela Hirschmann; Benne W. Holwerda; Marc Huertas-Company; Anton M. Koekemoer; Rebecca L. Larson; Ray A. Lucas; Bahram Mobasher; Pablo G. Pérez-González; Nor Pirzkal; Caitlin Rose; Paola Santini; Jonathan R. Trump; Alexander de la Vega; Xin Wang; Benjamin J. Weiner; Stephen M. Wilkins; Guang Yang; L. Y. Aaron Yung; Jorge A. Zavala
Source
The Astrophysical Journal Letters, Vol 951, Iss 1, p L22 (2023)
Subject
Language
English
ISSN
2041-8213
2041-8205
2041-8205
Abstract
We present JWST/NIRSpec prism spectroscopy of seven galaxies selected from Cosmic Evolution Early Release Science (CEERS) survey NIRCam imaging with photometric redshifts z _phot > 8. We measure emission line redshifts of z = 7.65 and 8.64 for two galaxies. For two other sources without securely detected emission lines we measure $z={9.77}_{-0.29}^{+0.37}$ and ${10.01}_{-0.19}^{+0.14}$ by fitting model spectral templates to the prism data, from which we detect continuum breaks consistent with Ly α opacity from a mostly neutral intergalactic medium. The presence of strong breaks and the absence of strong emission lines give high confidence that these two galaxies have redshifts z > 9.6, but the redshift values derived from the breaks alone have large uncertainties given the low spectral resolution and relatively low S/N of the CEERS NIRSpec prism data. The two z ∼ 10 sources observed are relatively luminous ( M _UV < −20), with blue continua (−2.3 ≲ β ≲ −1.9) and low dust attenuation ( ${A}_{V}\simeq {0.15}_{-0.1}^{+0.3}$ ); and at least one of them has a high stellar mass for a galaxy at that redshift ( $\mathrm{log}({M}_{\star }/{M}_{\odot })\simeq {9.3}_{-0.3}^{+0.2}$ ). Considered together with spectroscopic observations of other CEERS NIRCam-selected high- z galaxy candidates in the literature, we find a high rate of redshift confirmation and low rate of confirmed interlopers (8%). Ten out of 35 z > 8 candidates with CEERS NIRSpec spectroscopy do not have secure redshifts, but the absence of emission lines in their spectra is consistent with redshifts z > 9.6. We find that z > 8 photometric redshifts are generally in agreement (within their uncertainties) with the spectroscopic values, but also that the photometric redshifts tend to be slightly overestimated (〈Δ z 〉 = 0.45 ± 0.11), suggesting that current templates do not fully describe the spectra of very-high- z sources. Overall, the spectroscopy solidifies photometric redshift evidence for a high spatial density of bright galaxies at z > 8 compared to theoretical model predictions, and further disfavors an accelerated decline in the integrated UV luminosity density at z > 8.