The Astrophysical Journal (Jan 2024)
Characterizing the Average Interstellar Medium Conditions of Galaxies at z ∼ 5.6–9 with Ultraviolet and Optical Nebular Lines
- Weida Hu,
- Casey Papovich,
- Mark Dickinson,
- Robert Kennicutt,
- Lu Shen,
- Ricardo O. Amorín,
- Pablo Arrabal Haro,
- Micaela B. Bagley,
- Rachana Bhatawdekar,
- Nikko J. Cleri,
- Justin W. Cole,
- Avishai Dekel,
- Alexander de la Vega,
- Steven L. Finkelstein,
- Norman A. Grogin,
- Nimish P. Hathi,
- Michaela Hirschmann,
- Benne W. Holwerda,
- Taylor A. Hutchison,
- Intae Jung,
- Anton M. Koekemoer,
- Jeyhan S. Kartaltepe,
- Ray A. Lucas,
- Mario Llerena,
- S. Mascia,
- Bahram Mobasher,
- L. Napolitano,
- Jeffrey A. Newman,
- Laura Pentericci,
- Pablo G. Pérez-González,
- Jonathan R. Trump,
- Stephen M. Wilkins,
- L. Y. Aaron Yung
Affiliations
- Weida Hu
- ORCiD
- Department of Physics and Astronomy, Texas A&M University , College Station, TX 77843-4242, USA ; [email protected]; George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A&M University , College Station, TX 77843-4242, USA
- Casey Papovich
- ORCiD
- Department of Physics and Astronomy, Texas A&M University , College Station, TX 77843-4242, USA ; [email protected]; George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A&M University , College Station, TX 77843-4242, USA
- Mark Dickinson
- ORCiD
- NSF’s National Optical-Infrared Astronomy Research Laboratory , 950 N. Cherry Ave., Tucson, AZ 85719, USA
- Robert Kennicutt
- ORCiD
- Department of Physics and Astronomy, Texas A&M University , College Station, TX 77843-4242, USA ; [email protected]; George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A&M University , College Station, TX 77843-4242, USA; Department of Astronomy and Steward Observatory, University of Arizona , Tucson, AZ 85721, USA
- Lu Shen
- ORCiD
- Department of Physics and Astronomy, Texas A&M University , College Station, TX 77843-4242, USA ; [email protected]; George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A&M University , College Station, TX 77843-4242, USA
- Ricardo O. Amorín
- ORCiD
- ARAID Foundation. Centro de Estudios de Física del Cosmos de Aragón (CEFCA) , Unidad Asociada al CSIC, Plaza San Juan 1, E–44001 Teruel, Spain; Departamento de Astronomía, Universidad de La Serena , Av. Juan Cisternas 1200 Norte, La Serena 1720236, Chile
- Pablo Arrabal Haro
- ORCiD
- NSF’s National Optical-Infrared Astronomy Research Laboratory , 950 N. Cherry Ave., Tucson, AZ 85719, USA
- Micaela B. Bagley
- ORCiD
- Department of Astronomy, The University of Texas at Austin , Austin, TX 78712, USA
- Rachana Bhatawdekar
- ORCiD
- European Space Agency (ESA), European Space Astronomy Centre (ESAC) , Camino Bajo del Castillo s/n, 28692 Villanueva de la Cañada, Madrid, Spain
- Nikko J. Cleri
- ORCiD
- Department of Physics and Astronomy, Texas A&M University , College Station, TX 77843-4242, USA ; [email protected]; George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A&M University , College Station, TX 77843-4242, USA
- Justin W. Cole
- ORCiD
- Department of Physics and Astronomy, Texas A&M University , College Station, TX 77843-4242, USA ; [email protected]; George P. and Cynthia Woods Mitchell Institute for Fundamental Physics and Astronomy, Texas A&M University , College Station, TX 77843-4242, USA
- Avishai Dekel
- ORCiD
- Racah Institute of Physics, The Hebrew University of Jerusalem , Jerusalem 91904, Israel
- Alexander de la Vega
- ORCiD
- Department of Physics and Astronomy, University of California , 900 University Ave, Riverside, CA 92521, USA
- Steven L. Finkelstein
- ORCiD
- Department of Astronomy, The University of Texas at Austin , Austin, TX 78712, USA
- Norman A. Grogin
- ORCiD
- Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA
- Nimish P. Hathi
- ORCiD
- Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA
- Michaela Hirschmann
- ORCiD
- Institute of Physics , Laboratory of Galaxy Evolution, Ecole Polytechnique Fédérale de Lausanne (EPFL), Observatoire de Sauverny, 1290 Versoix, Switzerland
- Benne W. Holwerda
- ORCiD
- Physics & Astronomy Department, University of Louisville , 40292 KY, Louisville, USA
- Taylor A. Hutchison
- ORCiD
- Astrophysics Science Division, NASA Goddard Space Flight Center , 8800 Greenbelt Rd, Greenbelt, MD 20771, USA
- Intae Jung
- ORCiD
- Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA
- Anton M. Koekemoer
- ORCiD
- Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA
- Jeyhan S. Kartaltepe
- ORCiD
- Laboratory for Multiwavelength Astrophysics, School of Physics and Astronomy, Rochester Institute of Technology , 84 Lomb Memorial Drive, Rochester, NY 14623, USA
- Ray A. Lucas
- ORCiD
- Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA
- Mario Llerena
- ORCiD
- INAF—Osservatorio Astronomico di Roma , via di Frascati 33, 00078 Monte Porzio Catone, Italy
- S. Mascia
- ORCiD
- INAF—Osservatorio Astronomico di Roma , via di Frascati 33, 00078 Monte Porzio Catone, Italy; Dipartimento di Fisica, Università di Roma Tor Vergata , Via della Ricerca Scientifica, 1, 00133, Roma, Italy
- Bahram Mobasher
- ORCiD
- Department of Physics and Astronomy, University of California , 900 University Ave, Riverside, CA 92521, USA
- L. Napolitano
- ORCiD
- INAF—Osservatorio Astronomico di Roma , via di Frascati 33, 00078 Monte Porzio Catone, Italy; Dipartimento di Fisica, Università di Roma Sapienza , Città Universitaria di Roma—Sapienza, Piazzale Aldo Moro, 2, 00185, Roma, Italy
- Jeffrey A. Newman
- ORCiD
- Department of Physics and Astronomy and PITT PACC, University of Pittsburgh , Pittsburgh, PA 15260, USA
- Laura Pentericci
- ORCiD
- INAF—Osservatorio Astronomico di Roma , via di Frascati 33, 00078 Monte Porzio Catone, Italy
- Pablo G. Pérez-González
- ORCiD
- Centro de Astrobiología (CAB) , CSIC-INTA, Ctra. de Ajalvir km 4, Torrejón de Ardoz, E-28850, Madrid, Spain
- Jonathan R. Trump
- ORCiD
- Department of Physics, 196 Auditorium Road, Unit 3046, University of Connecticut , Storrs, CT 06269, USA
- Stephen M. Wilkins
- ORCiD
- Astronomy Centre, University of Sussex , Falmer, Brighton, BN1 9QH, UK; Institute of Space Sciences and Astronomy, University of Malta , Msida MSD 2080, Malta
- L. Y. Aaron Yung
- ORCiD
- Space Telescope Science Institute , 3700 San Martin Drive, Baltimore, MD 21218, USA
- DOI
- https://doi.org/10.3847/1538-4357/ad5015
- Journal volume & issue
-
Vol. 971,
no. 1
p. 21
Abstract
Ultraviolet (UV; rest-frame ∼1200–2000 Å) spectra provide a wealth of diagnostics to characterize fundamental galaxy properties, such as their chemical enrichment, the nature of their stellar populations, and their amount of Lyman-continuum (LyC) radiation. In this work, we leverage publicly released JWST data to construct the rest-frame UV-to-optical composite spectrum of a sample of 63 galaxies at 5.6 < z < 9, spanning a wavelength range from 1500 to 5200 Å. Based on the composite spectrum, we derive an average dust attenuation $E{(B-V)}_{\mathrm{gas}}\,=\,{0.10}_{-0.11}^{+0.10}$ from H β /H γ , an electron density ${n}_{e}={570}_{-290}^{+510}$ cm ^−3 from the [O ii ] doublet ratio, an electron temperature ${T}_{e}={16700}_{-1500}^{+1500}$ K from the [O iii ] λ 4363/[O iii ] λ 5007 ratio, and an ionization parameter $\mathrm{log}(U)=-{2.15}_{-0.03}^{+0.03}$ from the [O iii ]/[O ii ] ratio. Using a direct T _e method, we calculate an oxygen abundance $12+\mathrm{log}({\rm{O}}/{\rm{H}})\,=\,7.67\pm 0.08$ and a carbon-to-oxygen (C/O) abundance ratio $\mathrm{log}({\rm{C}}/{\rm{O}})\,=\,-{0.86}_{-0.10}^{+0.13}$ . This C/O ratio is smaller than compared to z = 0 and z = 2–4 star-forming galaxies, albeit with moderate significance. This indicates the reionization-era galaxies might be undergoing a rapid buildup of stellar mass with high specific star formation rates. A UV diagnostic based on the ratios of C iii ] λ λ 1907, 1909/He ii λ 1640 versus O iii ] λ 1666/He ii λ 1640 suggests that the star formation is the dominant source of ionization, similar to the local extreme dwarf galaxies and z ∼ 2–4 He ii –detected galaxies. The [O iii ]/[O ii ] and C iv /C iii ] ratios of the composite spectrum are marginally larger than the criteria used to select galaxies as LyC leakers, suggesting that some of the galaxies in our sample are strong contributors to the reionizing radiation.
Keywords
- High-redshift galaxies
- Galaxy chemical evolution
- Emission line galaxies
- Galaxy spectroscopy
- Reionization
