Extreme emission line galaxies detected in JADES <i>JWST</i>/NIRSpec – I. Inferred galaxy properties

ABSTRACT Extreme emission line galaxies (EELGs) exhibit large equivalent widths (EW) in their rest-optical emission lines ([O iii]$\lambda 5007$ or H $\alpha$ rest-frame EW$\gt 750$ Å) which can be tied to a recent upturn in star formation rate (SFR), due to the sensitivity of the nebular line emission and the rest-optical continuum to young ($\lt 10$ Myr) and evolved stellar populations, respectively. By studying a sample of 85 star-forming galaxies (SFGs), spanning the redshift and magnitude interval $3 \lt z\lt 9.5$ and $-16\gt $M$\rm _{UV}\gt -21$, in the JWST Advanced Deep Extragalactic Survey (JADES) with NIRSpec/prism spectroscopy, we determine that SFGs initiate an EELG phase when entering a significant burst of star formation, with the highest EWs observed in EELGs with the youngest luminosity-weighted ages ($\lt 5$ Myr) and the highest burst intensity (those with the greatest excess between their current and long-term average SFR). We spectroscopically confirm that a greater proportion of SFGs are in an EELG phase at high redshift in our UV-selected sample ($61\pm 4~{{\ \rm per\ cent}}$ in our $z\gt 5.7$ high-redshift bin, compared to $23^{+4}_{-1}\%$ in our lowest redshift bin $3\lt z\lt 4.1$) due to the combined evolution of metallicity, ionization parameter, and star formation histories with redshift. We report that the EELGs within our sample exhibit a higher average ionization efficiency ($\log _{10}(\xi _\mathrm{ion}^\mathrm{HII}/{\rm erg^{-1}Hz}) =25.5\pm 0.2$) than the non-EELGs. High-redshift EELGs therefore comprise a population of efficient ionizing photon producers. Additionally, we report that 53 per cent (9/17) of EELGs at $z\gt 5.7$ have observed Ly $\alpha$ emission, potentially lying within large ionized regions. The high detection rate of Ly $\alpha$ emitters in our EELG selection suggests that the physical conditions associated with entering an EELG phase also promote the escape of Ly $\alpha$ photons.

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Publication Details

Journal
Monthly Notices of the Royal Astronomical Society
Published
2024-10-24
DOI
https://doi.org/10.1093/mnras/stae2430
Citations
53
Primary Topic
Galaxies: Formation, Evolution, Phenomena
Type
article
Field-Weighted Citation Impact
17.57

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article

Extreme emission line galaxies detected in JADES JWST/NIRSpec – I. Inferred galaxy properties

Nimisha Kumari, Joris Witstok, Santiago Arribas, Benjamin D. Johnson et al.
53 citations
Monthly Notices of the Royal Astronomical Society
Galaxies: Formation, Evolution, Phenomena
17.57
article

Extreme emission line galaxies detected in JADES JWST/NIRSpec – I. Inferred galaxy properties

Nimisha Kumari, Joris Witstok, Santiago Arribas, Benjamin D. Johnson, Stefano Carniani, Kevin Hainline, Jacopo Chevallard, Sandro Tacchella, Alex J. Cameron, Chris J. Willott, Gareth C. Jones, Charlotte Simmonds, S. Charlot, Mirko Curti, Christina C. Williams, Tobias J. Looser, Isaac Laseter, Aayush Saxena, Irene Shivaei, Daniel J. Eisenstein, Hannah Übler, Stacey Alberts, Zuyi Chen, Jan Scholtz, Emma Curtis-Lake, Kristan Boyett, Andrew J. Bunker, Brant E. Robertson, Marcia Rieke, Michael V. Maseda, Renske Smit, Ryan Endsley, Imaan E. B. Wallace, Ryan Hausen, Daniel P. Stark, Eiichi Egami
article en
53 citations

Abstract

ABSTRACT Extreme emission line galaxies (EELGs) exhibit large equivalent widths (EW) in their rest-optical emission lines ([O iii]$\lambda 5007$ or H $\alpha$ rest-frame EW$\gt 750$ Å) which can be tied to a recent upturn in star formation rate (SFR), due to the sensitivity of the nebular line emission and the rest-optical continuum to young ($\lt 10$ Myr) and evolved stellar populations, respectively. By studying a sample of 85 star-forming galaxies (SFGs), spanning the redshift and magnitude interval $3 \lt z\lt 9.5$ and $-16\gt $M$\rm _{UV}\gt -21$, in the JWST Advanced Deep Extragalactic Survey (JADES) with NIRSpec/prism spectroscopy, we determine that SFGs initiate an EELG phase when entering a significant burst of star formation, with the highest EWs observed in EELGs with the youngest luminosity-weighted ages ($\lt 5$ Myr) and the highest burst intensity (those with the greatest excess between their current and long-term average SFR). We spectroscopically confirm that a greater proportion of SFGs are in an EELG phase at high redshift in our UV-selected sample ($61\pm 4~{{\ \rm per\ cent}}$ in our $z\gt 5.7$ high-redshift bin, compared to $23^{+4}_{-1}\%$ in our lowest redshift bin $3\lt z\lt 4.1$) due to the combined evolution of metallicity, ionization parameter, and star formation histories with redshift. We report that the EELGs within our sample exhibit a higher average ionization efficiency ($\log _{10}(\xi _\mathrm{ion}^\mathrm{HII}/{\rm erg^{-1}Hz}) =25.5\pm 0.2$) than the non-EELGs. High-redshift EELGs therefore comprise a population of efficient ionizing photon producers. Additionally, we report that 53 per cent (9/17) of EELGs at $z\gt 5.7$ have observed Ly $\alpha$ emission, potentially lying within large ionized regions. The high detection rate of Ly $\alpha$ emitters in our EELG selection suggests that the physical conditions associated with entering an EELG phase also promote the escape of Ly $\alpha$ photons.

Monthly Notices of the Royal Astronomical SocietyVol. 535(2)
Herzberg Institute of Astrophysics (CA), University of Copenhagen (DK), Centre National de la Recherche Scientifique (FR), Space Telescope Science Institute (US), European Southern Observatory (DE), University of Wisconsin–Madison (US), University of Arizona (US), University of Hertfordshire (GB), Johns Hopkins University (US), Scuola Normale Superiore (IT), The University of Melbourne (AU), University of California, Santa Cruz (US), University of Cambridge (GB), Institut d'Astrophysique de Paris (FR), Sorbonne Université (FR), University of Oxford (GB), Max Planck Institute for Extraterrestrial Physics (DE), Center for Astrophysics Harvard & Smithsonian (US), Centro de Astrobiología (ES), NSF NOIRLab (US), ARC Centre of Excellence for All-sky Astrophysics (AU), University College London (GB), Liverpool John Moores University (GB), The University of Texas at Austin (US)
National Science Foundation, National Aeronautics and Space Administration, Johns Hopkins University, MultiCare Institute for Research and Innovation, Space Telescope Science Institute, UK Research and Innovation, European Commission, National Research Foundation, Danmarks Grundforskningsfond, Nuclear Safety and Security Commission, Isaac Newton Trust, Ministerio de Ciencia e Innovación, Mitutoyo Association for Science and Technology, Goddard Space Flight Center, Science and Technology Facilities Council, Australian Research Council, Agencia Estatal de Investigación, H2020 European Research Council
Openalex Percentile: Top 0%
Galaxies: Formation, Evolution, Phenomena
17.57
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