<i>JWST</i>/NIRSpec WIDE survey: a <i>z</i> = 4.6 low-mass star-forming galaxy hosting a jet-driven shock with low ionization and solar metallicity

ABSTRACT We present NIRSpec/micro-shutter assembly observations from the JWST large-area survey WIDE, targeting the rest-frame UV–optical spectrum of Ulema, a radio-active galactic nucleus host at redshift $z=4.6348$. The low-resolution prism spectrum displays high equivalent width nebular emission, with remarkably high ratios of low-ionization species of oxygen, nitrogen, and sulphur, relative to hydrogen; auroral O$^+$ emission is clearly detected, possibly also C$^+$. From the high-resolution grating spectrum, we measure a gas velocity dispersion of $\sigma \sim 400$$\mathrm{km\, s^{-1}}$, broad enough to rule out star-forming gas in equilibrium in the gravitational potential of the galaxy. Diagnostics based on emission-line ratios suggest that the nebular emission is due to a shock which ran out of pre-shock gas. To infer the physical properties of the system, we model simultaneously the galaxy spectral energy distribution and shock-driven line emission under a Bayesian framework. We find a relatively low-mass, star-forming system ($M_\star = 1.4 \times 10^{10}~{\rm M}_\odot$, $\mathrm{SFR} = 70~{\rm M}_\odot ~{\rm yr^{-1}}$), where shock-driven emission contributes 50 per cent to the total H β luminosity. The nebular metallicity is near solar – three times higher than that predicted by the mass–metallicity relation at $z=4.6$, possibly related to fast-paced chemical evolution near the galaxy nucleus. We find no evidence for a recent decline in the star-formation rate of the galaxy, meaning that, already at this early epoch, fast radio-mode active galactic nucleus feedback was poorly coupled with the bulk of the star-forming gas; therefore, most of the feedback energy must end up in the galaxy halo, setting the stage for future quenching.

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Journal
Monthly Notices of the Royal Astronomical Society
Published
2024-11-12
DOI
https://doi.org/10.1093/mnras/stae2545
Citations
7
Primary Topic
Galaxies: Formation, Evolution, Phenomena
Type
article
Field-Weighted Citation Impact
2.32

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article

JWST/NIRSpec WIDE survey: a z = 4.6 low-mass star-forming galaxy hosting a jet-driven shock with low ionization and solar metallicity

Francesco D’Eugenio, Jakob M. Helton, V. H. Mahatma, R. Maiolino et al.
7 citations
Monthly Notices of the Royal Astronomical Society
Galaxies: Formation, Evolution, Phenomena
2.32
article

JWST/NIRSpec WIDE survey: a z = 4.6 low-mass star-forming galaxy hosting a jet-driven shock with low ionization and solar metallicity

Francesco D’Eugenio, Jakob M. Helton, V. H. Mahatma, R. Maiolino, Giovanni Mazzolari, Stefano Carniani, Jan Scholtz, Sandro Tacchella, Xihan Ji, Hannah Übler, R. Morganti, Andrew J. Bunker, Michael V. Maseda, C. N. Tadhunter, Anna de Graaff, Giacomo Venturi, Eleonora Parlanti, Gareth C Jones
article en
7 citations

Abstract

ABSTRACT We present NIRSpec/micro-shutter assembly observations from the JWST large-area survey WIDE, targeting the rest-frame UV–optical spectrum of Ulema, a radio-active galactic nucleus host at redshift $z=4.6348$. The low-resolution prism spectrum displays high equivalent width nebular emission, with remarkably high ratios of low-ionization species of oxygen, nitrogen, and sulphur, relative to hydrogen; auroral O$^+$ emission is clearly detected, possibly also C$^+$. From the high-resolution grating spectrum, we measure a gas velocity dispersion of $\sigma \sim 400$$\mathrm{km\, s^{-1}}$, broad enough to rule out star-forming gas in equilibrium in the gravitational potential of the galaxy. Diagnostics based on emission-line ratios suggest that the nebular emission is due to a shock which ran out of pre-shock gas. To infer the physical properties of the system, we model simultaneously the galaxy spectral energy distribution and shock-driven line emission under a Bayesian framework. We find a relatively low-mass, star-forming system ($M_\star = 1.4 \times 10^{10}~{\rm M}_\odot$, $\mathrm{SFR} = 70~{\rm M}_\odot ~{\rm yr^{-1}}$), where shock-driven emission contributes 50 per cent to the total H β luminosity. The nebular metallicity is near solar – three times higher than that predicted by the mass–metallicity relation at $z=4.6$, possibly related to fast-paced chemical evolution near the galaxy nucleus. We find no evidence for a recent decline in the star-formation rate of the galaxy, meaning that, already at this early epoch, fast radio-mode active galactic nucleus feedback was poorly coupled with the bulk of the star-forming gas; therefore, most of the feedback energy must end up in the galaxy halo, setting the stage for future quenching.

Monthly Notices of the Royal Astronomical SocietyVol. 536(1)
University of Wisconsin–Madison (US), University of Arizona (US), Scuola Normale Superiore (IT), University of Groningen (NL), University of Cambridge (GB), University of Oxford (GB), Bridge University (SS), AstroTec Holding (Netherlands) (NL), Max Planck Institute for Astronomy (DE), Astronomical Institute of the Slovak Academy of Sciences (SK), Osservatorio di Astrofisica e Scienza dello Spazio, University College London (GB), University of Sheffield (GB), Netherlands Institute for Radio Astronomy (NL), University of Bologna (IT)
National Science Foundation, National Aeronautics and Space Administration, Kavli Foundation, Wisconsin Alumni Research Foundation, Royal Society, European Commission, Danmarks Grundforskningsfond, Ministero dell’Istruzione, dell’Università e della Ricerca, Isaac Newton Trust, Science and Technology Facilities Council
Affordable and clean energy
Openalex Percentile: Top 12%
Galaxies: Formation, Evolution, Phenomena
2.32
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