Local and low-redshift (z < 3) galaxies are known to broadly follow a bimodal distribution: actively star-forming galaxies with relatively stable star-formation rates and passive systems. These two populations are connected by galaxies in relatively slow transition. By contrast, theory predicts that star formation was stochastic at early cosmic times and in low-mass systems1–4. These galaxies transitioned rapidly between starburst episodes and phases of suppressed star formation, potentially even causing temporary quiescence—so-called mini-quenching events5,6. However, the regime of star-formation burstiness is observationally highly unconstrained. Directly observing mini-quenched galaxies in the primordial Universe is therefore of utmost importance to constrain models of galaxy formation and transformation7,8. Early quenched galaxies have been identified out to redshift z < 5 (refs. 9–12) and these are all found to be massive (M⋆ > 1010 M⊙) and relatively old. Here we report a (mini-)quenched galaxy at z = 7.3, when the Universe was only 700 Myr old. The JWST/NIRSpec spectrum is very blue (U–V = 0.16 ± 0.03 mag) but exhibits a Balmer break and no nebular emission lines. The galaxy experienced a short starburst followed by rapid quenching; its stellar mass (4–6 × 108 M⊙) falls in a range that is sensitive to various feedback mechanisms, which can result in perhaps only temporary quenching.

A recently quenched galaxy 700 million years after the Big Bang

Carniani S.;
2024

Abstract

Local and low-redshift (z < 3) galaxies are known to broadly follow a bimodal distribution: actively star-forming galaxies with relatively stable star-formation rates and passive systems. These two populations are connected by galaxies in relatively slow transition. By contrast, theory predicts that star formation was stochastic at early cosmic times and in low-mass systems1–4. These galaxies transitioned rapidly between starburst episodes and phases of suppressed star formation, potentially even causing temporary quiescence—so-called mini-quenching events5,6. However, the regime of star-formation burstiness is observationally highly unconstrained. Directly observing mini-quenched galaxies in the primordial Universe is therefore of utmost importance to constrain models of galaxy formation and transformation7,8. Early quenched galaxies have been identified out to redshift z < 5 (refs. 9–12) and these are all found to be massive (M⋆ > 1010 M⊙) and relatively old. Here we report a (mini-)quenched galaxy at z = 7.3, when the Universe was only 700 Myr old. The JWST/NIRSpec spectrum is very blue (U–V = 0.16 ± 0.03 mag) but exhibits a Balmer break and no nebular emission lines. The galaxy experienced a short starburst followed by rapid quenching; its stellar mass (4–6 × 108 M⊙) falls in a range that is sensitive to various feedback mechanisms, which can result in perhaps only temporary quenching.
2024
Settore FIS/05 - Astronomia e Astrofisica
   Winds in galaxies.
   WINGS
   European Commission
   Grant Agreement n. 101040227

   Star formation quenching and feedback in galaxies throughout the cosmic epochs
   QUENCH
   European Commission
   Horizon 2020 Framework Programme
   695671

   Finding the most distant galaxies with NIRSpec guaranteed time on the James Webb Space Telescope
   FirstGalaxies
   European Commission
   Horizon 2020 Framework Programme
   789056
File in questo prodotto:
File Dimensione Formato  
s41586-024-07227-0_compressed.pdf

accesso aperto

Tipologia: Published version
Licenza: Creative Commons
Dimensione 1.47 MB
Formato Adobe PDF
1.47 MB Adobe PDF

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11384/143443
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 14
  • ???jsp.display-item.citation.isi??? ND
  • OpenAlex ND
social impact