JADES: Differing assembly histories of galaxies

Observational evidence for bursty star formation histories and (mini-)quenching in the first billion years of the Universe

¹ Kavli Institute for Cosmology, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK
² Cavendish Laboratory, University of Cambridge, 19 JJ Thomson Avenue, Cambridge CB3 0HE, UK
³ Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK
⁴ European Southern Observatory, Karl-Schwarzschild-Strasse 2, D-85748 Garching bei Muenchen, Germany
⁵ Centro de Astrobiología (CAB), CSIC-INTA, Cra. de Ajalvir Km. 4, 28850 Torrejón de Ardoz, Madrid, Spain
⁶ Department of Physics and Astronomy, University of Manitoba, Winnipeg, MB R3T 2N2, Canada
⁷ Cosmic Dawn Center (DAWN), Copenhagen, Denmark
⁸ Niels Bohr Institute, University of Copenhagen, Jagtvej 128, DK-2200 Copenhagen, Denmark
⁹ Steward Observatory University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721, USA
¹⁰ School of Physics, University of Melbourne, Parkville, 3010 VIC, Australia
¹¹ ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), Canberra, Australia
¹² Department of Physics, University of Oxford, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH, UK
¹³ Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy
¹⁴ Sorbonne Université, CNRS, UMR 7095, Institut d’Astrophysique de Paris, 98 bis bd Arago, 75014 Paris, France
¹⁵ Centre for Astrophysics Research, Department of Physics, Astronomy and Mathematics, University of Hertfordshire, Hatfield AL10 9AB, UK
¹⁶ Center for Astrophysics | Harvard & Smithsonian, 60 Garden St., Cambridge, MA 02138, USA
¹⁷ Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg, Germany
¹⁸ AURA for European Space Agency, Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21210, USA
¹⁹ Department for Astrophysical and Planetary Science, University of Colorado, Boulder, CO 80309, USA
²⁰ Department of Astronomy and Astrophysics University of California, Santa Cruz, 1156 High Street, Santa Cruz CA 96054, USA
²¹ Astrophysics Research Institute, Liverpool John Moores University, 146 Brownlow Hill, Liverpool L3 5RF, UK
²² NSF’s National Optical-Infrared Astronomy Research Laboratory, 950 North Cherry Avenue, Tucson, AZ 85719, USA
²³ NRC Herzberg, 5071 West Saanich Rd, Victoria, BC V9E 2E7, Canada

^⋆ Corresponding author: tjl54@cam.ac.uk

Received: 5 June 2023
Accepted: 22 December 2024

Abstract

We used deep NIRSpec spectroscopic data from the JADES survey to derive the star formation histories (SFHs) of a sample of 200 galaxies at 0.6 < z < 11 that span stellar masses from 10⁶ to 10^9.5 M_⊙. We found that galaxies at high redshift, galaxies above the main sequence (MS), and low-mass galaxies tend to host younger stellar populations than their lower-redshift, below the MS, and more massive counterparts. Interestingly, the correlation between age, stellar mass M_*, and star formation rate (SFR) existed even earlier than cosmic noon, out to the earliest cosmic epochs. However, these trends have a large scatter. There are also examples of young stellar populations below the MS, which indicates recent (bursty) star formation in evolved systems. We further explored the burstiness of the SFHs by using the ratio of the SFR averaged over the last 10 Myr and averaged between 10 Myr and 100 Myr before the epoch of observation (SFR_cont, 10/SFR_cont, 90). We found that high-redshift and low-mass galaxies have particularly bursty SFHs, while more massive and lower-redshift systems evolve more steadily. We also present the discovery of another (mini-)quenched galaxy at z = 4.4, which might be only temporarily quiescent as a consequence of the extremely bursty evolution. Finally, we also found a steady decline in the dust reddening of the stellar population as the earliest cosmic epochs are approached, although some dust reddening is still observed in some of the highest-redshift and most strongly star-forming systems.