A population of faint, old, and massive quiescent galaxies at $$3<z<4$$ revealed by JWST NIRSpec Spectroscopy

Abstract

Here we present a sample of 12 massive quiescent galaxy candidates at $$z\sim 3-4$$ z ∼ 3 - 4 observed with the James Webb Space Telescope (JWST) Near Infrared Spectrograph (NIRSpec). These galaxies were pre-selected from the Hubble Space Telescope imaging and 10 of our sources were unable to be spectroscopically confirmed by ground based spectroscopy. By combining spectroscopic data from NIRSpec with multi-wavelength imaging data from the JWST Near Infrared Camera (NIRCam), we analyse their stellar populations and their formation histories. We find that all of our galaxies classify as quiescent based on the reconstruction of their star formation histories but show a variety of quenching timescales and ages. All our galaxies are massive ($$\sim 0.1-1.2\times 10^{11}$$ ∼ 0.1 - 1.2 × 10 11 M$$_\odot$$ ⊙ ), with masses comparable to massive galaxies in the local Universe. We find that the oldest galaxy in our sample formed $$\sim 1.0\times 10^{11}$$ ∼ 1.0 × 10 11 M$$_\odot$$ ⊙ of mass within the first few hundred million years of the Universe and has been quenched for more than a billion years by the time of observation at $$z\sim 3.2$$ z ∼ 3.2 ($$\sim 2$$ ∼ 2 billion years after the Big Bang). Our results point to very early formation of massive galaxies requiring a high conversion rate of baryons to stars in the early Universe.

A Massive Quiescent Galaxy in a Group Environment at z = 4.53

“…The young age of our galaxy is likely due to a selection effect; we intentionally targeted the brightest candidate in the K s band (which covers the Balmer break), and thus we tend to select galaxies with a prominent Balmer break, leading us to young post-starbursts. It is interesting that old quiescent galaxies show little dust attenuation (A V ∼ 0: e.g., Nanayakkara et al 2024;Carnall et al 2023b), while young ones suffer from a larger amount of attenuation (A V ∼ 0.7: this work, Valentino et al 2020). This indicates that post-starburst galaxies have residual dust.…”

“…Relation between formation redshift (z form ) at which the galaxy formed 50% of total stellar mass and observed redshift (z spec ). We plot COSMOS-1047519 (the red star) and spectroscopic samples of massive quiescent galaxies at z > 3 from previous research (Schreiber et al 2018;Forrest et al 2020b;Valentino et al 2020;Nanayakkara et al 2024;Carnall et al 2023b). Carnall et al (2023b) uses a mass-weighted mean formation time to define z form .…”

“…Thanks to the recent development of sensitive near-infrared spectrographs, massive quiescent galaxies at up to z ∼ 4 are spectroscopically confirmed (e.g., Glazebrook et al 2017;Schreiber et al 2018;Forrest et al 2020aForrest et al , 2020bD'Eugenio et al 2020D'Eugenio et al , 2021Valentino et al 2020;Nanayakkara et al 2024;Antwi-Danso et al 2023;Tanaka et al 2023). This epoch is consistent with the formation epoch inferred from the local elliptical galaxies (Thomas et al 2010), and the identification of massive quiescent galaxies at z > 4 is critical to understanding their quenching mechanism.…”

Size–Stellar Mass Relation and Morphology of Quiescent Galaxies at z ≥ 3 in Public JWST Fields

“…Recently, massive quiescent galaxies have been found even at z  3-4 (Glazebrook et al 2017;Schreiber et al 2018;Tanaka et al 2019;Forrest et al 2020;Valentino et al 2020;D'Eugenio et al 2021;Carnall et al 2023aCarnall et al , 2023bNanayakkara et al 2024). The morphology of some of these galaxies is also explored using ground-based telescopes.…”

The First Quenched Galaxies: When and How?

“…The cessation of star formation in galaxies has drawn considerable attention in recent years, especially given the large numbers of quiescent massive galaxies that have been found in the early Universe (Glazebrook et al 2017;Schreiber et al 2018;Girelli et al 2019;Merlin et al 2019;Nanayakkara et al 2024) when the timescale available to assemble and quench these systems is short. Spectroscopic studies suggest that these galaxies experience short periods of intense star formation, grow up to a stellar mass of 10 11 M e in the first 1 or 2 billion yr of the Universe, and then stop forming stars within a few tens of million years (Forrest et al 2020;Valentino et al 2020;Carnall et al 2023a;Kakimoto et al 2023).…”