Double Trouble: Two spectroscopically confirmed low-mass quiescent galaxies at z>5 in overdensities

Abstract

We present the discovery of two low-mass, high-redshift, quiescent galaxies, GS-z5-Q1 and COS-z5-Q1, using JWST NIRSpec spectroscopy alongside NIRCam and MIRI photometry. Observed at a redshift of z=5.39 and z=5.11 respectively, and with stellar masses of $10^{9.6}{\mathrm{M}}_{\odot }$ and $10^{9.5}{\mathrm{M}}_{\odot }$, GS-z5-Q1 and COS-z5-Q1 are two of the most distant quiescent galaxies spectroscopically confirmed to-date, and are by far the least massive ($\sim 10\times$ lower mass). Full spectrophotometric modelling reveals that COS-z5-Q1 appears to have quenched more than 300Myr prior to observation ($z\sim 7$) and has a formation redshift of around z$\sim$11, whilst GS-z5-Q1 formed and quenched in a single burst around 150Myr prior to observation ($z\sim 6$). GS-z5-Q1 is found to lie near the centre of a known high-z overdensity in GOODS-S, as would be expected by galaxy formation models, while COS-z5-Q1 lies towards the outskirts of an overdense region. This highlights the role that environment could play in accelerating galaxy evolutionary processes and could possibly be linked to the galaxies' quiescent nature. By modelling their stellar populations, we show that these types of low-mass quiescent galaxies could potentially be descendants of the higher-z "mini-quenched" galaxies. The discovery of these two low-mass $z>5$ quiescent galaxies illuminates a previously undiscovered galaxy population and motivates dedicated follow-up surveys to investigate the overall population.

10 pages, 6 figures, Accepted for publication in A&A

References in corpus (37)

• Array Programming with NumPy
• Mass and environment as drivers of galaxy evolution in SDSS and zCOSMOS and the origin of the Schechter function
• The propagation of uncertainties in stellar population synthesis modeling I: The relevance of uncertain aspects of stellar evolution and the IMF to the derived physical properties of galaxies
• EAZY: A Fast, Public Photometric Redshift Code
• The Herschel view of the dominant mode of galaxy growth from z=4 to the present day
• Stellar Population Inference with Prospector
• Structure and star formation in galaxies out to z=3: evidence for surface density dependent evolution and upsizing
• Evidence for Mature Bulges and an Inside-out Quenching Phase 3 Billion Years After the Big Bang
• A massive quiescent galaxy at redshift 4.658
• On the Stellar Populations of Galaxies at z=9-11: The Growth of Metals and Stellar Mass at Early Times
• An Atlas of Color-selected Quiescent Galaxies at $z>3$ in Public $JWST$ Fields
• Charting the evolution of the ages and metallicities of massive galaxies since z=0.7
• Effect of local environment and stellar mass on galaxy quenching and morphology at $0.5<z<2.0$
• Dense cores in galaxies out to z=2.5 in SDSS, UltraVISTA, and the five 3D-HST/CANDELS fields
• A massive galaxy that formed its stars at $z\sim 11$
• RUBIES: a complete census of the bright and red distant Universe with JWST/NIRSpec
• The JWST-PRIMAL Legacy Survey. A JWST/NIRSpec reference sample for the physical properties and Lyman-$\alpha$ absorption and emission of $\sim 500$ galaxies at $z=5.5-13.4$
• Spectroscopic Confirmation of a Protocluster at $z=3.37$ with a High Fraction of Quiescent Galaxies
• Mini-quenching of $z=4-8$ galaxies by bursty star formation
• GA-NIFS: The core of an extremely massive proto-cluster at the Epoch of Reionization probed with JWST/NIRSpec
• The eventful life of a luminous galaxy at z = 14: metal enrichment, feedback, and low gas fraction?
• The JWST Advanced Deep Extragalactic Survey: Discovery of an Extreme Galaxy Overdensity at $z=5.4$ with JWST/NIRCam in GOODS-S
• A lensed protocluster candidate at $z=7.66$ identified in JWST observations of the galaxy cluster SMACS0723-7327
• Recalibrating the Cosmic Star Formation History
• Identification of High-Redshift Galaxy Overdensities in GOODS-N and GOODS-S
• JADES: Differing assembly histories of galaxies -- Observational evidence for bursty SFHs and (mini-)quenching in the first billion years of the Universe
• Unveiling the hidden universe with JWST: The contribution of dust-obscured galaxies to the stellar mass function at $z\sim 3-8$
• Zapped then Napped? A rapidly quenched remnant leaker candidate with a steep spectroscopic ${\beta }_{UV}$ slope at z=8.5
• Gas outflows in two recently quenched galaxies at z = 4 and 7
• Exploring over 700 massive quiescent galaxies at z = 2-7: Demographics and stellar mass functions
• DAWN JWST Archive: Morphology from profile fitting of over 340 000 galaxies in major fields
• A merging pair of massive quiescent galaxies at $z=3.44$ in the Cosmic Vine
• Explaining ultra-massive quiescent galaxies at $3<z<5$ in the context of their environments
• PRIMER & JADES reveal an abundance of massive quiescent galaxies at 2 < z < 5
• JWST/NIRSpec spectroscopy of intermediate-mass quiescent galaxies at $z\sim 3-4$
• A systematic search for dormant galaxies at z~5-7 from the JWST NIRSpec archive
• Dust removal timescale in galaxies across cosmic time

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• A census of quiescent galaxies across $0.5<z<8$ with JWST/MIRI: Mass-dependent number density evolution of quiescent galaxies in the early Universe
• Cosmic Vine: High abundance of massive galaxies and dark matter halos in a forming cluster at z=3.44
• Dynamical properties and star formation history of a low-mass quenched galaxy at Cosmic Noon