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Here we present a sample of 12 massive quiescent galaxy candidates at 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 ( ∼ 0.1 - 1.2 × 10 11 M ⊙ ), with masses comparable to massive galaxies in the local Universe. We find that the oldest galaxy in our sample formed ∼ 1.0 × 10 11 M ⊙ 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 ∼ 3.2 ( ∼ 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.

Galactic turbulence: disk galaxies ancient and modern We live in a disk galaxy, yet have a very poor understanding of how they form — not helped by the fact that disk galaxies in the early Universe seem rather different to our Milky Way. Many of the disk galaxies of the early Universe are surprisingly large and far more turbulent than the Milky Way and other modern spirals. Now the discovery of a new sample of similarly unusual disk galaxies persisting to the present day adds a significant new element to this debate. In these galaxies, resembling the 'turbulent disks' observed in the early Universe, velocity dispersions correlate with their star-formation rates, which suggests that star formation itself is the energetic driver of galaxy disk turbulence at all cosmic epochs. High-resolution observations of early galaxies have shown that two-thirds are massive rotating disk galaxies with velocity dispersions typically five times higher than in today's galaxies. These authors report observations of a sample of rare, high-velocity-dispersion disk galaxies. They find that their velocity dispersions are correlated with their star formation rates, but not their masses or gas fractions, suggesting that star formation is the energetic driver of galaxy disk turbulence at all cosmic epochs. Observations of star formation and kinematics in early galaxies at high spatial and spectral resolution have shown that two-thirds are massive rotating disk galaxies 1 , 2 , 3 , 4 , 5 , with the remainder being less massive non-rotating objects 2 , 4 , 6 , 7 , 8 . The line-of-sight-averaged velocity dispersions are typically five times higher than in today’s disk galaxies. This suggests that gravitationally unstable, gas-rich disks in the early Universe are fuelled by cold, dense accreting gas flowing along cosmic filaments and penetrating hot galactic gas halos 9 , 10 . These accreting flows, however, have not been observed 11 , and cosmic accretion cannot power the observed level of turbulence 12 . Here we report observations of a sample of rare, high-velocity-dispersion disk galaxies in the nearby Universe where cold accretion is unlikely to drive their high star formation rates. We find that their velocity dispersions are correlated with their star formation rates, but not their masses or gas fractions, which suggests that star formation is the energetic driver of galaxy disk turbulence at all cosmic epochs.

Massive quiescent galaxies (MQGs) at redshifts z > 3 present a profound challenge to our understanding of galaxy formation and evolution. These galaxies undergo rapid and intense star formation followed by swift quenching very early in cosmic history, resulting in the formation of compact galaxies with half-light radii smaller than 1 kpc. New observations, particularly from the James Webb Space Telescope (JWST), have rapidly advanced our knowledge of their abundance, possible formation pathways, and physical properties. However, current theoretical models still struggle to replicate the observed number densities and characteristics of these galaxies. This review attempts to consolidate recent observational breakthroughs, discusses the comparison with theoretical models, and highlights key unresolved questions. An especially interesting development is the discovery of sub-populations of even older and early forming (at z > 7) quiescent galaxies which pose particular challenges and add to the ledger of the ‘too much too soon’ galaxy and AGN problems revealed by JWST. I outline my own views on key future research directions to unravel the mysteries of MQGs and their role in the broader context of cosmic evolution.

Hierarchical galaxy formation is the model whereby massive galaxies form from an assembly of smaller units 1 . The most massive objects therefore form last. The model succeeds in describing the clustering of galaxies 2 , but the evolutionary history of massive galaxies, as revealed by their visible stars and gas, is not accurately predicted. Near-infrared observations (which allow us to measure the stellar masses of high-redshift galaxies 3 ) and deep multi-colour images indicate that a large fraction of the stars in massive galaxies form in the first 5 Gyr (refs 4–7 ), but uncertainties remain owing to the lack of spectra to confirm the redshifts (which are estimated from the colours) and the role of obscuration by dust. Here we report the results of a spectroscopic redshift survey that probes the most massive and quiescent galaxies back to an era only 3 Gyr after the Big Bang. We find that at least two-thirds of massive galaxies have appeared since this era, but also that a significant fraction of them are already in place in the early Universe.

The large-scale structure in the distribution of galaxies is thought to arise from the gravitational instability of small fluctuations in the initial density field of the Universe. A key test of this hypothesis is that forming superclusters of galaxies should generate a systematic infall of other galaxies. This would be evident in the pattern of recessional velocities, causing an anisotropy in the inferred spatial clustering of galaxies. Here we report a precise measurement of this clustering, using the redshifts of more than 141,000 galaxies from the two-degree-field (2dF) galaxy redshift survey. We determine the parameter β = Ω 0.6 / b = 0.43 ± 0.07, where Ω is the total mass-density parameter of the Universe and b is a measure of the ‘bias’ of the luminous galaxies in the survey. (Bias is the difference between the clustering of visible galaxies and of the total mass, most of which is dark.) Combined with the anisotropy of the cosmic microwave background, our results favour a low-density Universe with Ω ≈ 0.3.

While quiescent galaxies have comparable amounts of cool gas in their outer circumgalactic medium (CGM) compared to star-forming galaxies, they have significantly less interstellar gas. However, open questions remain on the processes causing galaxies to stop forming stars and stay quiescent. Theories suggest dynamical interactions with the hot corona prevent cool gas from reaching the galaxy, therefore predicting the inner regions of quiescent galaxy CGMs are devoid of cool gas. However, there is a lack of understanding of the inner regions of CGMs due to the lack of spatial information in quasar-sightline methods. We present integral-field spectroscopy probing 10–20 kpc (2.4–4.8 R e ) around a massive quiescent galaxy using a gravitationally lensed star-forming galaxy. We detect absorption from Magnesium (MgII) implying large amounts of cool atomic gas (10 8.4 –10 9.3 M ⊙ with T~10 4 Kelvin), in comparable amounts to star-forming galaxies. Lens modeling of Hubble imaging also reveals a diffuse asymmetric component of significant mass consistent with the spatial extent of the MgII absorption, and offset from the galaxy light profile. This study demonstrates the power of galaxy-scale gravitational lenses to not only probe the gas around galaxies, but to also independently probe the mass of the CGM due to it’s gravitational effect. Quiescent galaxies have similar amount of cool gas to star forming galaxies, yet why galaxies stop forming stars remains an open question. The authors investigate why passive galaxies remain quiescent using a gravitationally lensed background galaxy to probe the faint, diffuse cool gas around a massive quiescent galaxy, and use lensing configuration to constrain the total mass and geometry of this gas reservoir.

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 ( $$\\sim 0.1-1.2\\times 10^{11}$$ ∼0.1-1.2×1011 M⊙), with masses comparable to massive galaxies in the local Universe. We find that the oldest galaxy in our sample formed $$\\sim 1.0\\times 10^{11}$$ ∼1.0×1011 M⊙ 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.

We describe a new approach to obtaining very high surface densities of optical spectra in astronomical observations with extremely accurate subtraction of night sky emission. The observing technique requires that the telescope is nodded rapidly between targets and adjacent sky positions; object and sky spectra are recorded on adjacent regions of a low‐noise CCD through charge shuffling. This permits the use of extremely high densities of small slit apertures (“microslits”) since an extended slit is not required for sky interpolation. The overall multiobject advantage of this technique is as large as 2.9 times that of conventional multislit observing for an instrument configuration which has an underfilled CCD detector and is always greater than 1.5 for high target densities. The “nod‐shuffle” technique has been practically implemented at the Anglo‐Australian Telescope as the “LDSS++ project” and achieves sky subtraction accuracies as good as 0.04%, with even better performance possible. This is a factor of 10 better than is routinely achieved with long slits. LDSS++ has been used in various observational modes, which we describe, and for a wide variety of astronomical projects. The nod‐shuffle approach should be of great benefit to most spectroscopic (e.g., long slit, fiber, integral field) methods and would allow much deeper spectroscopy on very large telescopes (10 m or greater) than is currently possible. Finally, we discuss the prospects of using nod‐shuffle to pursue extremely long spectroscopic exposures (many days) and of mimicking nod‐shuffle observations with infrared arrays.

The formation of galaxies by gradual hierarchical co-assembly of baryons and cold dark matter halos is a fundamental paradigm underpinning modern astrophysics 1 , 2 and predicts a strong decline in the number of massive galaxies at early cosmic times 3 – 5 . Extremely massive quiescent galaxies (stellar masses of more than 10 11   M ⊙ ) have now been observed as early as 1–2 billion years after the Big Bang 6 – 13 . These galaxies are extremely constraining on theoretical models, as they had formed 300–500 Myr earlier, and only some models can form massive galaxies this early 12 , 14 . Here we report on the spectroscopic observations with the JWST of a massive quiescent galaxy ZF-UDS-7329 at redshift 3.205 ± 0.005. It has eluded deep ground-based spectroscopy 8 , it is significantly redder than is typical and its spectrum reveals features typical of much older stellar populations. Detailed modelling shows that its stellar population formed around 1.5 billion years earlier in time ( z ≈ 11) at an epoch when dark matter halos of sufficient hosting mass had not yet assembled in the standard scenario 4 , 5 . This observation may indicate the presence of undetected populations of early galaxies and the possibility of significant gaps in our understanding of early stellar populations, galaxy formation and the nature of dark matter. A massive galaxy observed with the JWST indicates that the bulk of its stars formed within the first 500 million years of the Universe.

A massive ancient galaxy with minimal star formation is observed spectroscopically at an epoch when the Universe is less than 2 billion years old, posing a challenge to theories. Galaxies prematurely aged Deep astronomical surveys have provided evidence for groups of massive, quiescent galaxies at high redshifts, but this poses a problem: theoretical models do not account for galaxies that stopped forming stars so early in the history of the Universe. Detecting such galaxies is an observational challenge owing to their negligible rest-frame ultraviolet emission and the need for extremely deep near-infrared surveys—the evidence has so far consisted entirely of coarsely sampled photometry. Karl Glazebrook et al . report spectroscopic confirmation of one of these galaxies at a redshift of 3.717, with a stellar mass of 1.7 × 10 11 solar masses. The absorption line spectrum shows no current star-formation, and the age of the galaxy is derived to be nearly half that of the Universe. The authors suggest that the galaxy formed its stars in an extreme and short starburst within the first billion years of cosmic history, implying that our picture of galaxy formation may need an update. Finding massive galaxies that stopped forming stars in the early Universe presents an observational challenge because their rest-frame ultraviolet emission is negligible and they can only be reliably identified by extremely deep near-infrared surveys. These surveys have revealed the presence of massive, quiescent early-type galaxies 1 , 2 , 3 , 4 , 5 , 6 appearing as early as redshift z  ≈ 2, an epoch three billion years after the Big Bang. Their age and formation processes have now been explained by an improved generation of galaxy-formation models 7 , 8 , 9 , in which they form rapidly at z  ≈ 3–4, consistent with the typical masses and ages derived from their observations. Deeper surveys have reported evidence for populations of massive, quiescent galaxies at even higher redshifts and earlier times, using coarsely sampled photometry. However, these early, massive, quiescent galaxies are not predicted by the latest generation of theoretical models 7 , 8 , 9 , 10 . Here we report the spectroscopic confirmation of one such galaxy at redshift z  = 3.717, with a stellar mass of 1.7 × 10 11 solar masses. We derive its age to be nearly half the age of the Universe at this redshift and the absorption line spectrum shows no current star formation. These observations demonstrate that the galaxy must have formed the majority of its stars quickly, within the first billion years of cosmic history in a short, extreme starburst. This ancestral starburst appears similar to those being found by submillimetre-wavelength surveys 11 , 12 , 13 , 14 . The early formation of such massive systems implies that our picture of early galaxy assembly requires substantial revision.