One of the most surprising results of early James Webb Space Telescope (JWST) observations is the discovery of an abundance of red, compact, broad-line objects dubbed "little red dots" (LRDs) at z>4. Their spatial density (∼10^-4-10^-5 cMpc^-3) is 100 times more abundant than UV-selected quasars at those redshift if one extrapolates the quasar luminosity function (QLF) down to the LRD regime. However, whether LRDs dominate black hole accretion at quasar-like luminosities (L_bol≳ 10^45-46 erg s^-1) remains unanswered, as probing the bright end of the LRD luminosity function requires a much larger area than those able to be surveyed by JWST. In this work, we present our search for the brightest LRDs (K<23.7) at 4.5<z<4.9 using wide-area multiwavelength imaging surveys from the near-UV to the infrared bands. With over 15 square degrees of sky coverage, we only identify one single LRD candidate at z_phot≈4.6, which translates into a spatial density of n(M_5100<-23.5)≈10^-8 cMpc^-3 – this is nearly 10 times less abundant than the UV-selected quasars at similar optical luminosity. When combined with the LRD sample identified by JWST at the same redshift range, we find a sharp cutoff in the optical luminosity function at λL_5100≈2.5×10^44 erg s^-1, while the QLF turnover occurs at ≳20 times higher luminosity. We therefore confirm the exclusively low-luminosity nature of LRDs, ruling out that LRDs are the counter parts of quasars. Furthermore, we speculate that, if the shape of the luminosity function holds up, it points to LRDs being powered by low-mass black holes with a narrow range of Eddington-level accretion rates.

Models predict that chemical enrichment and gas redistribution should proceed rapidly once star formation begins, yet direct observational constraints at the earliest cosmic epochs have been scarce. Here we present evidence that metal-enriched gas in multiple ionic phases was already present around galaxies before the midpoint of cosmic reionization. Using JWST/NIRSpec rest-frame ultraviolet spectroscopy of three galaxies at redshifts z=7.2-9.3, we detect blueshifted metal absorption in all three systems; across the sample, the detected transitions span neutral, low-ionization, and high-ionization species, including O I, Si II, C II, Si IV, and C IV. These absorption features show velocity offsets of order |Δv| ∼ 50–250 km s^-1, predominantly blueshifted relative to the systemic redshifts of the host galaxies derived from nebular emission lines. This ionic coexistence within a broadly shared velocity structure, together with the observed equivalent-width ratios, is consistent with outflowing or otherwise kinematically disturbed galaxy-associated gas, similar to that seen at lower redshift. The observations therefore indicate that metal-enriched gas associated with galaxies was already kinematically disturbed at very early times, requiring rapid metal production in the early generations of stars. These results show that key conditions for baryon cycling were established in at least a subset of luminous galaxies within the first several hundred million years of cosmic time, well before the completion of reionization.

Linking quasars to their dark matter environments provides critical insights into the formation and early growth of supermassive black holes (SMBHs). We present JWST observations of the environments surrounding two high-redshift quasars, J0252-0503 at z = 7.0 and J1007+2115 at z = 7.5, which enable the first constraints on quasar-galaxy clustering at z similar or equal to 7.3. Galaxies in the vicinity of the quasars were selected through ground-based and JWST/NIRCam imaging and were then spectroscopically confirmed with JWST/NIRSpec using the multi-shutter assembly (MSA). Over both fields, we identified 51 z > 5 galaxies, of which eight are found within a Delta v(LOS) = +/- 1500 km s(-1) line-of-sight velocity window from the quasars and another eight in the background. The galaxy J0252_8713, located just 7 pkpc and Delta v(LOS) approximate to 360 km s(-1) from quasar J0252-0503, emerges as a compelling candidate for one of the most distant quasar-galaxy mergers. Combining the galaxy discoveries over the two fields, we measured the quasar-galaxy cross-correlation and obtain a correlation length of r(0)(QG) approximate to 7.6(-1.6)(+1.7) h(-1) cMpc, based on a power-law model with a fixed slope of gamma(QG) = 2.0. Under the assumption that quasars and galaxies trace the same underlying dark matter density fluctuations, we infer a minimum dark matter halo mass for z similar or equal to 7.3 quasars of log(10)(M-halo,M-min/M-circle dot) = 11.6(-0.7)(+0.6) in a halo model framework. Compared to measurements from EIGER at < z > = 6.25 and ASPIRE at < z > = 6.7 (where log(10)(M-halo,M- min/M-circle dot)greater than or similar to 12.1), our clustering results provide tentative evidence for a nonmonotonic redshift evolution of quasar clustering properties. We further estimate a quasar duty cycle of f(duty) approximate to 0.05%, consistent with constraints from quasar proximity zones and intergalactic medium (IGM) damping wings. However, this implies very short phases of quasar activity, exacerbating the challenge to build billion solar mass SMBHs in only 700 Myr of cosmic time.

We present a study determining the spatial offset between the position of the supermassive black hole (as traced through their broad line regions) and the host galaxy in six z > 6 quasars. We determined the host galaxy's position from less than or similar to 0.'' 10 (less than or similar to 600 pc) resolution Atacama Large Millimeter/submillimeter Array (ALMA) [C ii] 158 mu m and corresponding dust continuum imaging. We determined the quasar's position from less than or similar to 400 pc resolution James Webb Space Telescope Near-Infrared Camera (JWST NIRCam) imaging. We estimated the observational uncertainties on the quasar's position using astrometric data from the Global Astrometric Interferometer for Astrophysics of field stars within the NIRCam images. We find that all six quasars are found within the central similar to 400 pc of their host galaxy dust continuum and [C ii] emission. Apparent offsets seen in rest-frame optical JWST observations are not detected in our ALMA data, suggesting they likely result from dust obscuration rather than a true physical separation between the SMBH and its host galaxy. Kinematic modeling of these data further reveals that none of the galaxies show evidence for recent merger activity, and most of the galaxies can be accurately modeled using a simple disk model. The lack of an offset supports theoretical models that predict that positional offset within these galaxies is either short-lived or intrinsically rare.

High-redshift ( z ≳ 6) quasars are signposts of the earliest supermassive black holes and intense star formation, offering key laboratories for black hole–galaxy evolution at cosmic dawn. While far-infrared studies have revealed large dust reservoirs and strong [C II ] emission, the physical condition and molecular gas content of their interstellar medium (ISM) remain uncertain. We present sensitive Atacama Large Millimeter/submillimeter Array Band 3 observations of the redshifted CO(7–6) and [C I ](2–1) emission lines and the underlying dust continuum in a sample of 18 quasars at z ∼ 6. We detected CO(7–6) in 15/18, [C I ](2–1) in 6/18, and continuum in 13/18 sources. Line luminosities and continuum fluxes were used to estimate molecular gas masses from CO, [C I ], and dust, and a hierarchical Bayesian cross-calibration of all four tracers yielded consistent per-source M H 2 estimates and global conversion factors. Comparison with photodissociation region (PDR) and X-ray dominated region model grids using the L [CII] / L [CI] and L CO(7–6) / L TIR ratios suggests gas densities of n > 10 4 cm −3 and radiation fields of G 0 ∼ 10 3 –10 4 for the subset of sources consistent with PDR solutions, while many quasars fall outside the model parameter space. Additional diagnostics based on the L ′ CO(7 − 6) / L ′ [CI](2 − 1) ratio indicate that a large fraction of the molecular gas resides in a warm and highly excited phase. Together these results suggest that classical PDR heating alone cannot explain the observed line ratios and that additional volumetric processes such as X-ray irradiation, turbulence and shocks, or enhanced cosmic-ray heating likely influence the excitation of the cold ISM. These results demonstrate the power of multi-line diagnostics in revealing the excitation and structure of the cold ISM in early quasar host galaxies and highlight the need for a joint analysis of CO, [C I ], [C II ], and dust emission to fully characterize star formation and heating driven by active galactic nuclei at cosmic dawn.

This paper presents the twentieth data release (DR20) from the Sloan Digital Sky Survey, the third data release of its fifth generation (SDSS-V). SDSS-V is a panoptic spectroscopy survey that is mapping the stars, gas, and galaxies through three scientific programs: the Milky Way Mapper (MWM), the Local Volume Mapper (LVM), and the Black Hole Mapper (BHM). DR20 presents the first optical (BOSS) SDSS-V spectra from southern hemisphere for the MWM and BHM surveys; new optical MWM and BHM data from the northern hemisphere are also available, for a total over 3 million spectra of 1.5 million stars and half a million galaxies and quasars, with galactic and extragalactic x-ray targets coordinate with eROSITA DR2. DR20 includes integral field spectroscopy maps from LVM of six targets and 169 tiles, spanning Galactic HII regions, planetary nebulae, and nearby galaxies. Additionally, eighteen value added catalogs are also released with DR20, based on SDSS-V MWM and BHM data, and we present a new LVM visualization tool including an RGB HiPS map as a value added product.

Photometric selection of luminous high-redshift (z≳4) quasars is plagued by contamination from numerous low-mass Galactic stars, reddened lower-redshift quasars, as well as compact luminous red galaxies. Confirmation of these rare objects thus requires extensive spectroscopic campaigns on 4 and 8-meter-class telescopes with relatively low success rates. Here we demonstrate the utility of SPHEREx spectrophotometric survey data for quasar confirmation with no ground-based follow-up required, "from the couch," applied to candidates from a purposefully simplistic photometric and astrometric Gaia+WISE selection down to low Galactic latitudes (|b|≥8^∘). Primarily from the detection of their strong broad Hα emission lines, we discover 87 new luminous 4.0 < z < 5.7 quasars with median M_1450 = -27.5, including 19 quasars at z>5, and recover 219 previously published quasars at z>4. We validate our SPHEREx selection with a 100

Environment plays a crucial role in shaping galaxy formation, yet the impact of overdensities on the internal chemical structure of galaxies at cosmic noon is still under debate. Here, we present spatially resolved gas-phase metallicity gradients for 42 star-forming galaxies in three massive protoclusters at z ∼ 2.3, derived fromHubble Space Telescope (HST) slitless grism spectroscopy from the MAMMOTH-Grism survey. We find that the majority (29 of 42, ∼69

We exploit a new sample of around 400 bright dusty galaxies from the Atacama Large Millimeter/submillimeter Array (ALMA) CHAMPS Large Program, together with the rich JWST multiband data products in the COSMOS field, to explore and validate new selection methods for identifying dusty star-forming galaxies (DSFGs). Here we present an effective empirical selection criterion based on a newly defined parameter: I-star equivalent to log(10)(M-star)xlog(10)(SFR) . Incorporating the m277W - m444W color as a second parameter further improves the purity of the selection. We then apply this method to the COSMOS2025 catalog to search for fainter dusty galaxy candidates below the ALMA CHAMPS detection limit and, through a stacking technique, identify a population of high-redshift DSFG candidates with an average flux density of S-1.2mm approximate to 150 mu Jy and a space density of similar to 6 x 10(-6) Mpc(-3). Three of these galaxies have been spectroscopically confirmed at z(spec) = 7.20, 5.85, and 5.04. This faint population seems to have been missed by most of the previous submillimeter/millimeter surveys and ground- and space-based UV-near-IR observations. We then show evidence of a possible evolutionary connection between the z > 10 UV-bright galaxies recently discovered by JWST, the faint dusty z approximate to 6-8 galaxies identified here, and the population of z approximate to 3-5 massive quiescent galaxies; all of them are potentially linked as progenitor-descendant populations based on their abundance, redshifts, and stellar masses. Future spectroscopic campaigns will be essential to confirm the redshifts and physical properties of these massive, faint, high-redshift DSFG candidates.

We present new Chandra observations of seven luminous quasars at z > 6.5. Combined with archival Chandra observations of all other known quasars, they form nearly complete X-ray observations of all currently known z ∼ 7 quasars with M _1450 < –26.5, except for J0313−1806 at z = 7.642 and J0910−0414 at z = 6.636. Together with existing ground-based near-infrared spectroscopy and Atacama Large Millimeter Array observations, we investigate the correlations between X-ray emission (the X-ray luminosity L _X and the optical/UV-to-X-ray spectral slope α _OX ) and various quasar properties (rest-UV luminosity L _2500 Å , bolometric luminosity L _bol , C iv blueshift, and infrared luminosity L _IR ). We find most z > 6.5 quasars follow a similar α _OX – L _2500 Å relation as z ∼ 1–6 quasars, but also display a large scatter. We find a potential correlation between α _OX and the C iv blueshift, suggesting a soft optical/UV-to-X-ray spectral energy distribution shape is frequently associated with fast disk winds. Furthermore, we analyze the X-ray spectrum of 11 quasars at z > 6.5 with Chandra detection, and find that the best-fit photon index, Γ, is 2.41 ± 0.27, which is likely driven by high accretion rates of z > 6.5 quasars. In addition, we find there are no significant correlations between either L _X and L _IR , nor L _bol and L _IR , suggesting no strong correlations between quasar luminosity and star formation luminosity for the most luminous quasars at z > 6.5.

Little Red Dots (LRDs) are compact active galactic nuclei (AGN) with unusual spectral energy distributions and broad Balmer emission, candidate signposts of rapid black-hole growth. We present VLT/FORS2 optical linear spectropolarimetry of the closest known LRD, SDSS J102530.29+140207.3, at z=0.1. In total light, we detect spatially extended narrow-Hα emission, probably tracing the host galaxy. We measure a nearly grey continuum polarisation p_ cont=1.53±0.04(rand.)±0.20(syst.) per cent, while broad Hα is less polarised, p_ Hα=0.58-0.84 per cent. We rule out polarisation by Milky Way dust and dilution by an unpolarised line. The polarised continuum with a depolarised line resembles local Seyfert-1 nuclei and favours a single dominant source over multi-source explanations. After Stokes-continuum subtraction, broad Hα shows no blue-to-red swing, but there is a significant (48±4)^∘ continuum-to-line offset in polarisation angle. This implies a break of axial symmetry inside this object, posing interesting geometrical challenges to all existing LRD models and frameworks. We discuss different possible origins of this symmetry break and possible paths to discriminate between them with future observations.

Luminous quasars at the redshift frontier z > 7 serve as stringent probes of super-massive black hole (SMBH) formation and they are thought to undergo much of their growth obscured by dense gas and dust in their host galaxies. Fully characterizing the symbiotic evolution of SMBHs and hosts requires rest-frame optical observations that span spatial scales from the broad-line region (BLR) to the interstellar and circumgalactic medium (ISM and CGM). The James Webb Space Telescope (JWST) now provides the necessary spatially resolved spectroscopy to do so. However, the physical conditions that regulate the interplay between SMBHs and their hosts at the highest redshifts, especially the nature of early feedback phases, remain unclear. We present JWST/NIRSpec integral field unit (IFU) observations of J0313-1806 at z = 7.64, the most distant luminous quasar known. From the rest-frame optical spectrum of the unresolved quasar, we derived a black hole mass of M-BH = (1.63 +/- 0.10)& times;10(9) M-circle dot based on H beta lambda 4861 (H beta) and an Eddington rate of lambda = L/L-Edd = 0.80 +/- 0.05, consistent with previous Mg II lambda 2800-based estimates. J0313-1806 exhibits no detectable [O III] lambda lambda 4959, 5007 emission on nuclear scales (3 sigma upper limit equivalent width of [O III] lambda 5007 < 1.42 & Aring;). Most remarkably, we did detect an ionized gas shell extending out to similar to 1.8 kpc traced by H beta emission that also lacks any significant [O III] lambda lambda 4959, 5007, with a 3 sigma upper limit on the [O III] lambda 5007 to H beta flux ratio of log(10)(F([O III])/F(H beta)) = -1.15. Through photoionization modeling, we demonstrate that the extended emission is consistent with a thin, clumpy outflowing shell where [O III] is collisionally de-excited by dense gas. We interpret this structure as a fossil remnant of a recent blowout phase, providing evidence for episodic feedback cycles in one of the earliest quasars. These findings suggest that dense ISM phases may play a crucial role in shaping the spectral properties of quasars across cosmic time.

Close quasar pairs are rare products of galaxy mergers in which both supermassive black holes (SMBHs) are actively accreting, offering strong constraints on merger-driven active galactic nuclei evolution. Identifying close quasar pairs at z greater than or similar to 4 is challenging due to the declining quasar number density in the early Universe. Here we report the confirmation of a close quasar pair at z = 5.7, J2037-4537, utilizing high-resolution Atacama Large Millimeter/submillimeter Array observations. The quasar host galaxies exhibit tidal disturbed features in both the far-infrared continuum emission and the [C ii] line emission, ruling out the doubly imaged lensed quasar scenario. The two quasar hosts are massive (M-dyn greater than or similar to 10(10)M(circle dot)) and star-forming (star formation rate greater than or similar to 500M(circle dot) yr(-1)). The confirmation of J2037-4537 puts a lower limit on the quasar pair fraction at 5.5 < z < 6, F-pair > 1.2%, which is much higher than the quasar pair fraction at z less than or similar to 4. J2037-4537 is expected to form a gravitationally bound SMBH binary within less than or similar to 2 Gyr. The elevated quasar pair fraction at z > 5.5, as indicated by J2037-4537, likely contributes to the high gravitational-wave background reported by recent pulsar timing array experiments.

We describe ongoing efforts of high-redshift transient searches using multi-epoch NIRCam imaging (F200W+F444W) and NIRSpec MSA/PRISM spectroscopy from the NEXUS JWST multi-cycle Treasury program targeting the north ecliptic pole region. The transient search area covers ∼ 61.5 arcmin^2 between the reference epoch and each subsequent NEXUS-Deep epoch at a cadence of ∼2 months. In the first year of observations from NEXUS, we detect 68 robust transients, with the host photometric redshift distribution declining rapidly at z>2 but extending to z_ phot≈ 6. In addition, we obtained secure spectroscopic redshifts for 37 transients (∼54%) from NIRSpec/PRISM and NIRCam/WFSS, with seventeen at 1 < z < 2, eight at 2 < z < 3, two at 3 < z < 4, and one tentative host association at z = 6.151. Overall, the NEXUS program recovers observed supernova (SN) rates broadly consistent with other SN search programs with JWST. While NEXUS achieves the highest transient detection efficiency, 6.6 SNe per imaging hr (2.6× COSMOS-SN and 26× JADES-SN), the limited filter coverage (F200W+F444W only) limits robust identification and classification of high-z SNe for deep spectroscopic follow-up. We describe the details of the data reduction and transient detection pipeline, and report the Year-1 transient sample along with their light curves, available MSA spectroscopy, host association, and the raw detection rate. We also describe and release a new PSF photometry package that properly accounts for correlated pixel noise from combining drizzled images.

We present COSMOS2025, the COSMOS-Web catalog of photometry, morphology, photometric redshifts, and physical parameters for more than 700 000 galaxies in the Cosmic Evolution Survey (COSMOS) field. This catalog is based on our James Webb Space Telescope 255 h COSMOS-Web program, which provides deep near-infrared imaging in four NIRCam (F115W, F150W, F277W, F444W) and one MIRI (F770W) filter over the central similar to 0.54 deg(2) (similar to 0.2 deg(2) for MIRI) in COSMOS. These data are combined with ground- and space-based data to derive photometric measurements of NIRCam-detected sources using both fixed-aperture photometry (on the space-based bands) and a profile-fitting technique on all 37 bands spanning 0.3 mu m to 8 mu m. We provide morphology for all sources from complementary techniques including profile fitting and machine-learning classification. We derive photometric redshifts, physical parameters, and non-parametric star formation histories from spectral energy distribution (SED) fitting. The catalog has been extensively validated against previous COSMOS catalogs and other surveys. Photometric redshift accuracy measured using spectroscopically confirmed galaxies out to z similar to 9 reaches sigma(MAD) = 0.012 at m(F444W) < 28 and remains at sigma(MAD) less than or similar to 0.03 as a function of magnitude, color, and galaxy type. This represents a factor of similar to 2 improvement at 26 AB mag compared to COSMOS2020. The catalog is approximately 80% complete at log(M-star/M-circle dot) similar to 9 at z similar to 10 and at log(M-star/M-circle dot) similar to 7 at z similar to 0.2, representing a gain of 1 dex compared to COSMOS2020. COSMOS2025 represents the definitive COSMOS-Web catalog. It is provided with complete documentation, together with redshift probability distributions, and it is ready for scientific exploitation today.

We study the luminosity function (LF) and clustering properties of 888 H alpha emitters (HAEs) at 3.75 < z < 6 in the GOODS-N field. The sample, built from JWST CONGRESS and FRESCO NIRCam grism surveys using a novel redshift assignment algorithm, spans similar to 62 arcmin(2) and reaches L-H alpha similar to 10(41.2) erg s(-1). We identify two prominent filamentary protoclusters at z approximate to 4.41 and z approximate to 5.19, hosting 98 and 144 HAEs, respectively. The observed H alpha LFs show similar shallow faint-end slopes for both protocluster and field galaxies at 3.75 < z < 5, and for the protocluster at 5 < z < 6 (alpha approximate to -1.2 to -1.3). In contrast, the field LF at 5 < z < 6 has a much steeper slope ( alpha=-1.87(-0.23)(+0.30)), suggesting that protocluster galaxies at z > 5 are more evolved, resembling the populations at 3.75 < z < 5. The observed star formation rate density from H alpha integrated down to 0.45 M-circle dot yr(-1), is 0.050(-0.003)(+0.002)M(circle dot)yr(-1)Mpc(-3) at 3.75 < z < 5 and 0.046(-0.004)(+0.006)M(circle dot)yr(-1)Mpc(-3) at 5 < z < 6, with protoclusters contributing about 25% and 55%, respectively. This implies a large fraction of star formation at z > 4 occurs in protoclusters. For the first time, we conduct the star formation-rate-limited three-dimensional clustering analysis at z > 4. We find that the filamentary geometry of protoclusters flattens the power-law shape of the HAE autocorrelation functions, with slopes much shallower than the typically assumed value. The autocorrelation function of field HAEs has a correlation length of r(0)=4.61(-0.68)(+1.00)h(-1)Mpc at z approximate to 4-5 and r0(=)6.23(-1.13)(+1.68)h(-1)Mpc at z approximate to 5-6. Comparing the observed correlation functions with the UniverseMachine simulation, we infer the dark matter (sub-)halo masses of HAEs to be log(M-h/M-circle dot)=11.0-11.2 at z approximate to 4-6, with a scatter of 0.4 dex.

We present one of the first measurements of the mass-metallicity relation (MZR) in multiple massive protoclusters at cosmic noon, using Hubble Space Telescope (HST) G141 slitless spectroscopy from the MAMMOTH-Grism survey. We identify 63 protocluster member galaxies across three overdense structures at z = 2-3 with robust detections of [O iii], H beta, and [O ii] emission. The sample spans gas-phase metallicities of 12+log(O/H)=8.2-8.6 , dust-corrected H beta-based star formation rates (SFRs) of 10-250 M-circle dot yr(-1), and stellar masses of M* similar to 10(9.4)-10(10.5) M-circle dot, derived via spectral energy distribution fitting using deep HST and ground-based photometry. We stack spectra in five M(*)bins to obtain average metallicities and SFRs. Relative to field galaxies at similar redshifts, protocluster members show elevated SFRs at M-* < 10(10.25) M-circle dot and a systematically shallower MZR: 12+log(O/H) =(6.96 +/- 0.13) + (0.143 +/- 0.017) xlog(M-*/M-circle dot) . We detect a mass-dependent environmental offset: massive protocluster galaxies are metal-poor compared to field counterparts of similar mass, whereas lower-mass systems exhibit comparable or mildly enhanced metallicities. This trend is consistent with a scenario where cold-mode accretion dilutes the interstellar medium (ISM) across the full mass range, while efficient recycling of feedback-driven outflows preferentially enriches the ISM in low-mass galaxies. Finally, we assess the dependence of metallicity offsets on local overdensity and find no significant trend, likely reflecting the survey's bias toward protocluster cores.

JWST observations have revealed a population of high-redshift “little red dots” (LRDs) that challenge conventional active galactic nucleus (AGN) models. We report the discovery of three local LRDs at z = 0.1–0.2, initially selected from the Sloan Digital Sky Survey database, with follow-up optical/near-IR spectroscopy and photometry. They exhibit properties fully consistent with those of high-redshift LRDs, including broad hydrogen and helium emission lines, compact morphologies, V-shaped UV-optical spectral energy distribution, declining near-IR continua, and no significant variability. Two sources were targeted but not detected in X-rays with statistical significance. All three sources show blue-shifted He i absorption, while two exhibit H α and Na D absorption lines. We detect full Balmer and Paschen line series in all three objects, along with abundant narrow [Fe ii ] emission in two. The emission-line analyses suggest narrow lines originate from AGN-powered, metal-poor regions with minimal dust; broad lines come from inner regions with exceptionally high density or atypical dust properties; and [Fe ii ] emission arises from dense gas between broad- and narrow-line regions. One of our objects, J1025+1402 (nicknamed “The Egg”), shows extremely high equivalent width Na D, K i , and Ca ii triplet absorption lines, along with other potential low-ionization absorption features, suggesting the presence of a cool (∼5000 K), metal-enriched gas envelope. The optical/near-IR continua of these LRDs are also consistent with theoretical models featuring an atmosphere around black holes (BHs). The Wide-field Infrared Survey Explorer–detected IR emission is consistent with weak dust emission of T ∼ 10 ^2 –10 ^3 K. We propose a conceptual model consisting of a largely thermalized cool-gas envelope surrounding the central BH and an extended emission-line region with high-density outflowing gas to explain the observed properties of these local LRDs.

We present JADES-GS 209777, previously cataloged as CANDELS J033238.02-274626.2, hereafter "the Hatchling," a red quasar at $z=3.711$. While the source has been reported in earlier deep-field catalogs, our multiwavelength analysis reveals a visible active nucleus still embedded in a dense gas- and dust-rich environment. Red quasar continua are often attributed to dust attenuation, including non-standard extinction curves, but the highly comprehensive multiwavelength data for this source provide direct constraints on the material being cleared. Using JWST/NIRSpec, NIRCam, MIRI, HST, MUSE, Chandra, ALMA, and VLA data, we detect broad emission lines and strong X-ray emission, showing that the active nucleus is at least partially exposed. We also detect H$α$ and He I absorption, indicating dense gas close to the nucleus. Kinematically disturbed O I, Mg II, Na D, and [O III] features, together with extended Ly$α$ emission over $\gtrsim 20$ kpc, further show that multiphase gas is being accelerated from the nuclear region into the host-galaxy environment. The ALMA detection reveals strong dust emission, with the inferred infrared luminosity placing the system in the ULIRG regime. The continuum is red and sharply declining toward the rest-frame UV, resembling compact red AGNs, and may reflect extreme dust attenuation, gas reprocessing, possible BAL-like absorption, or a combination of these effects. Regardless of which mechanism dominates the continuum shape, the line diagnostics show that the visible nucleus remains partially obscured by nearby material. The Hatchling therefore represents a unique opportunity to explore a poorly known transition phase in which feedback is likely clearing an enshrouded quasar and allowing it to emerge toward a more unobscured active nucleus.

We analyze two dusty star-forming galaxies at z = 6.6. These galaxies are selected from the ASPIRE survey, a JWST Cycle 1 medium program, and the Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 9 large program targeting 25 quasars and their environments at z similar or equal to 6.5-6.8. These galaxies are identified as companions to UV-luminous quasars and robustly detected in ALMA continuum and [C ii] emission, yet they are extraordinarily faint at the NIRCam wavelengths (down to >28.0 AB mag in the F356W band). They are more obscured than galaxies like Arp220 (A(V) up to similar to 7.5 mag), and thus we refer to them as "NIRCam-dark" starburst galaxies (star formation rate similar or equal to 80-250 M-circle dot yr(-1)). Such galaxies are typically missed by (sub)-millimeter blank-field surveys. From the star formation history (SFH), we show that the NIRCam-dark galaxies are viable progenitors of massive quiescent galaxies at z greater than or similar to 4 and descendants of UV-luminous galaxies at z > 10. Although it is hard to constrain their number density from a quasar survey, we conclude that NIRCam-dark galaxies can be as abundant as n similar to 10(-5.5) Mpc(-3) assuming a light halo occupation model. If true, this would equal to similar to 30% of the number densities of both the quiescent galaxies at z greater than or similar to 4 and UV-luminous galaxies at z > 10. We further predict that analogs at z similar to 8 should exist according to the SFH of early massive quiescent galaxies. However, they may fall below the current detection limits of wide JWST and ALMA surveys, and thus remain "JWST-dark." To fully trace the evolution of massive galaxies and dust-obscured cosmic star formation at z greater than or similar to 8, wide-field JWST/NIRCam imaging and slitless spectroscopic surveys of early protoclusters are essential.