We present a detailed analysis of J154506, a strongly lensed submillimetre galaxy (SMG) behind the Lupus-I molecular cloud, and a characterisation of its physical properties using a combination of new and archival data, including VLT/MUSE and FORS2 optical data. We identify two high-significance (S/N > 5) emission lines at 97.0 and 145.5 GHz, corresponding to CO(4-3) and CO(6-5), respectively, in spectral scans from the Atacama Compact Array (ACA) and the Large Millimetre Telescope (LMT), as well as the [CII] 158 μm fine-structure line at 400 GHz observed with the Atacama Pathfinder Experiment (APEX). These detections yield a spectroscopic redshift of zspec = 3.7515 ± 0.0005. We also report the detection of [CI], HCN(4-3), and two H2O+ transitions, further confirming the redshift and providing insights into the physical properties of J154506. By modelling sub-arcsecond resolution (0.75″) ALMA Band 6 and 7 continuum data in the uv-plane, we derive an average magnification factor of 6.0 ± 0.4, and our analysis reveals a relatively cold dust (38 K) in a starburst galaxy (∼ 900 M⊙ yr−1) with a high intrinsic dust mass (∼ 2.5 × 109 M⊙) and infrared (IR) luminosity (∼ 6 × 1012 L⊙). Non-local thermodynamic equilibrium radiative transfer modelling of the joint dust spectral energy distribution (SED) and CO line excitation suggests the dust continuum emission is primarily associated with relatively diffuse regions with molecular gas densities of 102−104 cm−3, rather than compact, high-pressure environments typical of extreme starbursts or active galactic nuclei (AGNs). This interpretation is supported by the close-to-unity ratio between the dust and gas kinetic temperatures, which argues against highly energetic heating mechanisms. The CO excitation ladder peaks close to CO(5-4) and is dominated by slightly denser molecular gas. Our results underscore the unique power of far-IR and submillimetre observations to both uncover and characterise scarce, strongly lensed, high-redshift galaxies, even when they are obscured by foreground molecular clouds.

We present results of a blind search for line-emitting galaxies using Atacama Large Millimeter/submillimeter Array (ALMA) Lensing Cluster Survey data. We detected seven line emitters, one of which is [C ii ] at z = 6.071, four are CO at z = 0.8–1.1, and the remaining two are possibly CO or [C i ] within photometric redshift ranges. Three of the four CO emitters are multiple images of the same galaxy. Compared to previous line-emitter searches in ALMA deep fields, our sample probes molecular gas masses ∼1 dex below the lower bound, thanks to gravitational lensing (typically μ ∼ 4, up to ∼30 in extreme cases). Most emitters are located in a region similar to normal star-forming galaxies in the star formation rate (SFR) versus molecular gas mass plane. To reduce dependence on SFR and stellar mass, we analyzed the molecular gas fraction and depletion timescale as a function of distance from the star formation main sequence. We found that most emitters broadly follow the scaling relations from previous studies, consistent within the intrinsic scatter. In addition, we serendipitously detected the CH N = 1, J = 3/2 → 1/2 Λ-doublet transition from one CO emitter at z = 1.142, representing the first detection of CH from an individual galaxy at cosmological distances through a blind survey. The CH/CO column density ratio of ∼10 ^−4 is comparable to that of local active galactic nucleus (AGN)-host galaxies, suggesting that CH traces molecular gas associated with AGN activity, possibly irradiated by X-rays.

[CII] emission is a powerful tool for studying the gas content in galaxies, especially at early stages of evolution. Given its low excitation potential, the [CII] 158 μm line is the main coolant of neutral gas in photodissociation regions and giant molecular clouds, hence a tracer of all phases of the interstellar medium. However, there is no consensus on what is the nature of the gas traced by this emission. We aim to provide insights into the physics of the [CII] emission and predictions for future observations. We used four pre-prepared simulations performed with a version of p-gadget-3, which includes the krome chemistry package. We implemented a postprocessing semi-analytical model to simulate the [CII] emission. We analysed an isolated Milky Way-mass-size galaxy, and three merger configurations: a co-rotating, counter-rotating, and perpendicular major mergers of two Milky Way-mass-size galaxies. We reproduce fundamental relations such as the [CII] luminosity and the star formation rate, L[CII]-SFR relation, in which mergers show an extra component for the [CII] emission not traced by the star formation alone. During quiescent or starburst stages, galaxies deviate from the L[CII]-SFR relation. We find that [CII] is a robust tracer of molecular gas, as well as atomic gas in both cold and warm phases on a global scale. Our results indicate that around 50 per cent of the total [CII] emission is traced by molecular gas, while 30 to 40 per cent is traced by atomic and ionised hydrogen regardless of the configuration. Our findings suggest that the nature of the [CII] emission depends strongly on the evolutionary history of galaxies, in which mergers and starbursts act as more efficient drivers of [CII] emission through collision with molecular hydrogen.

Since the launch of JWST, the sample size of reionization-era Ly alpha emitters (LAEs) has been steadily growing; yet inferences about the neutral hydrogen fraction in the intergalactic medium exhibit increasing variance at redshift z approximate to 7, possibly indicating significant field-to-field fluctuations in the progression of cosmic reionization. In this paper, we present new JWST/NIRSpec and Keck/LRIS spectra of nine LAEs in the redshift z similar to 7 protocluster LAGER-z7OD1. Measurements of Ly alpha transmission and Ly alpha velocity offset along multiple sight lines map the Ly alpha damping wing optical depth across the galaxy overdensity. In the standard context of inside-out ionization, we estimate the radii of ionized bubbles, Rimin=0.07- 0.69 Mpc (physical), based on the distance from each LAE to the first neutral patch along the sight line. The resulting 3D topology reveals three distinct subclusters where the ionized bubbles are approaching overlap. Five of the nine LAEs plausibly ionized their bubbles, where a few bursts of star formation and a modest escape fraction are sufficient. We demonstrate, however, that the actual ionized volumes are likely larger, at least Riism = 0.42-1.29 Mpc (physical), based on an empirical model for interstellar attenuation of Ly alpha. Modeling galactic attenuation of Ly alpha significantly increases the inferred intergalactic transmission (thus enlarging the ionized path length). The error bars on the reddening correction allow fully overlapping bubbles, and our results are consistent with accelerated reionization in the protocluster.

We present a detailed analysis of J154506, a strongly lensed submillimetre galaxy (SMG) behind the Lupus-I molecular cloud, and a characterisation of its physical properties using a combination of new and archival data, including VLT/MUSE and FORS2 optical data. We identify two high-significance (S/N > 5) emission lines at 97.0 and 145.5 GHz, corresponding to CO(4-3) and CO(6-5), respectively, in spectral scans from the Atacama Compact Array (ACA) and the Large Millimetre Telescope (LMT), as well as the [CII] 158 μm fine-structure line at 400 GHz observed with the Atacama Pathfinder Experiment (APEX). These detections yield a spectroscopic redshift of zspec = 3.7515 ± 0.0005. We also report the detection of [CI], HCN(4-3), and two H2O+ transitions, further confirming the redshift and providing insights into the physical properties of J154506. By modelling sub-arcsecond resolution (0.75″) ALMA Band 6 and 7 continuum data in the uv-plane, we derive an average magnification factor of 6.0 ± 0.4, and our analysis reveals a relatively cold dust (38 K) in a starburst galaxy (∼ 900 M⊙ yr−1) with a high intrinsic dust mass (∼ 2.5 × 109 M⊙) and infrared (IR) luminosity (∼ 6 × 1012 L⊙). Non-local thermodynamic equilibrium radiative transfer modelling of the joint dust spectral energy distribution (SED) and CO line excitation suggests the dust continuum emission is primarily associated with relatively diffuse regions with molecular gas densities of 102−104 cm−3, rather than compact, high-pressure environments typical of extreme starbursts or active galactic nuclei (AGNs). This interpretation is supported by the close-to-unity ratio between the dust and gas kinetic temperatures, which argues against highly energetic heating mechanisms. The CO excitation ladder peaks close to CO(5-4) and is dominated by slightly denser molecular gas. Our results underscore the unique power of far-IR and submillimetre observations to both uncover and characterise scarce, strongly lensed, high-redshift galaxies, even when they are obscured by foreground molecular clouds.

We present the first spatially resolved characterisation of the cool intragroup medium (IGrM) in a spectroscopically confirmed galaxy group at z=1.167. Using 30 independent sightlines towards the gravitationally lensed galaxy SGAS J0033+02, we combine background light from an extended gravitational arc and various sources in the field to map the distribution and kinematics of diffuse, metal-enriched gas pertaining to the group. We detect prominent MgII, FeII, CaII, and MgI absorption extending up to 62 kpc from a massive star-forming spiral galaxy and its interacting companion. Together with four other members, these form a compact group with a virial radius of 313 kpc. Down-the-barrel, blueshifted absorption indicates outflows. The distribution and two-dimensional kinematics of this gas suggest the influence of tidal stripping and star formation-driven winds. Intervening absorption across the field partly traces internal galaxy motions. A simple superposition of individual discs cannot reproduce the velocity field at large impact parameters or in counter-rotating regions, while a global IGrM halo with a rotational velocity of 130 km/s provides a good match. Beyond individual galaxy envelopes, the data are consistent with a group-scale structure that co-rotates in concert with the galaxies. Assuming dynamical equilibrium, we estimate a total (cool+warm+hot) gas mass of 1.3-2.5x10^11 Msol, with large systematic uncertainties, corresponding to approximately 50

We present deep rest-ultraviolet (UV) spectra of six luminous z=5 – 9 galaxies in the Abell-2744 field taken as part of the JWST Cycle 4 Large Program SPURS. The individual galaxy spectra show unambiguous detections of interstellar medium (ISM) metal absorption lines from low- and high-ionization states of enriched gas, which we use to probe the ISM gas porosity and kinematics. We find a striking diversity in the absorption profiles. We find low-ionization gas covering fractions ranging from 0.2 to 0.9, indicating a heterogeneous and patchy neutral ISM. The low-ionization kinematics also show a large diversity, with velocity centroid values ranging from +70 to a significantly blueshifted -140 kms^-1, while the high-ion gas shows mostly blueshifted absorption, indicating the presence of multiphase outflows. While all sources show outflow signatures in blueshifted wings, we also find that half of our sample, in particular those with the lowest stellar masses and highest sSFRs, have low-ionization velocity centroids close to systemic velocities. This is in contrast to near-ubiquitous bulk low-ionization gas outflows at lower redshifts. We suggest that this diversity of kinematics may be due to the bulk of the cold gas having low outflow velocities in the lowest mass and highest sSFR systems, potentially due to inefficient entrainment and/or an unresolved infalling component. These spectra reveal a metal-enriched ISM with complex gas geometry and kinematics, and highlight the potential of deep JWST grating spectroscopy to reveal the properties of the ISM during the reionization era.

Context. The circumgalactic medium (CGM) is a crucial interface between galaxies and their large-scale environment, regulating gas accretion and feedback processes. Yet its physical and kinematic properties within galaxy groups, where most galaxies reside, remain poorly constrained. Aims. We present the first spatially resolved characterisation of the cool intragroup medium (IGrM) in a spectroscopically confirmed galaxy group at z ≃ 1.167 using absorption-line spectroscopy along multiple sightlines. Methods. Using 30 independent sightlines towards the gravitationally lensed galaxy SGAS J003341.5+024217, we combined background light from an extended gravitational arc and various sources in the field to map the distribution and kinematics of diffuse metal-enriched gas pertaining to this group. Results. We detected prominent Mg II, Fe II, Ca II, and Mg I absorption extending up to a projected distance of 62 kpc from a massive (log M★ = 11.0 ± 0.1 M⊙) star-forming spiral and its interacting companion. Together with four other members, these form a compact group with a virial radius of 313 kpc. Down-the-barrel, blueshifted absorption indicates outflows. The distribution and two-dimensional kinematics of this gas suggest the influence of both tidal stripping and star formation-driven winds. Intervening absorption across the field partly traces internal galaxy motions. A simple superposition of individual discs cannot reproduce the velocity field at large impact parameters or in counter-rotating regions, while a global IGrM halo with a rotational velocity of ≈130 km s−1 provides a good match. Beyond individual galaxy envelopes, we find the data to be consistent with a group-scale structure that co-rotates in concert with the galaxies. Assuming dynamical equilibrium, we estimated a total (cool+warm+hot) gas mass of 1.3 − 2.5 × 1011 M⊙, with large systematic uncertainties, corresponding to roughly 50% of all baryons within one-quarter of the group’s virial radius. Conclusions. These results point to a multiphase IGrM in which cool (∼104 K) clouds are embedded within a dynamically coherent group-wide halo. The gas appears to be gravitationally bound to the group rather than reaccreting onto individual galaxies. High-redshift strong Mg II absorbers may thus trace shared metal-enriched halos shaped by galaxy interactions and feedback, with stripped and outflowing gas accumulating in the IGrM over time.

We investigate the spatial extent and structure of the [C II] line emission in a sample of 34 galaxies at z = 4 - 6 from the [C II] Resolved ISM in STar-forming galaxies with ALMA (CRISTAL) Survey. By modeling the distribution of the [C II] line emission in the interferometric visibility data directly, we derive the effective radius of [C II] line emission assuming an exponential profile. These measurements comprise not only isolated galaxies but also interacting systems that were identified thanks to the high spatial resolution of the data. The [C II] line radius ranges from 0.5 to 3.5 kpc with an average value of < R-e,R- [CII]> = 1.90 kpc. We compare the [C II] sizes with the sizes of rest-frame ultraviolet (UV) and far-infrared (FIR) continua, which were measured from the HST F160W images and ALMA Band-7 continuum images, respectively. We confirm that the [C II] line emission is more spatially extended than the continuum emission, with average size ratios of < R-e,R- [CII]/R-e,R- UV > = 2.90 and < R-e,R- [CII]/R-e,R- FIR > = 1.54, although about half of the FIR-detected sample shows a comparable spatial extent between the [C II] line and the FIR continuum emission (R-e,R- [CII] approximate to R-e,R- FIR). The residual visibility data of the best-fit model do not show statistical evidence of flux excess, indicating that the [C II] line emission in star-forming galaxies can be characterized by an extended exponential disk profile. Overall, our results suggest that the spatial extent of [C II] line emission can primarily be explained by photodissociation regions associated with star formation activity, while the contribution from diffuse neutral medium (atomic gas) and the effects of past merger events may further expand the [C II] line distributions, causing their variations among our sample. Finally, we report the negative correlation between the [C II] surface density (Sigma([CII])) and the Ly alpha equivalent width (EWLy alpha), and a possible negative correlation between R-e,R- [CII]/R-e,R- UV and EWLy alpha, which may be in line with the scenario that atomic gas component largely contributes to the extended [C II] line emission. Future three-dimensional analysis of Ly alpha and H alpha lines will shed light on the association of the extended [C II] line emission with atomic gas and outflows.

The history of gas assembly in the early galaxies is reflected in their complex kinematics. While a considerable fraction of galaxies at z ∼ 5 are consistent with rotating disks, recent studies indicate that the dominant galaxy assembly mechanism corresponds to minor and major mergers. Despite important progress, the dynamical classification of galaxies at these epochs is still severely limited by observations’ angular and spectral resolution. We present a detailed morphological and kinematic analysis of the far-infrared-bright main-sequence galaxy HZ10 (CRISTAL-22) at z = 5.65, making use of new sensitive high-resolution (≲0.3″) [C II ] 158μm ALMA and rest-frame optical JWST/NIRSpec integral field spectroscopy observations. These observations reveal a previously unresolved complex morphology and kinematics of the HZ10 system. Using position-velocity diagrams, we confirm that HZ10 is not a single massive galaxy but instead consists of at least three components in close projected separation along the east-to-west direction. We find a [C II ]-bright central component (C) separated by 1.5 kpc and 4 kpc from the east (E) and west (W) components, respectively. Our [C II ] observations resolve the HZ10-C component, and we find a velocity gradient that could be produced by either rotation or a close-in merger. We tested the rotating disk possibility using DysmalPy kinematic modeling and the PVsplit tool. Based on this, we propose the most plausible dynamical scenario for HZ10: a double merger, where the companion galaxy HZ10-W merges with the disturbed rotating disk formed by the HZ10-C and HZ10-E components. Additionally, from the comparison between ALMA [C II ] 158μm and JWST/NIRSpec data, we find that [C II ] 158μm emission closely resembles the broad [O III ] 5007Å emission both spatially and kinematically. The kinematic similarity reflects the interacting nature of the system and suggests that ionized and neutral gas phases in HZ10 are well mixed.

We present results from Atacama Large Millimeter/submillimeter Array (ALMA) spectral line-scan observations at 3 mm and 2 mm bands of three near-infrared-dark (NIR-dark) galaxies behind two massive lensing clusters MACS J0417.5-1154 and RXC J0032.1+1808. Each of these three sources is a (sub)millimeter faint (delensed S _1.2 mm < 1 mJy) triply lensed system originally discovered in the ALMA Lensing Cluster Survey. We have successfully detected CO and [C i ] emission lines and confirmed that their spectroscopic redshifts are z = 3.652, 2.391, and 2.985. By utilizing a rich multiwavelength data set, we find that the NIR-dark galaxies are located on the star formation main sequence in the intrinsic stellar mass range of log ( M _* / M _⊙ ) = 9.8–10.4, which is about 1 order of magnitude lower than that of typical submillimeter galaxies (SMGs). These NIR-dark galaxies show a variety in gas depletion times and spatial extent of dust emission. One of the three is a normal star-forming galaxy with gas depletion time consistent with a scaling relation, and its infrared surface brightness is an order of magnitude smaller than that of typical SMGs. Since this galaxy has an elongated axis ratio of ∼0.17, we argue that normal star-forming galaxies in an edge-on configuration can be heavily dust-obscured. This implies that existing deep WFC3/F160W surveys may miss a fraction of typical star-forming main-sequence galaxies due to their edge-on orientation.

We present spatially resolved dust-continuum ALMA observations from rest frame similar to 60 to similar to 600 mu m (bands 3-10) of the hyperluminous hot dust-obscured galaxy (hot DOG) WISE J224607.6-052634.9 (W2246-0526), at redshift z = 4.6. W2246-0526 is interacting with at least three companion galaxies, forming a system connected by tidal streams. We model the multiwavelength ALMA observations of the dust continuum using a modified blackbody, from which we derive the dust properties (mass, emissivity index, area of the emitting region, and temperature) in the hot DOG and in resolved structures across a region of nearly similar to 50 kpc. The peak temperature at the location of the hot DOG, similar to 110 K, is likely the consequence of heating by the central quasar. The dust temperature drops to similar to 40 K at a radius of similar to 8 kpc, suggesting that heating by the quasar beyond that distance is non-dominant. The dust in the connecting streams between the host and companion galaxies is at temperatures between 30 and 40 K, typical of starburst galaxies, suggesting it is most likely heated by recent in situ star formation. This is the first time that dust properties have been spatially resolved over several tens of kiloparsec in a galaxy system beyond Cosmic Noon; this is more than six times the scales previously probed in galaxies at these redshifts.

We present results of a blind search for line-emitting galaxies using ALMA Lensing Cluster Survey data. We detected seven line emitters, one of which is [C ii] at z = 6.071, four are CO at z = 0.8–1.1, and the remaining two are possibly CO or [C i] within photometric redshift ranges. Three of the four CO emitters are multiple images of the same galaxy. Compared to previous line-emitter searches in ALMA deep fields, our sample probes molecular gas masses ∼1 dex below the lower bound, thanks to gravitational lensing (typically μ∼ 4, up to ∼30 in extreme cases). Most emitters are located in a region similar to normal star-forming galaxies in the star formation rate (SFR) versus molecular gas mass plane. To reduce dependence on SFR and stellar mass, we analyzed the molecular gas fraction and depletion timescale as a function of distance from the star-formation main sequence. We found that most emitters broadly follow the scaling relations from previous studies, consistent within the intrinsic scatter. In addition, we serendipitously detected the CH N = 1, J = 3/2 → 1/2 Λ-doublet transition from one CO emitter at z = 1.142, representing the first detection of CH from an individual galaxy at cosmological distances through a blind survey. The CH/CO column density ratio of ∼10^-4 is comparable to that of local AGN-host galaxies, suggesting that CH traces molecular gas associated with AGN activity, possibly irradiated by X-rays.

We present a detailed kinematic study of a sample of 32 massive (9.5 <= log(M-*/M-circle dot) <= 10.9) main sequence star-forming galaxies (MS SFGs) at 4 < z < 6 from the ALMA-CRISTAL programme. The data consist of deep (up to 15 hr observing time per target), high-resolution (similar to 1 kpc) ALMA observations of [C II]158 mu m line emission. This dataset allowed us to carry out the first systematic, kiloparsec-scale (kpc-scale) characterisation of the kinematics nature of typical massive SFGs at these epochs. We find that similar to 50% of the sample are disk-like, with a number of galaxies located in systems of multiple components. Kinematic modelling reveals these main sequence disks exhibit high-velocity dispersions (sigma(0)), with a median disk velocity dispersion of similar to 70 km s(-1) and V-rot/sigma(0) similar to 2, which is consistent with dominant gravity driving. The elevated disk dispersions are in line with the predicted evolution based on Toomre theory and the extrapolated trends from z similar to 0-2.5 MS star-forming disks. The inferred dark matter (DM) mass fraction within the effective radius f(DM)(< R-e) for the disk systems decreases with the central baryonic mass surface density. This is consistent with the trend reported by kinematic studies at z less than or similar to 3; roughly half the disks display f(DM)(< R-e)less than or similar to 30%. The CRISTAL sample of massive MS SFGs provides a reference of the kinematics of a representative population and extends the view onto typical galaxies beyond previous kpc-scale studies at z less than or similar to 3.

The ALMA [CII] Resolved Ism in STar-forming gALaxies (CRISTAL) survey is a Cycle 8 ALMA Large Programme that studies the cold gas component of high-redshift galaxies. Its sub-arcsecond resolution observations are key to disentangling physical mechanisms that shape galaxies during cosmic dawn. In this paper, we explore the morphology and kinematics of the cold gas, star-forming, and stellar components in the star-forming main-sequence galaxy CRISTAL-05/HZ3, at z = 5.54. Our analysis includes 0.3" spatial resolution ( 2 kpc) ALMA observations of the [CII] line. While CRISTAL-05 was previously classified as a single source, our observations reveal that the system is a close interacting pair surrounded by an extended component of carbon-enriched gas. This is imprinted in the disturbed elongated [CII] morphology and the separation of the two components in the position-velocity diagram ( 100 km/s). The central region is composed of two components, named C05-NW and C05-SE, with the former being the dominant one. A significant fraction of the [CII] arises beyond the close pair up to 10 kpc, while the regions forming new massive stars and the stellar component seem compact (r_[CII] 4 r_UV), as traced by rest-frame UV and optical imaging obtained with the Hubble Space Telescope and the James Webb Space Telescope. Our kinematic model, using the DYSMALpy software, yields a minor contribution of dark matter of C05-NW within a radius of 2x Reff. Finally, we explore the resolved [CII]/FIR ratios as a proxy for shock-heating produced by this merger. We argue that the extended [CII] emission is mainly caused by the merger, which could not be discerned with lower-resolution observations. Our work emphasizes the need for high-resolution observations to fully characterize the dynamic stages of infant galaxies and the physical mechanisms that drive the metal enrichment of the circumgalactic medium.

There is a broad consensus from theory that stellar feedback in galaxies at high redshifts is essential to their evolution, alongside conflicting evidence in the observational literature about its prevalence and efficacy. To this end, we utilize deep, high-resolution [C II ] emission-line data taken as part of the [C II ] resolved interstellar medium (ISM) in star-forming galaxies with the Atacama Large Millimeter/submillimeter Array (CRISTAL) survey. Excluding sources with kinematic evidence for gravitational interactions, we perform a rigorous stacking analysis of the remaining 15 galaxies to search for broad emission features that are too weak to detect in the individual spectra, finding only weak evidence that a broad component is needed to explain the composite spectrum. Additionally, such evidence is mostly driven by CRISTAL-02, which is already known to exhibit strong outflows in multiple ISM phases. Interpreting modest residuals in the stack at v ∼ 300 km s −1 as an outflow, we derive a mass outflow rate of M ̇ out = 26 ± 11 M ⊙ yr −1 and a cold outflow mass-loading factor of η m = 0.49 ± 0.20. This result holds for the subsample with the highest star formation rate surface density (Σ SFR > 1.93 M ⊙ yr −1 kpc −2 ), but no such broad component is present in the composite of the lower-star-formation-rate density subsample. Our results imply that the process of star-formation-driven feedback may already be in place in typical galaxies at z = 5, but on average are not strong enough to completely quench ongoing star formation.

Galaxy-scale outflows are of critical importance for galaxy formation and evolution. Dust grains are the main sites for the formation of molecules needed for star formation but are also important for the acceleration of outflows that can remove the gas reservoir critical for stellar mass growth. Using the MIRI medium-resolution integral field spectrograph aboard the James Webb Space Telescope (JWST), we detect the 3.28 μm aromatic and the 3.4 μm aliphatic hydrocarbon dust features in absorption in a redshift 4.601 hot dust-obscured galaxy, blue-shifted by ΔV=-5250^+276_-339 kms^-1 from the systemic redshift of the galaxy. The extremely high velocity of the dust indicates that the wind was accelerated by radiation pressure from the central quasar. These results pave a novel way for probing the physics of dusty outflows in active galaxies at early cosmic time.

Supermassive black holes (SMBHs) imprint gravitational signatures on the matter within their sphere of influence (SoI). Nuclear gas dynamics can hence be used to accurately measure the mass of an SMBH, yet such measurements remain elusive in the early Universe. We report the first dynamical measurement of an SMBH mass at z > 2, based on high spatial resolution observations of the [C II]157.7um and CO (12-11) 216.93um emission lines that resolve the SoI in an obscured quasar at z = 4.6. The radial profile of the velocity dispersion reveals a clear Keplerian rise, requiring the presence of an approximately 6 × 10^9 M_⊙ SMBH. We propose that obscured quasarsallow tracers like [C II] to survive in the inner regions, and may be ideal targets for increasing dynamical SMBH mass estimates in the early Universe.

We report integral field spectroscopy observations with the Near-Infrared Spectrograph on board the James Webb Space Telescope, targeting the 60 kpc environment surrounding the most luminous obscured quasar known at z = 4.6. We detect ionized gas filaments on 40 kpc scales connecting a network of merging galaxies, likely to form a cluster. We find regions of low ionization consistent with large-scale shock excitation surrounding the central dust-obscured quasar, out to distances nearly 8 times the effective stellar radius of the quasar host galaxy. In the nuclear region, we find an ionized outflow driven by the quasar with velocities reaching 13,000 km s ^−1 , one of the fastest discovered to date, with an outflow rate of 2000 M _⊙ yr ^−1 and a kinetic luminosity of 6 × 10 ^46 erg s ^−1 , resulting in a coupling efficiency between the bolometric luminosity of the quasar and the outflow of 5%. The kinetic luminosity of the outflow is sufficient to power the turbulent motion of the gas on galactic and circumgalactic scales, and is likely the primary driver of the radiative shocks on interstellar medium and circumgalactic medium scales. This provides compelling evidence supporting long-standing theoretical predictions that powerful quasar outflows are a main driver in regulating the heating and accretion rate of gas onto massive central cluster galaxies.

Hot dust-obscured galaxies (hot DOGs) are a family of hyper-luminous, heavily obscured quasars. A number of studies based on the identification of companions at optical to far-infrared (FIR) wavelengths have shown that these objects reside in significantly overdense regions of the Universe. Here we present further characterisation of their environments by studying the surface density of Lyman break galaxy (LBG) candidates in the vicinity of three hot DOGs. For two of them, WISE J041010.60-091305.2 (W0410-0913) at z = 3.631 and WISE J083153.25+014010.8 (W0831+0140) at z = 3.912, we identify the candidate LBG companions using deep observations obtained with Baade/IMACS. For the third, WISE J224607.56-052634.9 (W2246-0526) at z = 4.601, we reanalyse previously published data obtained with Gemini-S/GMOS-S. We optimise the LBG photometric selection criteria at the redshift of each target using the COSMOS2020 catalog. When comparing the density of LBG candidates found in the vicinity of these hot DOGs with that in the COSMOS2020 catalog, we find overdensities of delta = 1.83 +/- 0.08 (delta ' = 7.49 +/- 0.68), delta = 4.67 +/- 0.21 (delta ' = 29.17 +/- 2.21), and delta = 2.36 +/- 0.25 (delta ' = 11.60 +/- 1.96) around W0410-0913, W0831+0140, and W2246-0526, respectively, without (with) contamination correction. Additionally, we find that the overdensities are centrally concentrated around each hot DOG. Our analysis also reveals that the overdensity of the fields surrounding W0410-0913 and W0831+0140 declines steeply beyond physical scales of similar to 2 Mpc. If these overdensities evolve into clusters by z = 0, the present results suggest that the hot DOG may correspond to the early formation stages of the brightest cluster galaxy. We were unable to determine whether or not this is also the case for W2246-0526 due to the smaller field of view (FOV) of the GMOS-S observations. Our results imply that hot DOGs may be excellent tracers of protoclusters.