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.

The history of reionization reflects the cumulative injection of ionizing photons by sources and the absorption of ionizing photons by sinks. The latter process is traditionally described in terms of a "clumping factor," which encodes the average quadratic increase in the recombination rate of dense gas within the cosmic web. The recent measurement of a short mean free path of ionizing photons from stacked quasar spectra at z similar or equal to 6 has placed the importance of sinks under increased scrutiny, but its connection to the recombination rate is not immediately obvious. Here, we present analytic arguments to connect the clumping factor to the mean free path by invoking ionization equilibrium within the ionized phase of the intergalactic medium at the end of (and after) reionization. We find that the latest mean free path and hydrogen photoionization rate measurements at z = 5-6 imply a global clumping factor C approximate to 12, much higher than previous determinations from radiation-hydrodynamic simulations of the reionization process. Similar values of C are also derived when applying the same procedure to observations at 2 < z < 5. Compared to the traditional assumption of C = 3, high-redshift galaxies must produce roughly twice as many ionizing photons (approximate to 3 photons per baryon) to reionize the Universe by z similar to 6. This additional requirement on the ionizing photon budget may help to reconcile the reionization history with JWST observations that suggest a far greater output of ionizing photons by the most distant galaxy populations.

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.

Thus far, Lyman-alpha damping wings towards quasars have been used to probe the global ionization state of the foreground intergalactic medium (IGM). A new parametrization has demonstrated that the damping wing signature also carries local information about the distribution of neutral hydrogen (HI) in front of the quasar before it started shining. Leveraging a recently introduced Bayesian JAX-based Hamiltonian Monte Carlo inference framework, we derive constraints on the Lorentzian-weighted HI column density N-H I(DW), the quasar's distance r(patch) to the first neutral patch, and its lifetime t(Q) based on James Webb Space Telescope (JWST) Near Infrared Spectrograph (NIRSpec) spectra of the two z similar to 7.5 quasars J1007+2115 and J1342+0928. After folding in model-dependent topology information, we find that J1007+2115 (and J1342+0928) is most likely to reside in a < x(HI)> = 0.32(-0.23)(+0.23)(0.58(-0.23)(+0.23)) neutral IGM while shining for a remarkably short lifetime of log(10) t(Q)/yr = 4.14(-0.18)(+0.74) (an intermediate lifetime of 5.64(-0.43)(+0.25)) along a sightline with log(10) N-HI(DW) /cm(-2) = 19.70(-0.86)(+0.35) (20.24(-0.22)(+0. 25) ) and r(patch) = 28.9(-14.4)(+54.0) cMpc (10.9(-5.9)(+5.6) cMpc). In light of the potential presence of local absorbers in the foreground of J1342+0928 as has been recently suggested, we also demonstrate how the Lorentzian-weighted column density N-HI(DW) provides a natural means for quantifying their contribution to the observed damping wing signal.

The reionization of helium is thought to occur at 2.5 less than or similar to z less than or similar to 4, marking the last phase transition and final global heating event of the intergalactic medium (IGM). Since it is driven by rare quasars, helium reionization should give rise to strong temperature fluctuations in the IGM between neutral and recently ionized regions of order sigma(lnT)similar to Delta T/T=20%-50% . We introduce a novel method to search for reionization-induced temperature fluctuations in the IGM, by using the effective optical depths of the Ly alpha forest toward a large number of background quasars. Higher IGM temperatures give rise to lower effective optical depths in the Ly alpha forest, implying that temperature fluctuations will broaden the observed optical depth distribution. We measure the distributions of the effective Ly alpha forest optical depths across 71 X-Shooter spectra from the XQ-100 survey in four redshift bins, from z = 3.76 to z = 4.19, and compare them to a large-volume cosmological hydrodynamical simulation. A good agreement is found between the observations and the simulation, which does not include temperature fluctuations; therefore, we do not detect a signature of helium reionization. We then postprocess the simulations to include an increasing amount of temperature fluctuations, until the model becomes inconsistent with the observations. We obtain tight constraints on sigma(lnT)<0.29(<0.40) at 2 sigma (3 sigma) at z = 3.76 when averaging over a scale of 100 comoving Mpc, with weaker constraints for higher redshifts and smaller scales. Our constraints are the tightest to date, implying that either the IGM temperature contrast caused by helium reionization is less than similar to 30% or the process has not yet significantly started at z = 3.76.

Measurements of quasar lifetimes at high redshift indicate that the earliest billion-solar-mass supermassive black holes (SMBHs) have only been active as luminous quasars for less than a million years. Recently, extended Ly alpha nebulae around z similar to 6 quasars have revealed that these short observed lifetimes are unlikely to be a sight-line-dependent effect. However, the interpretation of Ly alpha emission is not straightforward due to its resonant nature. In this work, we use rest-frame optical emission lines, which more directly trace photoionization by the quasar, to unambiguously validate the short line-of-sight quasar lifetimes observed at early cosmic epochs. We use deep James Webb Space Telescope/NIRSpec integral field unit observations of five z similar to 6 quasars with small proximity zones to search for their extended emission line nebulae in H alpha and [O III]5007, and detect extended emission in both emission lines around four quasars in our sample. We then use the light-crossing time of these nebulae to measure quasar lifetimes along transverse sight lines. Using their H alpha nebulae, we also confirm that recombination is likely the dominant emission mechanism behind their previously detected Ly alpha nebulae. Our results confirm the existence of high-redshift quasars with extremely short lifetimes, tQ less than or similar to 105 yr, hosting billion-solar-mass black holes, indicating that rapid or obscured accretion is likely responsible for the assembly of SMBHs in the early Universe.

We aim to study the clustering of metal absorption lines and the structures that they arise in as a function of cosmic time. We focus on C IV and Si IV absorption features that are identified along a given quasar sightline. We exploit the two-point correlation function (2PCF) to investigate the clustering of these structures as a function of their separation. We utilise the E-XQR-30 data to perform a novel analysis at z>5. We also draw on literature surveys (including XQ-100) of lower redshift quasars to investigate the possible evolution of this clustering towards cosmic noon (i.e., z 2-3). We find no significant evolution with redshift when considering the separation of absorbers in velocity space. Since we are comparing data across a large interval of cosmic time, we also consider the separation between absorbers in the reference frame of physical distances. In this reference frame, we find that the amplitude of the clustering increases with cosmic time for both C IV and Si IV on the scales of <1500 physical kpc. For the first time, we assess the 2PCF of C IV and Si IV close to the epoch of reionisation utilising the absorber catalogue from the E-XQR-30 survey. We compare this with lower redshift data and find that, on small scales, the clustering of these structures grows with cosmic time. We compare these results to the clustering of galaxies in the GAEA simulations. It appears that the structures traced by C IV are broadly comparable to the galaxies from the considered simulations. The clustering is most similar to that of the galaxies with virial masses M 10^10.5 M_sun. We require tailor-made simulations to investigate the full range of factors contributing to the observed clustering. Future ground-based spectrographs will further facilitate surveys of absorbers at this epoch with increased sensitivity.

We present optical and near-infrared (NIR) spectroscopic observations for a sample of 45 quasars at 6.50] is median < SNRJ >=9.7, median < SNRH >=10.3, and median < SNRK >=11.7; demonstrating the good data quality. This work presents the largest medium-/moderate-resolution sample of quasars at z>6.5 from ground-based instruments. Despite the diversity in instrumental set-ups and spectral quality, the data set is uniformly processed and well-characterized, making it ideally suited for several scientific goals, including the study of the quasar proximity zones and damping wings, the Ly alpha forest, the intergalactic medium's metal content, as well as other properties such as the distribution of SMBH masses and Eddington ratios. Our composite spectrum is compared to others at both high and low z from the literature, showing differences in the strengths of many emission lines, probably due to differences in luminosity among the samples, but a consistent continuum slope, which proves that the same spectral features are preserved in quasars at different redshift ranges.

Context. The recently launched James Webb Space Telescope (JWST) is opening new observing windows on the distant Universe. Among JWST's instruments, the Mid Infrared Instrument (MIRI) offers the unique capability of imaging observations at wavelengths of lambda > 5 mu m. This enables unique access to the rest frame near-infrared (NIR, lambda >= 1 mu m) emission from galaxies at redshifts of z > 4 and the visual (lambda greater than or similar to 5000 & Aring;) rest frame for z > 9. We report here on the guaranteed time observations (GTO), from the MIRI European Consortium, of the Hubble Ultra Deep Field (HUDF), forming the MIRI Deep Imaging Survey (MIDIS), consisting of an on source integration time of similar to 41 hours in the MIRI/F560W (5.6 mu m) filter. The F560W filter was selected since it would produce the deepest data in terms of AB magnitudes in a given time. To our knowledge, this constitutes the longest single filter exposure obtained with JWST of an extragalactic field as of yet. Aims. The HUDF is one of the most observed extragalactic fields, with extensive multi-wavelength coverage, where (before JWST) galaxies up to z similar to 7 have been confirmed, and at z > 10 suggested, from HST photometry. We aim to characterise the galaxy population in HUDF at 5.6 mu m, enabling studies such as: the rest frame NIR morphologies for galaxies at z less than or similar to 4.6, probing mature stellar populations and emission lines in z > 6 sources, intrinsically red and dusty galaxies, and active galactic nuclei (AGNs) and their host galaxies at intermediate redshifts. Methods. We reduced the MIRI data using the official JWST pipeline, augmented by in-house custom scripts. We measured the noise characteristics of the resulting image. Galaxy photometry was obtained, and photometric redshifts were estimated for sources with available multi-wavelength photometry (and compared to spectroscopic redshifts when available). Results. Over the deepest part of our image, the 5 sigma point source limit is 28.65 mag AB (12.6 nJy), similar to 0.35 mag better than predicted by the JWST exposure time calculator. We find similar to 2500 sources, the overwhelming majority of which are distant galaxies, but we note that spurious sources likely remain at faint magnitudes due to imperfect cosmic ray rejection in the JWST pipeline. More than 500 galaxies with available spectroscopic redshifts, up to z approximate to 11, have been identified, the majority of which are at z < 6. More than 1000 galaxies have reliable photometric redshift estimates, of which similar to 25 are at 6 < z < 12. The point spread function in the F560W filter has a full width at half maximum (FWHM) of approximate to 0.2 '' (corresponding to 1.4 kpc at z = 4), allowing the NIR rest frame morphologies and stellar mass distributions to be resolved for z < 4.5. Moreover, > 100 objects with very red NIRCam vs MIRI (3.6-5.6 mu m > 1 mag) colours have been found, suggestive of dusty or old stellar populations at high redshifts. Conclusions. We conclude that MIDIS surpasses preflight expectations and that deep MIRI imaging has great potential to characterise the galaxy population from cosmic noon to dawn.

A SPectroscopic survey of bIased halos in the Reionization Era is a quasar legacy survey primarily using JWST to target a sample of 25 z > 6 quasars with NIRCam slitless spectroscopy and imaging. The first study in this series found evidence of a strong overdensity of galaxies around J0305−3150, a luminous quasar at z = 6.61, within a single NIRCam pointing obtained in JWST Cycle 1. Here we present the first results of a JWST Cycle 2 mosaic that covers 35 arcmin ^2 with NIRCam imaging/wide-field slitless spectroscopy of the same field to investigate the spatial extent of the putative protocluster. The F356W grism data target [O iii ]+H β at 5.3 < z < 7 and reveal a population of 124 line emitters down to a flux limit of 1.2 × 10 ^−18 erg s ^−1 cm ^−2 . Fifty-three of these galaxies lie at 6.5 < z < 6.8 spanning 10 cMpc on the sky, corresponding to an overdensity within a 2500 cMpc ^3 volume of 12.5 ± 2.6, anchored by the quasar. Comparing to the [O iii ] luminosity function from the Emission line galaxies and Intergalactic Gas in the Epoch of Reionization project, we find a dearth of faint [O iii ] emitters at log( L /erg s ^−1 ) < 42.3, which we suggest is consistent with either bursty star formation causing galaxies to scatter around the grism detection limit or modest suppression from quasar feedback. While we find a strong filamentary overdensity of [O iii ] emitters consistent with a protocluster, we suggest that we could be insensitive to a population of older, more massive Lyman break galaxies with weak nebular emission on scales >​​​​​​10 cMpc.

We present a detailed study of a double-peaked Ly alpha emitter, named LAE-11, found in the proximity zone of quasar J0910-0414 at z similar to 6.6 at a proper distance of d(QSO) similar to 0.3 pMpc from the quasar. We use a combination of deep photometric data from the Subaru Telescope, Hubble Space Telescope, and James Webb Space Telescope with spectroscopic data from Keck/DEIMOS, JWST/NIRCam WFSS, and JWST/NIRSpec MSA to characterise the ionising and general properties of the galaxy, as well as the quasar environment surrounding it. Apart from Ly alpha, we detect H beta, [OIII](lambda lambda 4960, 5008) doublet, and H alpha emission lines in the various spectral datasets. The presence of a double-peaked Ly alpha profile in the galaxy spectrum allows us to characterise the opening angle and lifetime of the central quasar as theta(Q) > 49.17 degrees and t(Q) > 3.8 x 10(5) years, and probe the effect of the quasar's environment on the star formation of the galaxy. LAE-11 is a fairly bright (M-UV = -19.90(-0.12)(+0.13)), blue galaxy with a UV slope of beta = -2.61(-0.08)(+0.06) and a moderate ongoing star formation rate (SFRUV = 5.55 +/- 0.65 M-circle dot yr(-1) and SFRH alpha = 12.93 +/- 1.20 M-circle dot yr(-1)). Since the galaxy is located in a quasar-ionised region, we have a unique opportunity to measure the escape fraction of Lyman continuum photons using the un-attenuated double-peaked Ly alpha emission profile and its equivalent width at such high redshift. Moreover, we employ diagnostics which do not rely on the detection of Ly alpha for comparison, and find that all tracers of ionising photon leakage agree within 1 sigma uncertainty. We measure a moderate escape of Lyman continuum photons from LAE-11 of f(esc)(LyC) = (9 - 43)%. Detections of both H alpha and H beta emission lines allow for separate measurements of the ionising photon production efficiency, resulting in log(xi(ion)/Hz erg (-1)) = 25.57(-0.12)(+0.16) and 25.63(-0.11)(+0.17) for H alpha and H beta, respectively, when using the median f(esc)(LyC). The total ionising output of LAE-11, log(f(esc)(LyC)xi(ion,H alpha)/Hz erg(-1)) = 24.25(-0.29)(+0.26), is higher than the value of 24.3 - 24.8 that is traditionally assumed to be needed to drive reionisation forward.

The advent of the James Webb Space Telescope (JWST) has opened new horizons in the study of quasar host galaxies during the reionization epoch ( z > 6). Building upon our previous initial measurements of stellar light from two quasar host galaxies at these redshifts, we now report the detection of the stellar light from the full Cycle 1 sample of 12 distant moderate-luminosity quasar ( M _1450 > −24 mag) host galaxies at z > 6 from the Hyper Suprime-Cam Subaru Strategic Program. Using JWST/NIRCam observations at 1.5 and 3.6 μ m combined with 2D image decomposition analysis, we successfully detect the host galaxies in 11 of the 12 targets, underscoring the high detection rates achievable with moderate-luminosity quasars. Based on two-band photometry and spectral energy distribution fitting, we find that our host galaxies are massive, with log M _* / M _⊙ = 9.5–11.0. The effective radii range from 0.6 to 3.2 kpc, comparable to the sizes of inactive galaxies with similar masses at z ∼ 6 as measured with imaging from COSMOS-Web. Intriguingly, the two quasar hosts with post-starburst features, which reside at the high-mass end of our sample and exhibit relatively compact morphologies, have similar size and stellar mass surface densities to quiescent galaxies at z ∼ 4–5. These findings suggest that the so-called galaxy compaction scenario is already in place at the reionization epoch, in which gas inflows during starburst phases drive centrally concentrated star formation followed by rapid quenching, bridging the structural transition of massive galaxies from relatively extended star-forming disks to compact quiescent systems.

The red damping wing from neutral hydrogen in the intergalactic medium is a smoking-gun signal of ongoing reionization. One potential contaminant of the intergalactic damping wing signal is dense gas associated with foreground galaxies, which can give rise to proximate damped Ly$\alpha$ absorbers. The Ly$\alpha$ imprint of such absorbers on background quasars is indistinguishable from the intergalactic medium within the uncertainty of the intrinsic quasar continuum, and their abundance at $z\gtrsim7$ is unknown. Here we show that the complex of low-ionization metal absorption systems recently discovered by deep JWST/NIRSpec observations in the foreground of the $z=7.54$ quasar ULAS~J1342$+$0928 can potentially reproduce the quasar's spectral profile close to rest-frame Ly$\alpha$ without invoking a substantial contribution from the intergalactic medium, but only if the absorbing gas is extremely metal-poor ($[{\rm O}/{\rm H}]\sim-3.5$). Such a low oxygen abundance has never been observed in a damped Ly$\alpha$ absorber at any redshift, but this possibility still complicates the interpretation of the spectrum. Our analysis highlights the need for deep spectroscopy of high-redshift quasars with JWST or ELT to "purify" damping wing quasar samples, an exercise which is impossible for much fainter objects like galaxies.

We combine the deepest X-ray survey from the Chandra Deep Field-South (CDF-S) `7-Ms' survey with the deepest mid-infrared (5.6μm) image from the JWST/MIRI Deep Imaging Survey (MIDIS) in the Hubble Ultra-Deep Field (HUDF) to study the infrared counterparts and point-source emission of 31 X-ray sources with a median, intrinsic, rest-frame X-ray luminosity of log_10(L_ Xc^ 0.5-7keV)=42.04±0.22 erg s^-1. The sample includes 24 AGN with a redshift range, as set by the X-ray detectability, of z ≃ 0.5-3. Through a multi-wavelength morphological decomposition, employing three separate classifications (visual, parametric and non-parametric) we separate (where present) the luminosity of the point-like AGN component from the remainder of the host-galaxy emission. The unprecedented mid-infrared sensitivity and imaging resolution of MIRI allows, in many cases, the direct characterisation of point-like (i.e. unresolved) components in the galaxies' emission. We establish a broad agreement between the three morphological classifications. At least 70

The nature of 'little red dots' and their relation to other forms of accreting supermassive black holes remain an open question. Here we report the discovery of a little red dot at z = 7.3. It is attenuated by moderate amounts of dust, A(V) = 2.79 mag, and has an intrinsic bolometric luminosity of 10(46.6) erg s(-1) and a supermassive black hole mass of 5 x 10(8) M-circle dot. Most notably, this object is embedded in an overdensity of eight nearby galaxies, allowing us to calculate a spectroscopic estimate of the clustering of galaxies around little red dots. We find a little red dot versus galaxy cross-correlation length of r(0 ) = 8 +/- 2 h(-1) cMpc, comparable to that of z approximate to 6 ultraviolet-luminous quasars. The resulting estimate of their minimum dark matter halo mass log(10)(M-halo,M-min/M-circle dot) = 12.0(-1.0)(+0.8) indicates that nearly all haloes above this mass must host actively accreting supermassive black holes at z approximate to 7, in strong contrast with the far smaller duty cycle of luminous quasars (<1%). Our results, taken at face value, motivate a picture in which supermassive black holes in little red dot phases could serve as the obscured precursors of ultraviolet-luminous quasars, which provides a natural explanation for the short ultraviolet-luminous lifetimes inferred from both quasar clustering and quasar proximity zones.

We report the discovery of 13 broad-line AGNs at z = 5 - 8 from the first 10

The Lyman-α forest of high redshift quasars is a powerful probe of the late stages of the Epoch of Reionization (EoR), particularly through the presence of Gunn-Peterson troughs. These troughs span a broad range of lengths (up to ∼ 100 Mpc), suggesting large-scale coherent structures in the intergalactic medium. We aim to gain insight into the presence, extent, and magnitude of correlations in the Lyman-α forest at 5 5.3, extending at least tens of Mpc and strongly increasing with redshift. Our results suggest a redshift-dependent correlation length, from L ≤ 26.53 (68.47) Mpc at 1-σ (2-σ) limit at z = 5.0 to L = 252.72^+272.61_-41.61 Mpc at z = 6.1. In contrast, all simulation models predict shorter correlation lengths (< 60 Mpc) and a slower redshift evolution. The presence and redshift-dependence of correlations in the Lyman-α forest on >200 Mpc scales at z=6 indicates that cosmological simulations should be larger than this scale to adequately sample the Lyman-α forest. Despite implementing a fluctuating UVB and numerous neutral islands at z<6, our fiducial SCRIPT-based simulation fails to reproduce the large-scale correlations. It may be that those ingredients are necessary, but not sufficient, to understanding the unfolding of the EoR.

The damping wing signatures in high-redshift quasars have proven instrumental in studying the epoch of reionization. With the upcoming Euclid mission set to discover many more quasars, it is crucial to explore what this new set of quasars might reveal not only about the reionization history, but also about its topology. The topology should influence the shape and variation of quasar-damping wing signals across sightlines. We use 21cmFAST to generate patchy reionization models in cosmological volumes with diverse astrophysical parameters for the ionizing sources. We examine the median and the sightline-to-sightline variation (ΔSW 68 ) for an ensemble of damping wing signals. We find that the neutral fraction x H I , quasar lifetime t q , quasar host halo mass M qso , and minimum dark-matter halo mass (that can support star formation) M min significantly impact the median signal. Parameters tied to the reionization topology, like x H I and M min , strongly affect ΔSW 68 , compared with t q . Our findings highlight that quasar damping wings are sensitive to M min , a key variable linking reionization topology, history, and feedback processes. We also explore the convergence of damping wing signals and ionized bubble sizes with box size. We present a suite of models to assess the ability of future quasar samples to constrain astrophysical model parameters and the additional systematic uncertainty on the neutral fraction incurred when fixed to a single fiducial value.

We present in this paper (Paper II of the series) a 35 arcmin ^2 JWST/NIRCam imaging and wide-field slitless spectroscopy mosaic centered on J0305–3150, a luminous quasar at z = 6.61. The F356W grism data reveal 124 [O iii ]+H β emitters at 5.3 < z < 7, 53 of which constitute a protocluster spanning (10 cMpc) ^2 across 6.5 < z < 6.8. We find no evidence of any broad-line active galactic nucleus (AGN) in individual galaxies or stacking, reporting a median H β FWHM of 585 ± 152 km s ^−1 ; however, the mass–excitation diagram and “little red dot” color and compactness criteria suggest that there are a few AGN candidates on the outskirts of the protocluster. We fit the spectral energy distributions (SEDs) of the [O iii ] emitters with Prospector and Bagpipes and find that none of the SED-derived properties (stellar mass, age, or star formation rate) correlate with proximity to the quasar. While there is no correlation between galaxy age and local galaxy density, we find modest correlations of local galaxy density with increasing stellar mass, decreasing 10–100 Myr star formation rate ratios, and decreasing nebular line equivalent widths. We further find that the protocluster galaxies are consistent with being more massive, being older, and hosting higher star formation rates than the field sample at the 3 σ level, distributed in a filamentary structure that supports inside-out formation of the protocluster. There is modest evidence that galaxy evolution proceeds differently as a function of the density of local environment within protoclusters during the epoch of reionization, and the central quasar has little effect on the galaxy properties of the surrounding structure.

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 ∼ 7.3. Galaxies in the vicinity of the quasars are selected through ground-based and JWST/NIRCam imaging and then spectroscopically confirmed with JWST/NIRSpec using the multi-shutter assembly (MSA). Over both fields, we identify 51 z>5 galaxies, of which eight are found within a Δv_LOS=±1500 kms^-1 line-of-sight velocity window from the quasars and another eight in the background. The galaxy J0252_8713, located just 7 pkpc and Δv_LOS≈ 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 measure the quasar-galaxy cross-correlation and obtain a correlation length of r_0^QG≈7.6_-1.6^+1.7 h^-1 cMpc, based on a power-law model with a fixed slope of γ_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≃7.3 quasars of log_10(M_halo, min/M_⊙)= 11.6±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, min/M_⊙) ≳ 12.3), our clustering results provide tentative evidence for a non-monotonic redshift evolution of quasar clustering properties. We further estimate a quasar duty cycle of f_duty≈0.1%, consistent with constraints from quasar proximity zones and IGM damping wings. (abridged)