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Abstract We present the first results from a program searching for extended Lyαhalos around high-redshift (z ≳ 6.5) quasars using the red channel of the Keck Cosmic Web Imager (KCWI). Our observations reveal a Lyαhalo extending to ≃11 pkpc around thez= 6.64 broad absorption line quasar J0910−0414. The Lyαvelocity field displays a rotation-like gradient, and the gas velocity dispersion is consistent with gravitationally dominated motion (σ_Lyα < 300 km s⁻¹). Comparison with the [Cii] kinematics of the host galaxy core from Atacama Large Millimeter/submillimeter Array observations shows that the Lyα-emitting gas extends over a much larger region, shows distinct kinematics, and has a smaller velocity dispersion (σ_Lyα ≃ 0.6σ_{[C II]}). The Lyαspectral region of the quasar is largely obscured by a deep Nvabsorption trough, and as a result, roughly 55% of the total Lyαflux is from the extended halo. These observations demonstrate the potential of KCWI for probing the cool gas reservoir that fuels the growth of quasars and their hosts in the epoch of reionization. 

Abstract In this work, we present deep NIRSpec/PRISM and NIRSpec/G395M observations of J0910M0414-BHAE-1, a broad-line active galactic nucleus atz = 4.910 ± 0.003 initially discovered with NIRCam/WFSS. We detect rest-frame UV (e.g., Lyα, C iv, C iii], Mg ii) and optical (Hγ, Hβ, Hα, and [O iii]) lines. By modeling the Hαline, we measure FWHM = 3351 ± 66 km s⁻¹, implying a supermassive black hole with $\log (M_{\mathrm{BH}}/M_{\odot })=8.14\pm 0.02$ . The bolometric luminosity (from the broad Hα) is (2.23 ± 0.09) × 10⁴⁵ erg s⁻¹with an Eddington ratio of 0.11 ± 0.01. The errors do not include the ∼0.3–0.5 dex systematic uncertainty of the single-epoch virial method. Comparing the object’s spectral energy distribution to those of quasars and Little Red Dots suggests that the object bridges the gap between these classes. 

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 atz = 7.0 and J1007+2115 atz = 7.5, which enable the first constraints on quasar–galaxy clustering atz ≃ 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 51z > 5 galaxies, of which eight are found within a Δv_LOS= ± 1500 km s⁻¹line-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⁻¹from 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 ofr₀^QG≈ 7.6^+1.7_−1.6h⁻¹cMpc, based on a power-law model with a fixed slope ofγ_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 forz ≃ 7.3 quasars of log₁₀(M_halo,min/M_⊙) = 11.6^+0.6_−0.7in a halo model framework. Compared to measurements from EIGER at ⟨z⟩ = 6.25 and ASPIRE at ⟨z⟩ = 6.7 (where log₁₀(M_halo, min/M_⊙)≳12.1), our clustering results provide tentative evidence for a nonmonotonic redshift evolution of quasar clustering properties. We further estimate a quasar duty cycle off_duty ≈ 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. 

Abstract Variability is a fundamental signature for active galactic nuclei (AGN) activity and serves as an unbiased indicator for rapid instability happening near the center of supermassive black holes (SMBHs). Previous studies showed that AGN variability does not have strong redshift evolution, and scales with their bolometric luminosity and BH mass, making it a powerful probe to identify low-mass, low-luminosity AGNs at high redshift. JWST has discovered a new population of high-redshift galaxies likely hosting moderate accreting BHs (>10⁶M_⊙)—the little red dots (LRDs;z ∼ 4–10). In this Letter, we study the variability of a sample of 22 LRDs with V-shaped spectral energy distributions in three JWST deep fields that also have reliable Hubble Space Telescope observations in closely paired filters at 1–2μm (rest-frame UV), with the time difference between 6 and 11 yr. This LRD sample covers a redshift range of 3 < z < 8 with −21.3 < M_UV < −18.4. Based on both photometry and imaging difference analyses, we find a mean magnitude difference of ∼0.15 ± 0.26 mag, with none of the LRDs showing photometric variability at 3σsignificance. Extrapolation of Sloan Digital Sky Survey quasar variability predicts a magnitude change of order 0.3 mag for our LRD sample. This suggests an upper limit of about ∼30% AGN contribution to the total observed UV light in our sample of LRDs. 

Abstract We present new Chandra observations of seven luminous quasars atz> 6.5. Combined with archival Chandra observations of all other known quasars, they form nearly complete X-ray observations of all currently knownz∼ 7 quasars withM₁₄₅₀< –26.5, except for J0313−1806 atz= 7.642 and J0910−0414 atz= 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 luminosityL_Xand the optical/UV-to-X-ray spectral slopeα_OX) and various quasar properties (rest-UV luminosityL_{2500 Å}, bolometric luminosityL_bol, Civblueshift, and infrared luminosityL_IR). We find mostz> 6.5 quasars follow a similarα_OX–L_{2500 Å}relation asz∼ 1–6 quasars, but also display a large scatter. We find a potential correlation betweenα_OXand the Civblueshift, 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 atz> 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 ofz> 6.5 quasars. In addition, we find there are no significant correlations between eitherL_XandL_IR, norL_bolandL_IR, suggesting no strong correlations between quasar luminosity and star formation luminosity for the most luminous quasars atz> 6.5. 

ABSTRACT 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 (H i) 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 H i column density $$N_\mathrm{H\, {\small I}}^\mathrm{DW}$$, the quasar’s distance $$r_\mathrm{patch}$$ to the first neutral patch, and its lifetime $$t_\mathrm{Q}$$ based on James Webb Space Telescope (JWST) Near Infrared Spectrograph (NIRSpec) spectra of the two $$z \sim 7.5$$ 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 $$\langle x_\mathrm{H\, {\small I}} \rangle = 0.32_{-0.20}^{+0.22}$$ ($$0.58_{-0.23}^{+0.23}$$) neutral IGM while shining for a remarkably short lifetime of $$\log _{10} t_\mathrm{Q}/\mathrm{yr}= 4.14_{-0.18}^{+0.74}$$ (an intermediate lifetime of $$5.64_{-0.43}^{+0.25}$$) along a sightline with $$\log _{10} N_\mathrm{H\, {\small I}}^\mathrm{DW}/\mathrm{cm}^{-2}= 19.70_{-0.86}^{+0.35}$$ ($$20.24_{-0.22}^{+0.25}$$) and $$r_\mathrm{patch}= 28.9_{-14.4}^{+54.0} \, \mathrm{cMpc}$$ ($$10.9_{-5.9}^{+5.6} \, \mathrm{cMpc}$$). 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 $$N_\mathrm{H\, {\small I}}^\mathrm{DW}$$ provides a natural means for quantifying their contribution to the observed damping wing signal. 

Abstract We analyze two dusty star-forming galaxies atz= 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 atz ≃ 6.5–6.8. These galaxies are identified as companions to UV-luminous quasars and robustly detected in ALMA continuum and [Cii] 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_Vup to ∼7.5 mag), and thus we refer to them as “NIRCam-dark” starburst galaxies (star formation rate ≃80–250M_⊙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 atz ≳ 4 and descendants of UV-luminous galaxies atz > 10. Although it is hard to constrain their number density from a quasar survey, we conclude that NIRCam-dark galaxies can be as abundant asn ∼ 10^−5.5Mpc⁻³assuming a light halo occupation model. If true, this would equal to ∼30% of the number densities of both the quiescent galaxies atz ≳ 4 and UV-luminous galaxies atz > 10. We further predict that analogs atz ∼ 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 atz ≳ 8, wide-field JWST/NIRCam imaging and slitless spectroscopic surveys of early protoclusters are essential. 

Abstract 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 atz = 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⁻¹and a supermassive black hole mass of 5 × 10⁸ M_⊙. 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 ofr₀ = 8 ± 2 h⁻¹ cMpc, comparable to that ofz ≈ 6 ultraviolet-luminous quasars. The resulting estimate of their minimum dark matter halo mass$$\log_{10}({M}_{{\rm{halo}},\min }/{{{M}}}_{\odot })=12.{0}_{-1.0}^{+0.8}$$ ${\log }_{10}\left(M_{\mathrm{halo},\min }/M_{\odot }\right)=12.0_{-1.0}^{+0.8}$ indicates that nearly all haloes above this mass must host actively accreting supermassive black holes atz ≈ 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. 

ABSTRACT The fraction of ‘dark pixels’ in the Ly$$\alpha$$ and other Lyman-series forests at $$z\sim 5$$–6 provides a powerful constraint on the end of the reionization process. Any spectral region showing transmission must be highly ionized, while dark regions could be ionized or neutral, thus the dark pixel fraction provides a (nearly) model independent upper limit to the volume-filling fraction of the neutral intergalactic medium, modulo choices in binning scale and dark pixel definition. Here, we provide updated measurements of the 3.3 comoving Mpc dark pixel fraction at $z=4.85$–6.25 in the Ly$$\alpha$$, Ly$$\beta$$, and Ly$$\gamma$$ forests of 34 deep $$5.8 \lesssim z\lesssim 6.6$$ quasar spectra from the (enlarged) XQR−30 sample. Using the negative pixel method to measure the dark pixel fraction, we derive fiducial $$1\sigma$$ upper limits on the volume-average neutral hydrogen fraction of $$\langle x_{\rm HI} \rangle \le \lbrace 0.030+0.048,0.095+0.037,0.191+0.056,0.199+0.087\rbrace$$ at $$\bar{z}=\lbrace 5.481,5.654,5.831,6.043\rbrace$$ from the optimally sensitive combination of the Ly$$\beta$$ and Ly$$\gamma$$ forests. We further demonstrate an alternative method that treats the forest flux as a mixture of dark and transparent regions, where the latter are modelled using a physically motivated parametric form for the intrinsic opacity distribution. The resulting model-dependent upper limits on $$\langle x_{\rm HI} \rangle$$ are similar to those derived from our fiducial model-independent analysis. We confirm that the bulk of reionization must be finished at $z>6$, while leaving room for an extended ‘soft landing’ to the reionization history down to $$z\sim 5.4$$ suggested by Ly$$\alpha$$ forest opacity fluctuations. 

We present a catalogue of spectroscopically selected [O III]+Hβemitters at 6.75 < z < 9.05 and the resulting [O III] 5008 Å luminosity function (LF) in the COSMOS field. We leveraged the 0.33 deg²covered by COSMOS-3D using NIRCam/WFSS F444W to perform the largest spectroscopic search for [O III] emitters at 6.75 < z < 9.05. We present our catalogue of 249 [O III] emitters and their associated completeness function. The inferred constraints on the [O III] LF enabled us to characterise the knee of the [O III] 5008 Å LF, resulting in improved [O III] 5008 Å LF constraints atz ∼ 7, 8. Notably, we find evidence for a decline of the [O III] luminosity density betweenz ∼ 6 − 8, which could be expected if the metallicity of [O III] emitters, as well as the cosmic star-formation rate density, is declining at these redshifts. We find that theoretical models that reproduce thez ∼ 7, 8 [O III] 5008 Å LF do not reproduce well the [O III] equivalent width distribution, pointing to potential challenges in the modelling of [O III] and other nebular lines in the early Universe. Finally, we provide the first constraints on the cosmic variance of [O III] emitters, estimating at 15% the fractional uncertainty for thez ∼ 7, 8 [O III] 5008 Å LF in the 0.33 deg²field. This estimate is in good agreement with that inferred from clustering, and it shows that the [O III] 5008 Å LF derived from smaller extragalactic legacy fields is strongly affected by cosmic variance. Our results highlight the fundamental role that wide-area JWST slitless surveys play to map the galaxy large-scale structure down into the reionisation era, serving as a springboard for a variety of science cases.