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Abstract Variability detected in galaxies is usually attributed to their active galactic nuclei (AGNs). While all AGNs are intrinsically variable, the AGN unification model predicts that Type 2 AGNs rarely vary because their engines are blocked by dust tori. Previous UV to near-IR variability studies largely support this expectation. Here, we present a variability study with the James Webb Space Telescope (JWST) that reveals a more subtle picture. Using NIRCam imaging data from three surveys over ∼140 arcmin²in the COSMOS field, we found 117 galaxies with ≥4σvariability in the F356W band across an ∼2 yr baseline. Crossmatching with existing JWST spectroscopic data, we identified five of them atz= 0.19–3.69 (F356W corresponding to rest-frameλ ≈ 0.76–2.97 μm), which were all coincidentally observed by an NIRSpec program almost contemporaneously with the last imaging epoch. One additional variable was identified atz= 0.90 using archival Keck telescope data. These six objects form our spectroscopic subsample. Interestingly, two reside in close-pair environments, while two others form a close pair themselves. Most of their light curves can hardly be explained by nuclear transients, and AGN variability is a more plausible cause. However, among these six objects (1) only one shows broad Bracket and Pfund series permitted lines (Δv > 1000 km s⁻¹) indicative of a Type 1 AGN; (2) two show narrow permitted lines (Hαand/or He Iλ10830) consistent with Type 2 AGNs, with another one likely Type 2 based on the host galaxy properties; and (3) two others, which form a pair, show no emission lines. Our results add more challenges to the unification model. 

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 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. 

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. 

Abstract We study the large-scale environments and clustering properties of 28 low-luminosity active galactic nuclei (AGNs) atz = 3.9–6 in the GOODS-N field. Our sample, identified from the JWST NIRCam Imaging and WFSS data in Complete NIRCam Grism Redshift Survey and First Reionization Epoch Spectroscopically Complete Observations surveys with either broad Hαemission lines or V-shaped continua, are compared to 782 Hαemitters (HAEs) selected from the same data. These AGNs are located in diverse large-scale environments and do not preferentially reside in denser environments compared to HAEs. Their overdensity field,δ, averaged over (15h⁻¹cMpc)³, ranges from −0.56 to 10.56, and shows no clear correlation with broad-line luminosity, black hole (BH) masses, or the AGN fraction. It suggests that >10 cMpc structures do not significantly influence BH growth. We measure the two-point cross-correlation function of AGNs with HAEs, finding a comparable amplitude to that of the HAE autocorrelation. This indicates similar bias parameters and host dark matter halo masses for AGNs and HAEs. The correlation length of field AGNs is 4.26h⁻¹cMpc and 7.66h⁻¹cMpc at 3.9 < z < 5 and 5 < z < 6, respectively. We infer a median host dark matter halo mass of $\log (M_h/M_{\odot })\approx 11.0-11.2$ and host stellar masses of $\log \left(M_{\star }/M_{\odot }\right)\approx 8.4\text{–}8.6$ by comparing with the UniverseMachinesimulation. Our clustering analysis suggests that low-luminosity AGNs at high redshift reside in normal star-forming galaxies with overmassive BHs. They represent an intrinsically distinct population from luminous quasars and could be a common phase in galaxy evolution. 

Abstract We study the luminosity function (LF) and clustering properties of 888 Hαemitters (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 ∼62 arcmin²and reachesL_Hα ∼ 10^41.2erg s⁻¹. We identify two prominent filamentary protoclusters atz ≈ 4.41 andz ≈ 5.19, hosting 98 and 144 HAEs, respectively. The observed HαLFs 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 (α ≈ −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 atz > 5 are more evolved, resembling the populations at 3.75 < z < 5. The observed star formation rate density from Hαintegrated down to 0.45M_⊙yr⁻¹, is $0.050_{-0.003}^{+0.002}{M}_{\odot }{\mathrm{yr}}^{-1}{\mathrm{Mpc}}^{-3}$ at 3.75 < z < 5 and $0.046_{-0.004}^{+0.006}{M}_{\odot }{\mathrm{yr}}^{-1}{\mathrm{Mpc}}^{-3}$ at 5 < z < 6, with protoclusters contributing about 25% and 55%, respectively. This implies a large fraction of star formation atz> 4 occurs in protoclusters. For the first time, we conduct the star formation-rate-limited three-dimensional clustering analysis atz > 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 $r_0=4.61_{-0.68}^{+1.00}{h}^{-1}\mathrm{Mpc}$ atz ≈ 4−5 and $r_0=6.23_{-1.13}^{+1.68}{h}^{-1}\mathrm{Mpc}$ atz ≈ 5−6. Comparing the observed correlation functions with the UniverseMachinesimulation, we infer the dark matter (sub-)halo masses of HAEs to be $\log (M_h/M_{\odot })=11.0-11.2$ atz ≈ 4−6, with a scatter of 0.4 dex. 

ABSTRACT We present predictions for the high-redshift halo–galaxy–supermassive black hole (SMBH) connection from the Trinity model. Matching a comprehensive compilation of galaxy (0 ≤ z ≤ 13) and SMBH data sets (0 ≤ z ≤ 6.5), Trinity finds: (1) The number of SMBHs with M• > 109 M⊙ in the observable Universe increases by five orders of magnitude from z ∼ 10 to z ∼ 2, and by another factor of ∼3 from z ∼ 2 to z = 0; (2) The M• > 109 and 1010 M⊙ SMBHs at z ∼ 6 live in haloes with ∼(2 − 3) and (3 − 5) × 1012 M⊙; (3) the newly discovered JWST AGN candidates at 7 ≲ z ≲ 11 are overmassive compared to the intrinsic SMBH mass–galaxy mass relation from Trinity, but they are still broadly consistent with Trinity predictions for flux limited AGN samples with Lauer bias. This bias favours the detection for overmassive SMBHs due to higher luminosities at a fixed Eddington ratio. However UHZ1’s M•/M* ratio is still some 1 dex higher than Trinity AGNs, indicating a discrepancy; (4) Trinity underpredicts the number densities of GN-z11 and CEERS_1019 analogues. But given the strong constraints from existing data in Trinity, the extra constraint from GN-z11 and CEERS_1019 does not significantly change trinity model results. (5) z = 6–10 quasar luminosity functions will reduce uncertainties in the trinity prediction of the z = 6–10 SMBH mass–galaxy mass relation by up to ∼0.5 dex. These luminosity functions will be available with future telescopes, such as Roman and Euclid. 

Abstract About 70 luminous quasars discovered atz> 6.5 are strongly biased toward the bright end, thus not providing a comprehensive view of quasar abundance beyond the cosmic dawn. We present the predicted results of the Roman/Rubin high-redshift quasar survey, yielding 3 times more, 2–4 mag deeper quasar samples, probing high-redshift quasars across a broad range of luminosities, especially faint quasars atL_bol∼ 10¹⁰L_⊙orM₁₄₅₀∼ −22, which are currently poorly explored. We include high-zquasars, galactic dwarfs, and low-zcompact galaxies with similar colors as quasar candidates. We create mock catalogs based on population models to evaluate selection completeness and efficiency. We utilize the classical color dropout method in thezandYbands to select primary quasar candidates, followed up with the Bayesian selection method to identify quasars. We show that overall selection completeness >80% and efficiency ∼10% at 6.5 <z< 9, with 180 quasars atz> 6.5, 20 atz> 7.5, and 2 atz> 8.5. The quasar yields depend sensitively on the assumed quasar luminosity shape and redshift evolution. Brown dwarf rejection through proper motion up to 50% can be made for stars brighter than 25 mag, low-zgalaxies dominate at fainter magnitude. Our results show that Roman/Rubin are able to discover a statistical sample of the earliest and faintest quasars in the Universe. The new valuable data sets are worth follow-up studies with JWST and Extremely Large Telescopes to determine the quasar luminosity function faint end slope and constraint the supermassive black holes growth in the early Universe. 

Abstract We present a systematic study of the environments of 25 luminous quasars atz > 6.5 from the ASPIRE program. Using JWST/NIRCam wide-field slitless spectroscopy data, we identified 487 galaxies at 5.3 ≲ z ≲ 7.0 exhibiting [Oiii] emission. Among these, 122 [Oiii] emitters lie within ∣Δv_los∣ < 1000 km s⁻¹of the quasars, corresponding to a ∼9.4-fold enhancement relative to the average galaxy density at other redshifts. Furthermore, we identified 16 [Cii]-emitting galaxies at the quasar redshifts from Atacama Large Millimeter/submillimeter Array (ALMA) mosaic observations. A cross-correlation function analysis between quasars and [Oiii]+[Cii] emitters yields a cross-correlation length of $r_0^{\mathrm{QG}}=8.68_{-0.55}^{+0.51}{h}^{-1}\mathrm{cMpc}$ and an autocorrelation of $r_0^{\mathrm{QQ}}=15.76_{-2.70}^{+2.48}{h}^{-1}\mathrm{cMpc}$ , indicating thatz ∼ 7 quasars reside in dark matter halos with $M_{\mathrm{halo}}=10^{12.27_{-0.26}^{+0.21}}{M}_{\odot }$ and have a quasar lifetime of $t_Q=10^{{7.05}_{-1.01}^{+0.95}}\mathrm{yr}$ . Notably, the number of [Oiii]-emitting galaxies at quasar redshifts varies significantly from field to field, ranging from 0 to 20, highlighting a diverse quasar environment. Remarkably, seven quasars trace significant galaxy overdensities (i.e., protoclusters), withδ_gal > 5 within a volume ofV ∼ 500 cMpc³. We also find that ∣Δv_los∣ increases rapidly toward smaller galaxy–quasar separations in protocluster fields, consistent with galaxy kinematics around extremely massive halos in cosmological simulations. By combining JWST and ALMA data, we reveal the complex and diverse environments of these early quasars, providing robust evidence that the earliest luminous quasars are effective tracers of galaxy overdensities, albeit with substantial field-to-field variation.