Weekly issue

Week 31, 2026

Jul 27 – Aug 2, 2026

Week 31, 2026 includes 10 curated papers, centered on spectroscopy, high-z, QSO.

2607.25696v1

Tracing Obscured AGN Contribution and Number Fraction Across 0 < z < 6 with JWST

Angel Rodriguez Barbosa, Tomotsugu Goto, Daryl Joe D. Santos, Chih-Teng Ling, Tetsuya Hashimoto, Ece Kilerci, Priyanka Jalan, Terry Long Phan, Deriyan Senjaya, Vignesh V. V. Rao, Bahareh S. Salmasi

Theme match 5/5

Digest

Using 0.4–25 μm photometry from the SMILES MIRI and JADES programs in GOODS-S, the authors fit multi-wavelength SEDs with CIGALE to identify 278 obscured AGN over 0 < z < 6, a seven-fold expansion over their earlier CEERS-based sample. Both the AGN infrared contribution and AGN number fraction rise with redshift: the reported AGN fraction grows from 5% at z < 2 to roughly 30% at higher redshift, while the median AGN contribution increases by up to 0.15. In contrast, neither metric shows a fundamental dependence on total IR luminosity, arguing that the prevalence of JWST-revealed obscured accretion is primarily an epoch-dependent demographic effect rather than a simple function of host IR output.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 1. This sample-definition figure maps total IR luminosity against redshift for every galaxy and color-codes sources by their fitted AGN IR fraction. It is the essential visual context for the paper’s demographic claims, showing the redshift and luminosity coverage from which the obscured-AGN fraction and AGN-contribution trends are measured.

Tags

2607.26177v1

How to raise a supermassive black hole: interpreting early JWST AGN with the AESOPICA simulations

Sophie Koudmani, Jan Scholtz, Anthony J. Taylor, Ignas Juodžbalis, Debora Sijacki, Rachel S. Somerville, Roberto Maiolino, Emma Curtis-Lake, Steven L. Finkelstein, Martin A. Bourne, Francesco D'Eugenio, Sophia Geris, Lucy R. Ivey, Hannah Übler

Theme match 4/5

Digest

AESOPICA uses twelve 60 Mpc FABLE-based cosmological simulations, spanning 10^2–10^5 solar-mass seeds, altered accretion and super-Eddington prescriptions, and supernova feedback, then passes the outputs through the BALMERSOPICA mock JWST broad-line selection pipeline. The bulk of JWST AGN can be produced from any seed mass if early accretion is sufficiently efficient, though light seeds require the most favorable boosted, bursty growth; broad-line selection itself preferentially recovers sources that look overmassive in the black hole–stellar mass plane. The selected objects nevertheless follow the local, weakly evolving black hole–stellar velocity-dispersion relation, favoring a black-hole-first picture in which the host stellar component is still assembling, while the low-mass black hole mass function and gas metallicity retain the clearest leverage on seed formation channels.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 6. This is the core selection-effect figure: applying CEERS, JADES, and deeper mock broad-line limits produces an apparently overmassive black hole population, with heavy seeds selected as overmassive in all models and light seeds requiring SE-BoostMax growth.
Figure 7. The selected AGN fall on the local black hole mass–stellar velocity-dispersion relation despite their offset in black hole mass–stellar mass, directly illustrating the paper's central black-hole-first interpretation.
Figure 9. This figure identifies the low-mass black hole mass function as a practical seeding diagnostic, showing that heavy seeds can exceed efficient light-seed number densities by about an order of magnitude and that stacking or deeper broad-line surveys can recover this difference.
Figure 11. Gas-phase metallicity versus black hole mass and black hole-to-stellar mass ratio provides the paper's second proposed route to distinguishing seeds, while also exposing tension between the simulated parameter space and several extremely metal-poor JWST AGN hosts.

Tags

2607.26269v1

ATLAS. II. Extremely High Incidence of Balmer Line Absorption with Predominant Blueshifts in LRDs: Statistical Insights through Comparison with Type 1 AGNs

Hiroto Yanagisawa, Masami Ouchi, Tomokazu Kiyota, Makoto Ando, Yuichi Harikane, Yuta Kageura, Minami Nakane, Yoshiaki Ono, Yui Takeda

Theme match 4/5

Digest

Using archival JWST/NIRSpec medium- and high-resolution spectra plus complementary IFU data, ATLAS II searches 40 z≈2.5–7.2 little red dots with broad Hα and [O III] for Balmer absorption. Fourteen show Hα absorption, an incidence of about 35%—roughly 850 times the ≈0.04% rate in low-redshift SDSS type 1 AGNs—and a 46-absorber literature-plus-new census has substantially narrower Hα velocity offsets than the SDSS comparison. Fully 38 of 46 absorbers are blueshifted, pointing to predominantly outward-moving dense gas, while the escape/radiation-pressure analysis argues that high-column absorbers are often still bound and may either fall back toward the BLR or accelerate outward as they lose density.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 1. This figure defines the color-selected LRD parent sample and identifies which broad-Hα sources host detected Hα absorption, establishing the selection context behind the reported 14/40 incidence.
Figure 5. This is the central statistical result: it directly contrasts the Balmer-absorption fraction in the LRD sample with the exceptionally low SDSS type 1 AGN fraction and shows how the result relates to other JWST LRD censuses.
Figure 6. The compiled Hα velocity-offset distribution shows both the narrow LRD range and the strong predominance of blueshifted components in the 46-absorber census, which underpin the paper's outflow interpretation.
Figure 7. The forward-modeling test demonstrates that observational incompleteness cannot plausibly transform the broad SDSS type 1 AGN absorption-velocity distribution into the narrow distribution observed for LRDs.
Figure 11. This escape diagram connects the measured blueshifted absorbers to the radiation-pressure model, illustrating the conclusion that dense, high-column outflowing gas can remain gravitationally bound while lower-density material may escape.

Tags

2607.22835v1

Unsupervised selection and characterisation of Little Red Dots in JWST surveys with manifold learning

Michele Ginolfi, Filippo Mannucci, Alessandro Marconi, Francesco D'Eugenio, Giacomo Venturi, Francesco Belfiore, Giovanni Cresci, Caterina Bracci, Stefano Carniani, Alessandra Cozzi, Roberto Maiolino, Guido Risaliti

Theme match 4/5

Digest

Ginolfi et al. apply UMAP manifold learning to 242,000 isolated, well-measured ASTRODEEP-JWST sources using eight-band photometry, morphology, and photometric redshifts, then use spectroscopically confirmed LRDs as sparse anchors rather than imposing colour cuts. Confirmed LRDs occupy two compact loci on the manifold, primarily separated by redshift and rest-UV luminosity; the main locus achieves 0.78 purity at 0.82 completeness on the spectroscopic subset and identifies about 100 additional, generally bluer rest-optical candidates. The result provides a common, data-driven framework for comparing inconsistent LRD selections while showing that broadband colours carry most of the LRD signal, and that the same embedding can recover brown dwarfs, broad-line AGN, and photometric pathologies as distinct populations.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 2. Shows the two manifold-defined LRD anchor loci and their relation to published colour-selected samples, establishing the paper's central selection geometry without imposing an LRD colour cut.
Figure 3. Provides the quantitative completeness-purity comparison on a common parent sample, including the main and secondary loci and literature selections, making the claimed 0.78-purity and 0.82-completeness performance directly interpretable.
Figure 5. Demonstrates that the newly selected photometric candidates reproduce the characteristic V-shaped stacked SEDs of spectroscopically confirmed LRDs in both loci, supplying the key population-level validation.
Figure 10. Identifies broadband colours as the dominant carrier of the LRD signature, while morphology and photometric redshift contribute little on their own, clarifying the physical and methodological basis of the manifold localisation.

Tags

2607.22966v1

A quasar hatching from a buried red phase at z = 3.7

Zheng Ma, Yongda Zhu, Zhiyuan Ji, Eiichi Egami, Marcia J. Rieke, Xiaohui Fan, Jianwei Lyu, George H. Rieke, Fengwu Sun, Yang Sun, George D. Becker, Andrew J. Bunker, Francesco D'Eugenio, Xiangyu Jin, Ignas Juodžbalis, Weizhe Liu, Roberto Maiolino, Pierluigi Rinaldi, Feige Wang, Christopher N. A. Willmer, Yunjing Wu, Jinyi Yang, Junyu Zhang, Peixin Zhu

Theme match 3/5

Digest

Ma et al. present JADES-GS 209777 ("the Hatchling"), a z=3.711 compact red quasar caught with an unusually complete JWST-to-radio data set while its nucleus is visible but still embedded in gas and dust. Broad Hα and Hβ plus strong X-rays establish a partially exposed Type-1 AGN, while redshifted Hα and blueshifted He I absorption, disturbed O I, Mg II, Na I D, and broad blueshifted [O III] reveal dense line-of-sight gas alongside multiphase nuclear clearing. ALMA places the source in the ULIRG regime, and extended Lyα over at least 20 kpc shows that the disturbed material reaches the circumgalactic environment. The Hatchling is therefore a rare direct case for a transitional, feedback-driven emergence phase between buried red AGN and an unobscured quasar, although its unusually red UV-optical continuum may combine extreme dust attenuation, reprocessing, and BAL-like absorption rather than having a single origin.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 1. This multiwavelength overview establishes the central observational tension: a directly detected X-ray and broad-line AGN coexists with strong 1.2 mm dust emission and a sharply red UV-to-optical continuum. It is the best single figure for introducing why the Hatchling is interpreted as exposed yet still embedded.
Figure 2. The resolved Hα, Hβ, He I λ10830, O I λ8446, and [O III] profiles provide the nucleus-scale evidence for the paper's emerging-quasar interpretation. Broad Balmer emission demonstrates a visible BLR, while Balmer and He I absorption plus the blueshifted [O III] wing show that dense gas and ionized outflow remain in the immediate environment.
Figure 3. This figure extends the clearing argument beyond ionized gas: Mg II and Na I D absorption trace cool outflowing material, while the Lyα maps reveal kinematically complex emission on roughly 20 kpc scales. It is the clearest visualization of the claimed multiphase connection from the nuclear region into the host and circumgalactic medium.
Figure 4. The black-hole--host comparison places the Hatchling in an intermediate growth regime, above local scaling relations but less extreme than the most overmassive high-redshift quasars and little red dots. This population-level context supports the proposed interpretation that it is an evolutionary waypoint rather than simply a fully mature unobscured quasar.
Figure 6. The extinction-law comparison directly addresses the main continuum-shape caveat. Standard SMC, Milky Way, Calzetti, and gray AGN prescriptions do not reconstruct the full intrinsic quasar shape, whereas a small-grain model gives a closer phenomenological match, underscoring that the red continuum alone does not uniquely diagnose the obscuring physics.

Tags

2607.21719v1

Outflows in super-Eddington quasars drive clumpy circumgalactic medium and extended H$α$ nebulae at $z \gtrsim 6$

Lucas Tortora, Tiago Costa, Debora Sijacki, Jake S. Bennett

Theme match 3/5

Digest

Using zoom-in protocluster simulations with earlier black-hole seeding and mildly super-Eddington accretion, Tortora et al. follow how repeated quasar-feedback blow-outs alter the obscuration, outflowing gas, and CGM of a z~6 quasar. The super-Eddington model transitions from a compact-host, Compton-thick growth phase to an unobscured state, while metal-enriched feedback produces fast cold neutral clumps that raise the halo H I covering fraction by as much as 64% and can persist beyond the virial radius. Ray-tracing calculations predict that the cleared escape channels and restructured CGM generate more extended Hα nebulae, with size and luminosity increasing with feedback strength and declining central obscuration. The work ties early rapid SMBH growth to jointly testable signatures in quasar obscuration, neutral-gas geometry, and extended recombination-line emission.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 2. This establishes the central obscuration history by comparing hydrogen columns from the three simulations and showing how AGN-driven blow-out cycles lower the central column density. It also documents the ray-tracing treatment used to quantify the Compton-thick-to-unobscured transition.
Figure 6. This is the key physical diagnostic for the paper's cold-clump result: the super-Eddington run contains substantially more fast cold outflowing gas, linked to efficient cooling of the hot wind. Its redshift sequence connects the emerging multiphase outflow directly to the stronger cumulative feedback model.
Figure 9. This figure makes the population-level CGM consequence quantitative, relating excess DLA-level H I covering fraction within 50 kpc to cumulative quasar-mode feedback energy. It shows that strong feedback can raise the covering fraction by up to 64% by transporting dense neutral clumps into the halo.
Figure 12. This provides the clearest observational synthesis, contrasting obscured, transitional, and unobscured phases of the same super-Eddington quasar after a roughly 1 Myr illumination episode. It shows how feedback-cleared channels allow ionizing photons to reach CGM clumps and filaments, igniting extended Hα emission even when the source photon rate is lower.
Figure 13. These surface-brightness profiles translate the simulated Hα morphology into an observational diagnostic by including viewing-angle variation, dust attenuation, NIRSpec IFU sensitivity, and comparison to the BEES sample. The flattening of the profile as the quasar becomes unobscured is a concise testable prediction of the feedback-driven scenario.

Tags

2607.27329v1

An Exploratory Analysis of New Large Gaia-informed Quasar Samples in SDSS-V

Shir Aviram, Benny Trakhtenbrot, Tom Dwelly, Scott F. Anderson, Sean Morrison, Michael Eracleous, Yue Shen, Mara Salvato, Donald P. Schneider, Roberto J. Assef, Catarina Aydar, Franz E. Bauer, W. N. Brandt, Joel R. Brownstein, Johannes Buchner, Jeremy Darling, Jose G. Fernandez-Trincado, Patrick B. Hall, Dong-Woo Kim, Anton M. Koekemoer, Stephanie LaMassa, Andrea Merloni, Claudio Ricci, Qian Yang, Grisha Zeltyn

Theme match 2/5

Digest

Aviram et al. present an exploratory SDSS-V quasar census built from the Gaia- and WISE-informed GUA and Skewt_QSO target selections, yielding more than 250,000 spectroscopically confirmed quasars to z≈5 and tens of thousands of new southern-sky identifications. Both selections are exceptionally pure, exceeding 96% in the reported homogenized efficiency analysis, with M-type stars the principal contaminants. PyQSOFit spectral decompositions place the sample across Lbol≈10^44–10^48 erg s^-1, MBH≈10^6–10^10 Msun, and L/LEdd≈0.01–1; after matching for survey-depth-driven brightness differences, its inferred black-hole and accretion-property distributions agree closely with SDSS/DR16Q. The work establishes optical+IR-color and astrometric targeting as a practical route to a wide-area, high-purity southern-hemisphere quasar reference sample for future time-domain surveys.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 1. This flowchart defines the GUA and Skewt_QSO parent samples and traces how their Gaia- and WISE-informed candidate selections enter SDSS-V target cartons and the final analysis sets. It is the essential selection-function figure for interpreting the survey-scale claims.
Figure 7. The all-sky maps make the paper's hemispheric contribution immediately visible, separating the two SDSS-V selections and highlighting newly identified quasars against prior Milliquas and DESI coverage. This figure best conveys the expansion of spectroscopic quasar coverage in the southern sky.
Figure 9. The selection-efficiency comparison provides the paper's clearest quantitative headline: both GUA and Skewt_QSO attain homogenized quasar purities above 96%, with conservative lower limits also shown. It directly supports the claim that simple optical+IR and astrometric selection can deliver unusually clean large samples.
Figure 18. By matching GUA quasars to SDSS/DR16Q in brightness and redshift, this figure shows that the apparent differences in luminosity, black-hole mass, and Eddington-ratio distributions are largely selection-depth effects. It is the key diagnostic underpinning the conclusion that the SDSS-V sample is demographically consistent with earlier SDSS quasar catalogs.

Tags

2607.26255v1

Tracing the Cosmic web across Cosmic time through SKA observations of radio galaxies

Pratik Dabhade, Gianluca Castignani, Mousumi Mahato, Shishir Sankhyayan, D. J. Saikia, Viviana Casasola, Francoise Combes

Theme match 2/5

Digest

This SKA-focused chapter lays out how radio galaxies can be used as both tracers and probes of the cosmic web, linking their sizes, morphologies, spectral ageing, polarisation, and Faraday rotation to the gas and magnetic environments in which their jets propagate. It argues that SKA’s 50 MHz–15 GHz coverage, sub-microJy continuum depth, angular resolution, and dense rotation-measure grids will enable population-level measurements of jet–environment coupling from nearby filaments and clusters to high-redshift protoclusters. The central payoff is a three-dimensional, multiwavelength view of how radio-mode feedback heats and magnetises intracluster and intergalactic gas while connecting early AGN activity to protocluster assembly and star formation; angular resolution alone, however, does not guarantee morphological classification because surface brightness and imaging sensitivity remain limiting factors.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 1. Shows the redshift-dependent physical-size thresholds for resolving radio-galaxy morphology in representative SKA1 bands. It is the practical observational foundation for the chapter’s proposed use of FR structures, compact sources, and giant lobes as environmental tracers, while clearly separating angular resolvability from sensitivity and surface-brightness limitations.
Figure 2. Places FR I, FR II, and wide-angle-tail radio galaxies alongside nearby filament spines and cluster catalogues, directly visualising the chapter’s core premise that radio morphology can be interpreted within large-scale environment. Its explicitly non-homogeneous, illustrative sample is also a useful reminder that robust environmental inferences require three-dimensional, source-by-source association.
Figure 3. Uses the z=3.8 radio galaxy 4C 41.17 to connect resolved radio structure with a high-redshift protocluster-scale environment. The overlay of VLA radio contours on HST imaging provides a concrete example of the multiwavelength host identification and structural information that SKA-era surveys will extend statistically.

Tags

2607.24911v1

Vigorous turbulence driven by quasar-mode feedback in a cluster core

Satoshi Yamada, Shutaro Ueda, Hirofumi Noda, Yutaka Fujita, Misaki Mizumoto, Kentaro Nagamine, Claudio Ricci, Shoji Ogawa, Taiki Kawamuro, Shinya Yamada, Yuichi Terashima, Yoshihiro Ueda

Theme match 2/5

Digest

XRISM/Resolve spectroscopy of the z=0.297 quasar cluster H1821+643 detects Fe XXV emission from the intracluster medium broadened to a line-of-sight velocity dispersion of about 300 km s⁻¹, markedly above the relatively quiescent cores measured by Hitomi and XRISM. Spatial-spectral mixing analysis places most of this broad-line emission at projected radii of 20–100 kpc, separating it from the luminous nuclear quasar despite Resolve’s broad point-spread function. Interpreting the motions as turbulence and shear driven by a quasar-powered shock implies that roughly 1–10% of the quasar’s radiative output is coupled beyond galactic scales, bringing quasar-mode feedback into the efficiency range required in cosmological simulations.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 1. The Resolve Fe XXV spectrum provides the paper’s direct observational result: H1821+643 has a visibly broader ICM line profile than the Perseus core, establishing unusually strong turbulence or velocity shear around a radio-quiet quasar.
Figure 2. This spatial-spectral decomposition is essential for locating the signal. It shows how the authors account for PSF leakage and infer that the broad Fe-line emission predominantly arises from ICM at 20–100 kpc rather than from the quasar nucleus.
Figure 3. The comparison of non-thermal energy fraction against AGN luminosity puts H1821+643 in population context: it combines the brightest X-ray AGN with the largest inferred gas-motion energy fraction among the XRISM and Hitomi cluster sample.
Figure 4. The schematic distills the physical interpretation linking a quasar-driven wind and forward shock to enhanced 20–100 kpc ICM turbulence, and clarifies why the measured velocity dispersion implies efficient feedback beyond the host galaxy.

Tags

2607.21869v1

Stacked Reverberation Mapping of High Redshift Quasars in DESI. I. Feasibility Analysis

Rahma Alfarsy, R. E. A. Canning, Eva-Maria Mueller, Jessica Aguilar, Steven Ahlen, David Alexander, Davide Bianchi, David Brooks, Peter Clark, Todd Claybaugh, Andrei Cuceu, Tamara Davis, Axel de la Macorra, Saisrinivas Dhavala, Victoria A. Fawcett, Benjamin Floyd, Andreu Font-Ribera, Jaime Forero-Romero, Enrique Gaztañaga, Wei-Jian Guo, Gaston Gutierrez, Klaus Honscheid, Richard Joyce, Stephanie Juneau, David Kirkby, Theodore Kisner, Anthony Kremin, Claire Lamman, Martin Landriau, Laurent Le Guillou, Paul Martini, Hugh McDougall, Aaron Meisner, Ramon Miquel, John Moustakas, Seshadri Nadathur, Nathalie Palanque-Delabrouille, Zhiwei Pan, Swayamtrupta Panda, Ignasi Pérez-Ràfols, Francisco Prada, Ragadeepika Pucha, Graziano Rossi, Eusebio Sanchez, David Schlegel, Michael Schubnell, Tom Shanks, Małgorzata Siudek, David Sprayberry, Gregory Tarlé, Benjamin Alan Weaver, Hu Zou

Theme match 2/5

Digest

This feasibility study asks whether DESI’s sparse repeat spectroscopy can support stacked reverberation mapping of high-redshift quasars when paired with well-sampled ZTF continuum light curves. Mock C IV light curves spanning 1.48 < z < 5.2 show that a JAVELIN-based pipeline can recover ensemble lags within 1σ of their input values even when individual quasars have only 2–10 irregular spectroscopic epochs, because stacking turns noisy, multimodal single-object posteriors into a clear population signal. The recovered C IV radius–luminosity relation closely follows the input relation, offering a practical route to extend its calibration into the luminous, distant-quasar regime relevant for single-epoch black-hole masses and quasar cosmology. The key operational constraint is temporal leverage: a spectroscopic baseline of at least a few hundred days, comparable to the observed lag, matters more for recovery than simply adding epochs, while gains from larger stacks level off beyond roughly 450 quasars.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 4. This defines the simulated DESI C IV reverberation-mapping sample in luminosity and redshift, including the ZTF r-band limit and the population-balanced luminosity-redshift bins that underpin every stacked measurement.
Figure 13. This is the central end-to-end result: the radius–luminosity relation recovered from the DESI-like mock stacks agrees with the Hoormann et al. input C IV relation, directly supporting the paper’s proposed application.
Figure 17. This figure shows why stacking works despite unreliable individual lag posteriors: the ensemble peak strengthens as more quasars are combined, while the lag-recovery improvement plateaus beyond about 450 objects.
Figure 19. This diagnostic isolates the dominant observing requirement. Accurate stacked lags require spectroscopic observations spread over a baseline of at least several hundred days, whereas adding more spectral epochs has a weaker effect if that baseline is too short.