Weekly issue

Week 30, 2026

Jul 20–26, 2026

Week 30, 2026 includes 6 curated papers, centered on spectroscopy, LRD, QSO.

2607.19491v1

Rapid growth in a dual AGN during a gas-rich merger at z~4.5

Hyewon Suh, Roberto Decarli, Emanuele Paolo Farina, Julia Scharwächter, Mar Mezcua, Giorgio Lanzuisi, Federica Loiacono, Brian C. Lemaux, Sukyoung K. Yi, Stefano Marchesi, Marta Volonteri, Günther Hasinger, Francesca Civano, Anniek Gloudemans, Ena Choi, Yeonwoo Nam, Adi Foord, Silvia Onorato

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Suh et al. report LID-1166, a heavily obscured, X-ray-selected dual AGN at z~4.5 whose two nuclei are separated by just ~1.5 kpc, making it the first confirmed sub-3-kpc dual AGN beyond the local Universe. JWST/NIRSpec IFU data resolve distinct narrow Hα components offset by ~-164 km/s and detect broad Hα from both nuclei, while ALMA [CII] independently finds matched spatial and kinematic cold-gas components, establishing a gas-rich late-stage merger rather than a lensed single source. Broad-line mass estimates of log(MBH/M⊙)~7.8 and 7.2, together with a system-integrated Eddington ratio of 3.7, identify rapid super-Eddington growth in a phase that may help place massive black holes on the local black-hole–host relation early and expose a missing population of obscured merger-driven dual AGN.

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2607.19057v1

An (in)complete NIRSpec census of Balmer absorption in Type 1 AGN -- radiation-driven outflows in little red dots, quasars and variable stars

Ignas Juodžbalis, Xihan Ji, Francesco D'Eugenio, Jan Scholtz, Roberto Maiolino, Amanda Stoffers, Alessandro Marconi, Elena Bertola, Andrew J. Bunker, Stefano Carniani, Giovanni Cresci, Emma Curtis-Lake, Zheng Ma, Cosimo Marconcini, Eleonora Parlanti, Pierluigi Rinaldi, Brant Robertson, Hannah Übler, Giacomo Venturi, Junyu Zhang

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Using archival JWST/NIRSpec R1000 and R2700 spectroscopy, this paper builds a completeness-aware census of broad Hα Balmer absorption in 47 Type-1 AGN, separating Little Red Dots (LRDs) from Little Blue Dots (LBDs). Absorbers are confined to the LRD region of the UV-optical slope selection, while the completeness-corrected incidence in LBDs is consistent with only an upper limit. The authors find that Balmer-absorption velocity correlates significantly with narrow [O III] λ5007 luminosity and argue, from comparisons with FeLoBAL quasars and stellar Hα absorbers, that LRD absorption traces radiatively driven outflows. A central observational caveat is that R1000 spectra are strongly resolution-limited for recovering absorption widths and optical depths, making R2700 data essential for more reliable physical constraints.

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Key figures to inspect

Figure 1. This selection diagram establishes the population-level result that every identified Balmer absorber occupies the LRD region rather than the LBD region, making the LRD-LBD distinction immediately visible.
Figure 3. The completeness maps show why instrumental resolution is central to the census: R1000 performs substantially worse than R2700 for recovering narrow absorption features, directly motivating the paper's incompleteness corrections and measurement caveat.
Figure 5. This is the key demographic synthesis, comparing the inferred Balmer-absorption incidence across the LRD and LBD samples with BAL and FeLoBAL quasars while clearly displaying the LBD constraint as an upper limit.
Figure 8. This comparison places LRDs on the luminosity-column-density sequence of FeLoBALs, showing that they extend the BAL population toward lower luminosities and higher columns rather than forming an unrelated absorber class.
Figure 15. This cross-scale velocity versus broad-Hα-luminosity comparison provides the paper's clearest physical synthesis, linking LRDs and FeLoBALs along an AGN sequence while contrasting them with NGC 4151 and luminous blue variable stars.

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2607.20617v1

A dust-free hierarchically nested supermassive-star model for James Webb Space Telescope Little Red Dots

Pau Amaro Seoane

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Amaro Seoane proposes a dust-free interpretation for the dust-poor subset of JWST little red dots: a hierarchically nested supermassive-star configuration in which a radiation-dominated envelope encloses a trapped nuclear star cluster and dense secondary core. Magnetic support driven by plunging stars inflates and cools the primary envelope to produce the red optical continuum, while unobscured infalling stars supply the blue UV excess; the Compton-thick nested core both thermalizes X-rays and generates broad hydrogen-line wings. The model links these spectral and multiwavelength signatures to rapid seed growth under the host envelope's global radiation limit, potentially reducing assembly from hundreds to tens of millions of years, though it is presented as a qualitative physical framework rather than a direct fit to an LRD sample.

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Figure 1. This evolutionary timeline establishes the paper's central nested-supermassive-star sequence, from gas accumulation and stellar capture through secondary-core formation, black-hole collapse, and the proposed rapid accretion phase. It is the clearest schematic of how the individual spectral and growth arguments are intended to fit into one physical channel.
Figure 2. This is the key dust-free continuum diagnostic. The left panel shows the claimed magnetic inflation of the radiation-dominated envelope relative to an unmagnetized polytrope, while the right panel connects the cooled envelope plus unshielded cluster stars to the defining red-optical and blue-UV V-shaped LRD spectrum.
Figure 3. This figure carries the model's broad-line and X-ray-obscuration-facing physical picture through the secondary core. Its damped settling calculation and synthetic hydrogen profile illustrate how virialized debris can create broad Balmer wings while an initially expanding, unvirialized component produces a narrow absorption trough.

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2607.17448v1

Optically Thick Outflow Driven by Supercritical Accretion May Explain Little Red Dots

Jun-Rong Liu, Hua Feng, Luis C. Ho

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Liu, Feng, and Ho argue that the dense red envelope inferred around Little Red Dots can arise naturally as the photosphere of an optically thick, radiation-driven outflow from supercritical black-hole accretion. Applying an analytic outflow model to 36 LRDs plus the local analogue The Egg, they find that black holes of roughly 10^5–10^7 solar masses accreting at dimensionless rates of about 1500–5000 reproduce the observed red-envelope luminosities and 3000–6000 K continua. A scattering region outside the photosphere then helps explain the broad Balmer lines: model FWHMs agree within a factor of 1.5 for over 80% of objects, while Cloudy calculations show that partially ionized outflow gas can also yield broadly observed Balmer-break strengths. The work supplies a physically motivated origin for the otherwise phenomenological dense-envelope picture of LRDs and links their continua, line widths, and Balmer features to a single supercritical-accretion framework.

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Key figures to inspect

Figure 2. This is the primary population-level test of the proposed photospheric-outflow interpretation: the measured luminosity-temperature locus of 36 LRD envelopes and The Egg is compared directly with model tracks spanning black-hole mass and accretion rate.
Figure 3. This figure shows the key line-diagnostic result, comparing observed broad-line FWHMs with predictions that combine outflow kinematics and electron-scattering broadening. Its proximity to the one-to-one relation demonstrates why the extended scattering region is central to the model.
Figure 4. This distribution-level comparison tests whether partially ionized gas beyond the photosphere can produce the observed Balmer breaks. It connects the continuum-fitting outflow solution to a spectral feature that is especially characteristic of LRDs.
Figure 5. The Balmer-decrement distribution provides a complementary nebular diagnostic using object-by-object outflow parameters inferred from luminosity and temperature. It tests whether the same model that matches the red continuum and line widths remains broadly consistent with the hydrogen-line ratios.

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2607.17729v1

Two Peas in a Pod: The First Confirmed Dual Active Galactic Nucleus within a Green Pea Galaxy System

Konstantinos Kouroumpatzakis, Peter G. Boorman, Jiří Svoboda, Ryan Pfeifle, Abhijeet Borkar, Maitrayee Gupta, Daniel Stern, Andreas Zezas

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Kouroumpatzakis et al. identify SDSS J162209.41+352107.5 (J1622+3521) as the first confirmed dual AGN in a Green Pea system, using Chandra to resolve two hard X-ray nuclei separated by 8.4 kpc. Keck/DEIMOS spectroscopy shows that the two components share a common redshift and each independently displays broad Balmer emission, high-ionization lines including He II, [Ne V], and [Fe VII], and AGN-like narrow-line ratios. The system extends confirmed dual-AGN hosts into the compact, low-mass, intensely star-forming and low-metallicity regime, making it a nearby analogue for merger-assisted black-hole growth in rapidly assembling early galaxies. Its main significance is direct evidence that an interaction can fuel simultaneous, efficient accretion onto two SMBHs outside the massive-merger population that dominates known dual AGN.

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Key figures to inspect

Figure 1. The essential discovery image: DECaLS reveals the disturbed two-nucleus morphology and tidal structure, while Chandra spatially resolves the two X-ray sources and directly measures their 8.4 kpc projected separation.
Figure 2. Shows the decisive spatially separated Keck/DEIMOS spectra for both X-ray nuclei, establishing their common redshift and providing the optical basis for treating the pair as a physically associated dual AGN.
Figure 5. The narrow-line BPT placement demonstrates that both decomposed nuclei lie in the AGN regime, helping rule out star formation as the origin of the optical excitation in this extreme compact system.
Figure 7. Connects the extinction-corrected broad Hα and intrinsic hard X-ray luminosities of both components to an empirical AGN relation, providing a compact multiwavelength consistency check on the two accreting SMBHs.
Figure 8. Places both virial black-hole mass estimates in the black-hole-mass--stellar-mass plane alongside local AGN, broad-line Green Peas, and scaling relations, highlighting the unusual low-mass host regime reached by this dual system.

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2607.21587v1

XMM-Newton and Swift Unveil Another X-Ray Transient in NGC 4945, XMM J130514.64-493311.27

Ryan W. Pfeifle, Kimberly A. Weaver, Jenna M. Cann, Murray Brightman, Miranda McCarthy

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Pfeifle et al. report XMM J130514.64-493311.27, a newly recognized off-nuclear X-ray transient 5.5 arcmin south of the Compton-thick AGN in NGC 4945, found in the deepest 2022 XMM-Newton imaging after being absent from earlier XMM-Newton and Chandra data. Its soft X-ray spectrum (Gamma approximately 3) is well described by either a multicolor disk plus power law or multicolor disk plus thermal-plasma model, with a 0.3-10 keV luminosity of about 2.2-2.3 x 10^38 erg s^-1 and no obvious flaring during the XMM-Newton exposure. Swift-XRT detections in 2008, 2019, and 2022 trace recurrent activity, while the lack of optical through radio counterparts and a possible NEOWISE mid-IR counterpart lead the authors to identify the source as an X-ray binary caught in an active phase, underscoring the transient-rich compact-object population around this nearby obscured AGN host.

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Key figures to inspect

Figure 1. This field-level 2022 XMM-Newton image locates the new transient within NGC 4945 relative to the previously cataloged ULX and X-ray-binary population, establishing that the target is an off-nuclear source rather than nuclear AGN structure.
Figure 2. The multi-epoch XMM-Newton and stacked Chandra comparison is the clearest visual evidence for transience: the source is absent in 2001, 2004, and the 2000-2021 Chandra mosaic but prominent in 2022.
Figure 4. The favored XMM-Newton spectral fits directly support the paper's physical interpretation, showing the soft multicolor-disk-plus-power-law model and the disk-plus-thermal-plasma alternative that yield the reported X-ray-binary-like luminosity.
Figure 5. The Swift spectrum and long-baseline light curve place the 2022 XMM-Newton detection in a recurrent-outburst context, documenting detections in multiple epochs as well as intervening upper limits and the source's soft character.