Weekly issue

Week 27, 2026

Jun 29 – Jul 5, 2026

Week 27, 2026 includes 15 curated papers, centered on high-z, spectroscopy, LRD.

2606.30757v1

Unveil the nature of JWST-AGN and Little Red Dots with SKAO continuum surveys

Giovanni Mazzolari, Dharam V. Lal, Isabella Prandoni, Roberto Gilli, Roberto Maiolino, Hannah Übler, Ivan Delvecchio, Marcella Brusa, Marco Mignoli

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This paper lays out how SKAO continuum surveys can break the current degeneracy in the nature of JWST-selected z>4 AGN and Little Red Dots, a population now inferred to be about 1 dex more abundant than pre-JWST expectations but still largely invisible in X-rays and radio stacks. Using the existing picture of faint rest-UV continua, weak high-ionization lines, and radio non-detections down to roughly 0.5-0.1 μJy at z∼5-6, the authors frame three main explanations: Compton-thick high-covering-factor BLR obscuration, intrinsically weak emission from very high accretion rates, or strong scattering inside a dense ionized cocoon. Their main result is that SKA-Low and SKA-Mid observations across 0.2-11 GHz and 1-1000 hour integrations should detect these sources in all three scenarios while separating them through their different radio SED shapes, depths, and possible variability. That makes the radio a decisive route to testing whether LRDs are genuinely AGN-powered, heavily buried, intrinsically X-ray weak, or governed by dense circumnuclear gas that suppresses their emission across other bands.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 1. Use this as the observational-motivation figure. It compiles the failed radio stacking attempts for photometrically selected LRDs and spectroscopically confirmed Type I JWST AGN, making the present upper-limit landscape immediately clear and showing why a step change in sensitivity is needed.
Figure 2. This is the key diagnostic figure of the paper. It compares the predicted radio SEDs for the three physical scenarios against SKAO detection limits across multiple bands and integration times, while also showing the host-galaxy star-formation contribution, so it directly encodes how SKAO can discriminate between obscuration, intrinsically weak accretion-powered emission, and electron-scattering suppression.
Figure 3. Include this as the concrete falsifiability figure. By plotting expected 1.4 GHz luminosities for GOODS-N JWST Type I AGN under the assumption that the full H emission is due to star formation, then comparing them with current VLA and future SKAO Band-2 limits, it shows how SKAO can test non-AGN interpretations for the bulk of the sample.

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2606.30711v1

Little Red Dots as Intermediate Mass, Super-Eddington Engines: Insights from Type IIn Supernovae and The 1837-1856 Great Eruption of $η$ Carinae

Rohan P. Naidu, Jorryt Matthee, Anna de Graaff, Alberto Torralba, Chris Ashall, Harley Katz, John Chisholm, Gabriel Brammer, Luc Dessart, Anna-Christina Eilers, Raphael E. Hviding, David O. Jones, Vasily Kokorev, Joel Leja, Hanpu Liu, Zhaoran Liu, Devesh Nandal, Pascal A. Oesch, Conor L. Ransome, Robert A. Simcoe, Wendy Q. Sun, Andrea Weibel, Mengyuan Xiao

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This paper argues that many hallmark Little Red Dot observables, including blackbody-like red continua, broad Balmer wings with P-Cygni absorption, and weak variability, are better matched by η Carinae’s Great Eruption and Type IIn supernovae than by a standard virial broad-line AGN picture. In the authors’ scenario, a dense slow wind from the central engine builds an optically thick pseudo-photosphere, while faster winds crash into that envelope and power the luminosity through shocks; electron scattering plus a clumpy partially ionized medium then shape the distinctive line profiles. Using an escape-velocity argument tied to the fastest outflowing absorbing gas, they infer typical engine masses below 10^5 M⊙ and more broadly favor intermediate-mass, strongly super-Eddington systems with M ≈ 10^3-10^6 M⊙ and Lbol/Ledd ≳ 5. The payoff is major: if LRD line widths are wind-formed rather than virial, the much-discussed “overmassive black holes” largely disappear, and LRDs instead become a plausible enshrouded growth phase on the path toward classical AGN and massive black-hole seeds.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 1 is the cleanest opening figure because it shows the paper’s core empirical motivation in one panel: LRDs, Type IIn supernovae, and η Carinae’s Great Eruption span orders of magnitude in luminosity but cluster at similar effective temperatures. That temperature convergence is exactly what the authors use to motivate recombination-regulated pseudo-photospheres in dense winds rather than ordinary unobscured AGN continua.
Figure 2 provides the central line-profile comparison underlying the whole analogy. By placing the Great Eruption, a Type IIn SN, and an LRD spectrum side by side, it shows that narrow Balmer cores, broad electron-scattering wings, and blueshifted absorption can all emerge naturally in enshrouded outflows, which is the paper’s main alternative to interpreting LRD broad lines as virial broad-line region gas.
Figure 8 is the best synthesis figure for the proposed physical picture and life cycle. It ties together the slow cold wind, the pseudo-photosphere, the fast wind, shock-powered radiation, and the partially ionized line-forming layers, making explicit how the same structure is meant to explain the continuum, Balmer absorption, broad wings, nebular emission, and eventual dust production.
Figure 9 is important because it operationalizes the paper’s mass argument instead of leaving it conceptual. The figure shows how the authors isolate the absorption component after removing the exponential wings and define a velocity proxy for the fastest cold-wind material, which is then used in the escape-velocity constraint on the central engine mass.
Figure 10 captures the paper’s bottom-line claim about black-hole demographics. It shows that once the line widths are treated as wind physics rather than virial motion, the typical LRD central engine moves into the intermediate-mass regime and sits much closer to the stellar-mass versus black-hole-mass relation, directly challenging the popular ‘overmassive black hole’ interpretation.

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2606.31515v1

The metallicities of little red dot host galaxies: LRDs are metal poor, but not pristine

G. P. Nikopoulos, D. Watson, C. L. Pollock, A. Sneppen, K. E. Heintz, J. Witstok, G. Brammer

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Using medium- and high-resolution JWST/NIRSpec spectra of 24 little red dots at z≈2.3-7, selected for compact red continua and broad Hα emission, the authors isolate the narrow-line components and measure host-gas abundances with the direct T_e method. They find a sample-average metallicity of Z_T_e≈0.08 Z_sun and T_e≈23,000 K, placing LRD hosts firmly in the metal-poor regime and roughly an order of magnitude below typical Seyfert or quasar hosts. A strong-line R-hat calibration reproduces the direct-T_e metallicities with only 4% scatter and highlights two especially extreme LRDs with metallicities below 1.3% solar. The key implication is that most LRDs are enriched enough to challenge pristine-gas collapse scenarios, yet remain so metal poor that low metallicity itself may be a defining trait of the class.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 2. Use this as the headline result figure. It directly compares the sample metallicity distributions from the direct T_e and R-hat methods, quantifies their agreement, marks the two extremely metal-poor outliers, and most importantly shows that most LRDs sit above the near-pristine metallicity limits invoked in direct-collapse scenarios.
Figure 3. This is the key diagnostic figure for why the paper trusts R-hat as a practical metallicity proxy. It shows which strong-line ratios track the direct-T_e abundances in LRDs and makes clear that the preferred calibration remains anchored to the narrow-line metallicities rather than the broad AGN-dominated components.
Figure 4. Include this for the observational cross-check. It tests whether direct-T_e metallicities derived from low-resolution PRISM data agree with grating-based measurements, which matters for judging how broadly the metallicity result can be extended across the existing LRD literature and archive samples.
Figure 5. This is the best population-synthesis figure in the paper. It shows that LRD host metallicities stay low across redshift, span only about 0.6 dex, and remain offset below comparison high-redshift galaxies and mass-metallicity expectations, supporting the claim that low metallicity is a stable class property rather than a one-off phase.
Figure 6. Use this as the host-galaxy context figure. By placing the well-constrained LRDs on the metallicity-SFR plane relative to the fundamental metallicity relation, it connects the abundance measurements to very low inferred stellar masses of order 10^8 M_sun and reinforces that these hosts are not ordinary massive AGN galaxies.

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2606.30715v1

Hunting Wandering 3<z<8 Black Holes: via Spatial Offsets in Ionization Ratio and Continuum Emission

Urvi Thakurdesai, Anthony J. Taylor, Steven L. Finkelstein, Gene C. K. Leung, Oscar A. Chavez Ortiz, Jonathan R. Trump, Bren E. Backhaus, Nikko J. Cleri, Francesco D'Eugenio, Fabio Pacucci, Anton M. Koekemoer, Pablo Arrabal Haro, Micaela Bagley, Mark Dickinson, Jeyhan Kartaltepe, Casey Papovich, Nor Pirzkal

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Using CEERS JWST/NIRSpec PRISM 2D spectroscopy, this paper searches 90 slit-centered galaxies at 3 < z < 8, including two known broad-line AGN, for localized high-ionization regions by comparing spatial [OIII]/Hβ profiles with the stellar continuum center. The authors identify 26 systems with significant localized [OIII]/Hβ peaks, and 12 of those show statistically significant offsets between the ionization peak and the continuum peak, with six reaching offsets larger than 1.5 pixels. They further test whether the offsets track line-ratio strength, finding no significant relation with the maximum [OIII]/Hβ value but a positive trend with the contrast between the off-center peak and the value at the continuum center. The main result is that spatially offset ionization in JWST slit spectra may be a practical way to flag wandering or off-nuclear black-hole growth in the early universe across samples much larger than targeted IFU programs.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 1. Use this figure to show how the visually inspected CEERS parent set is reduced to the final 90-galaxy sample through the intra-slit positional cut. That selection is central to the paper because the search for wandering black holes depends on trustworthy cross-dispersion spatial profiles that are not dominated by slit-edge losses or nodded-background contamination.
Figure 5. This is the clearest figure for the paper’s core measurement because it shows three concrete spatial-profile outcomes: a coincident ionization and continuum peak, a genuinely offset [OIII]/Hβ peak, and a uniform-ionization case. The combination of fitted spatial profiles, posterior peak locations, and NIRCam context images makes the offset definition intuitive and demonstrates exactly what kind of evidence promotes a source into the candidate off-nuclear category.
Figure 6. Include this figure because it distills an important non-result: the size of the spatial offset does not significantly correlate with the maximum [OIII]/Hβ value. That helps readers avoid equating stronger ionization ratios with stronger wandering-black-hole evidence and sharpens the interpretation of what the offset metric is actually capturing.
Figure 7. This figure carries one of the paper’s main quantitative synthesis results by showing that larger offsets are associated with larger spatial variation in [OIII]/Hβ across the central rows. It is especially worth highlighting because the caption explicitly notes the likely selection bias toward high-contrast systems, so the figure both supports and appropriately qualifies one of the strongest trends in the analysis.
Figure 8. This OHNO diagnostic plot is the best figure for connecting the spatial-offset measurement to physical interpretation. It shows where the offset sources fall in line-ratio space relative to the AGN versus star-formation boundary, while also preserving the paper’s key caveat that the calibration of this diagnostic at high redshift remains uncertain because of harder ionizing conditions.

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2606.29607v1

General Relativistic Shock Wave Solutions with Black Hole Formation: The Singular Isothermal Sphere Case

Chien-Ting J. Chen, Michael J. Cai, Fabio Pacucci

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This paper extends the general-relativistic singular isothermal sphere collapse problem to discontinuous flows, deriving self-similar shock solutions that connect a black-hole-forming interior to static, expanding, or collapsing outer envelopes. The main physical result is that the interior collapse fixes the black hole feeding rate, while shocks can move at up to about 0.4c and reduce the central accretion rate by roughly a factor of 5-7 relative to the smooth expansion-wave solution. Using a zero-velocity-surface coordinate match between Schwarzschild and comoving descriptions, the authors complete the global solution and show that the shock can release about 10% of the enclosed rest-mass energy, exceeding the canonical 5.7% Schwarzschild accretion efficiency. That gives an analytic energy budget for direct-collapse seed formation and a concrete framework for thinking about dense cocoons, early SMBH assembly, Little Red Dots, and other relativistic transients tied to nascent black holes.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 1 is the cleanest entry point for the new solution class because it shows how the collapse solutions with critical points connect a supersonically collapsing interior to a hydrostatic outer singular isothermal sphere through a shock, while also comparing directly to the older smooth expansion-wave solution. It makes the paper's core claim visually explicit: black-hole-forming SIS collapse in general relativity admits shocked, not just smooth, self-similar continuations.
Figure 2 is important because it broadens the result beyond a static envelope and demonstrates the full family of allowed shocked exteriors at fixed sound speed, including envelope collapse, breeze, and envelope expansion solutions. This is where the paper's statement about a rich shock solution space is most concrete, and the inset highlights how the shock links the shared collapsing interior to distinct outer flows.
Figure 3 best captures the coordinate-matching and interior-universality result by showing the comoving solutions anchored at the zero-velocity bridge, where the Schwarzschild and comoving descriptions coincide. It also makes clear that different hydrodynamic exteriors share the same comoving interior and differ mainly by the shock-shell location, which is central to the paper's global characterization of the growing black hole.
Figure 5 is the key quantitative summary for black-hole growth because it shows that the central accretion rate lies on a single curve set only by the interior parameter, independent of which shocked exterior is attached. This is the figure that most directly supports the headline conclusion that shocks suppress the black hole mass supply by about a factor of 7 relative to the smooth expansion-wave collapse.
Figure 6 is the strongest synthesis figure for the paper's astrophysical payoff because it ties sound speed to shock velocity, Mach number, and energy extraction efficiency in one place. It is the figure that most clearly supports the claims that shocks can reach relativistic speeds and that their energy release can approach about 10% of the enclosed rest-mass energy, exceeding the benchmark Schwarzschild radiative efficiency.

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2606.30253v1

No evolution in the number density of little red dots from cosmic dawn to cosmic noon

Federica Loiacono, Roberto Gilli, Marco Mignoli, Marcella Brusa, Francesco Calura, Marco Chiaberge, Andrea Comastri, Quirino D'Amato, Roberto Decarli, Ivan Delvecchio, Kazushi Iwasawa, Ignas Juodžbalis, Giorgio Lanzuisi, Roberto Maiolino, Stefano Marchesi, Giovanni Mazzolari, Colin Norman, Alessandro Peca, Isabella Prandoni, Matteo Sapori, Matilde Signorini, Paolo Tozzi, Eros Vanzella, Cristian Vignali, Fabio Vito, Gianni Zamorani, Anita Zanella

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Using JWST EIGER data in the J1030 field around SDSS J1030+0524, the authors sift 154 compact sources and identify five X-ray-undetected broad-line emitters with red NIRCam colors, then use them to build the little red dot bolometric luminosity function at z = 2.4 and z = 4.5. The key result is demographic: for LRDs with Lbol >= 3 x 10^44 erg s^-1, the number density shows no significant evolution from cosmic dawn to cosmic noon, with a cosmic-noon abundance of 3.4^{+5.6}_{-2.4} x 10^-5 Mpc^-3. At z = 2.4 this puts LRDs only about a factor of two below the full pre-JWST AGN population at similar luminosities, while the inferred black hole mass function shows the same qualitative behavior. That makes LRDs a major accreting black-hole population well past the earliest epochs, either implying efficient seed formation as late as cosmic noon or that LRDs trace a brief high-accretion phase in already mature black holes.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 3. Use this as the selection figure. It shows how the J1030 point-like sources separate in color-color and color-magnitude space, where the red compact sources lie relative to stars and X-ray AGNs, and which named broad-line X-ray-silent objects enter the final sample. This is the clearest visual definition of how the paper operationally identifies LRD candidates before the luminosity-function analysis.
Figure 4. Use this as the spectroscopic evidence figure. The line fits demonstrate the broad emission components that qualify the selected objects as broad-line AGN-like sources, including the z ~ 2.4 and z ~ 4.5 members that feed the demographic measurements. It is important because the paper's abundance claims rest on these compact red sources being genuine broad-line emitters rather than photometric interlopers.
Figure 5. Use this for the X-ray-silence diagnostic. By placing the sources as lower limits in X-ray bolometric correction versus bolometric luminosity, the figure shows how strongly they depart from the classical AGN expectation and quantifies the extreme X-ray weakness that is part of the LRD phenomenology. This matters because the sample is explicitly defined as X-ray-undetected broad-line sources and the comparison anchors them within the broader JWST-discovered X-ray-silent AGN population.
Figure 7. Use this as the main luminosity-function result. It compares the J1030-based LRD bolometric luminosity function at z = 2.4 and z = 4.5 with previous LRD estimates and with pre-JWST AGN and UV-selected AGN luminosity functions. This figure carries the paper's core quantitative claim that cosmic-noon LRDs remain abundant and that the z = 4.5 estimate is consistent with larger-area studies.
Figure 9. Use this as the bottom-line synthesis figure. It tracks the abundance of LRDs above the common bolometric-luminosity threshold as a function of redshift and directly shows the paper's headline conclusion of no significant decline from cosmic dawn to cosmic noon. The comparison to classical AGNs, X-ray-selected AGNs, and model predictions makes this the most important single figure for the paper's evolutionary claim.

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2607.00084v1

Little Red Dots at z~2 in EIGER reveal a gentle decline with respect to their peak number density at z~5

Shrriya Kapoor, Jorryt Matthee, Alberto Torralba, Ivan G. Kramarenko, Rongmon Bordoloi, Jenny E. Greene, Edoardo Iani, Daichi Kashino, Zhaoran Liu, Ruari Mackenzie, Sara Mascia, Rohan P. Naidu, Rob Simcoe

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Using 140 arcmin^2 of deep EIGER JWST/NIRCam imaging plus F356W slitless spectroscopy, this paper applies an improved blind broad-line search to find 19 broad-line sources at z=1.55-3.18 from rest-frame near-infrared lines, and classifies 5 as little red dots (LRDs) and 14 as classical AGNs. The main discriminator is a combined spectro-photometric picture in which LRDs dominate only at faint optical luminosities around M5100≈-20, span a range of Balmer-break strengths, and are cleanly separated from classical AGNs by the He I/Paγ ratio, which also appears to anti-correlate with Balmer-break strength; the two reddest LRDs additionally show blueshifted He I absorption. The z~2 LRDs occupy a similar optical-luminosity range to higher-redshift LRDs, consistent with ~10^6 M⊙ black holes radiating near Eddington. Their inferred number density of about 7×10^-6 cMpc^-3 at z=1.9-2.5 shows that LRDs are at most a few percent of the AGN population by this epoch and that the drop from the z~5 peak is real but gentler than some earlier claims suggested.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 2. Use this as the core discovery figure: it shows the actual 2D NIRCam WFSS detections for the five LRDs, including the continuum-subtracted emission-line maps used by the blind search. It makes the sample definition concrete and lets readers see how the broad-line signatures are identified in practice.
Figure 5. This figure is the cleanest overview of how the authors separate LRDs from the rest of the broad-line sample in observed parameter space. The optical-luminosity versus size plane, together with flags for X-ray detections, He I outflows, template fits, and high He I/Pa ratios, directly supports the claim that classical AGNs dominate at higher luminosity while LRDs take over at the faint end.
Figure 6. Recommend this for the paper’s strongest object-level spectroscopic evidence. The fitted He I+Pa profiles show that two of the reddest LRDs have blueshifted He I absorption, a result highlighted in the abstract and important for the dense-gas, self-absorption interpretation.
Figure 7. This is the most important physical-diagnostic figure because it shows that the integrated He I 1.083 μm to Paγ ratio cleanly separates LRDs from non-LRD broad-line sources and appears to anti-correlate with Balmer-break strength. It ties the line physics directly to the SED differences that motivate the LRD classification.
Figure 11. Choose this as the bottom-line synthesis figure. It places the new z~2 measurement into the redshift evolution of LRD number density and visually communicates the paper’s main conclusion that the decline from the z~5 peak is confirmed but is more gradual than previously emphasized.

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2606.31312v1

Dissecting the Obscured Core of GN20: an Active Galactic Nucleus Outshone by Young Stars

M. Hamed, L. Colina, P. G. Pérez-González, J. Álvarez Márquez, A. Crespo Gómez, L. A. Boogaard, A. Bik, H. Übler, S. E. I. Bosman, A. Alonso-Herrero, M. Perna, S. Arribas, L. Ulivi, M. Annunziatella, L. Costantin, A. Labiano, C. -L. Liao, C. Prieto-Jiménez, P. van der Werf, F. Walter

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This paper uses spatially resolved CIGALE SED fitting to separate the ∼1 kpc nuclear core of GN20 from the full 9.9 kpc galaxy, combining JWST NIRCam, MIRI, NIRSpec PRISM pseudo-continuum, HST, and millimeter data. The central result is that the galaxy-wide SED is overwhelmingly star-formation powered, with only a marginal integrated AGN fraction of 0.09 ± 0.02, while the nucleus requires a much stronger AGN contribution of 0.34 ± 0.05 to explain a rest-frame 2.5–3.6 μm mid-infrared excess from torus-heated dust. That means the AGN contributes about one-third of the nuclear infrared luminosity but only about 9% of the total L_IR, naturally explaining why integrated diagnostics and earlier Spitzer limits made the source look starburst-dominated. The broader significance is that GN20 looks like a buried-black-hole case where only JWST-resolution, nuclear-scale decomposition can uncover ongoing early SMBH growth inside an extreme z = 4.055 dusty starburst.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 1. Use this to show the measurement geometry that drives the paper’s main result: the compact nuclear aperture at r = 0.14 arcsec versus the much larger integrated aperture at r = 1.4 arcsec. The wavelength-dependent channel maps also make clear that the authors are isolating a distinct core within a much more extended system, which is essential context for why integrated photometry misses the AGN.
Figure 2. This figure is a clean observational demonstration that the core and integrated SED shapes differ before any modeling is imposed. It highlights the core non-detections at shorter wavelengths and the relative rise toward the mid-infrared, which motivates the claim that a buried nuclear component is emerging only at longer rest-frame wavelengths.
Figure 3. This is the paper’s key evidence figure because it directly compares the best-fit decomposed SEDs for the nucleus and the whole galaxy and shows that the core needs an AGN component while the integrated aperture does not. The no-AGN residuals in the core, especially around the F1280W and F1800W excess, are the most compact visualization of the conclusion that torus-heated dust is required in the center of GN20.
Figure 4. Include this later comparison figure because it places GN20’s core mid-infrared excess in the context of other extreme high-redshift dusty or AGN-hosting systems. It matters for the digest because it connects the GN20 nuclear SED to a broader population of obscured, rapidly growing black holes whose AGN signatures would be diluted or missed in unresolved galaxy-scale measurements.

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2606.28296v1

Memoirs of the curvaton: non-perturbative non-Gaussianity and supermassive primordial black holes

S. Allegrini, A. J. Iovino, G. Perna, H. Veermäe

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This paper derives the full local non-Gaussian map ζ = F(ζ_G) for curvaton models beyond the standard quadratic case, using an abbreviated-action treatment that tracks field-dependent oscillation onset and changes to the effective equation of state in the adiabatic regime. Across quadratic, monomial, quartic, and cosine potentials, the authors show that self-interactions can either enhance or suppress the resulting non-Gaussianity, and that in the strongly non-Gaussian regime the full non-perturbative mapping can substantially suppress the curvature power spectrum relative to naive perturbative expectations. The main application is a bottom-up primordial route to supermassive black-hole seeds: strongly positive curvaton non-Gaussianity can produce PBH seeds with peak amplitudes A_pk ~ 10^-5 while remaining compatible with COBE/FIRAS μ-distortion bounds. That makes axion-like cosine curvatons an especially natural version of a primordial seeding channel for JWST Little Red Dots.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 5. This is the key self-interaction figure for the quartic case: it compares numerical and analytical determinations of F(ζ_G) and then scans how the mapping changes as the self-interaction strength s moves from the quadratic toward the quartic limit. Use it to show concretely that self-interactions do not just perturb the quadratic result, but can qualitatively reshape the non-Gaussian map that drives the paper’s later phenomenology.
Figure 6. This is the most important potential-specific figure for the paper’s preferred axion-like scenario. The left panel shows how the cosine potential changes N_dec(σ)-N_0, while the right panel displays the resulting F(ζ_G) for several benchmark choices of f and background field, making clear why the cosine curvaton can naturally generate the strong positive non-Gaussianity highlighted in the abstract.
Figure 9. This figure connects the derived non-Gaussian map directly to the curvature power spectrum. The left panel shows how F(ζ_G) changes with r_dec, and the right panel demonstrates the resulting full non-Gaussian power spectra, which is central to the paper’s claim that strong non-Gaussianity can suppress power in a way missed by truncated treatments.
Figure 11. This is the conclusion-driving phenomenology figure. It combines the full non-Gaussian power spectra with μ-distortion constraints and PBH abundance, and directly shows the parameter dependence behind the headline result that supermassive-PBH seeds can be produced at peak amplitudes compatible with COBE/FIRAS bounds.

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2606.28311v1

Kinematic detection of dusty outflows from active galactic nuclei: Polycyclic aromatic hydrocarbon kinematics of type 2 quasars with JWST/MIRI spectroscopy

Fergus R. Donnan, Cristina Ramos Almeida, Omaira González Martín, Karin Sandstrom, Anelise Audibert, Marina Bianchin, Miguel Pereira-Santaella, Ismael García-Bernete

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This paper uses JWST/MIRI MRS observations of five z~0.1 QSOFEED type 2 quasars and PCA tomography of PAH features to directly probe dust kinematics. The main result is that the 11.3 μm PAH feature yields velocity maps in three systems, and all three show PAH outflows, most clearly after subtracting rotating-disk kinematics, with H2 rotational lines leaving consistent residual outflow signatures. By comparison with lower-Eddington-ratio Seyferts, the authors argue that dusty outflows are likely more common when λ_Edd ≳ 0.1, in line with these luminous QSO2s occupying blowout or polar-wind territory. They do not recover usable 6.2 μm PAH velocity maps, which is consistent with ionised or smaller PAHs being profile-variable or suppressed in AGN, so the strongest kinematic evidence here comes from the more neutral 11.3 μm carriers.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 2. This PCA decomposition for J1509 is the clearest methods figure because it shows exactly which eigenspectrum carries the PAH velocity information and which component is dominated by PSF-subtraction artifacts. It helps the reader see why PCA tomography is necessary for broad PAH bands whose intrinsic profiles make conventional spaxel-by-spaxel fitting difficult.
Figure 3. These sample-wide velocity maps are the core overview figure because they place the PAH, ionised-gas, and molecular-gas kinematics side by side for all five quasars on a common velocity scale. This is where the reader can immediately see that 11.3 μm PAH kinematics are only recovered in three objects and compare those patterns to the host-galaxy disk major axes.
Figure 6. The disk-subtracted velocity maps for J1509 provide one of the cleanest demonstrations that the PAH signal is tracing an outflow rather than simple disk rotation. The added CO(2-1) contours and the separate PAH and H2 outflow position angles make this a strong multi-phase evidence figure for the paper’s central claim.
Figure 9. This comparison of column density versus Eddington ratio is the main synthesis figure linking the new QSO2 detections to the earlier Seyfert sample. It matters because it visually supports the paper’s broader interpretation that dusty PAH outflows become more common in the blowout or IR polar-outflow regime at higher λ_Edd.
Figure 10. These velocity profiles along the outflow axis for J1509, J1430, and J1100 are the most direct kinematic comparison between the 11.3 μm PAH feature and the H2 lines after disk subtraction. They show how the dusty and molecular components track each other spatially and kinematically across the three detections, strengthening the case for a genuine outflowing dusty phase.

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2606.27427v1

SEEDZ: Rapid Galaxy Assembly as a Pathway to Supermassive Stars, Dense Stellar Environments and Massive Black Hole Seeds

Lewis R. Prole, John A. Regan, Daxal Mehta, Devesh Nandal, Rüdiger Pakmor, Ricarda S. Beckmann, Michael Tremmel, Martin G. Haehnelt, Simon C. O. Glover, Ralf S. Klessen, John H. Wise, Sophie Koudmani, Martin A. Bourne, Debora Sijacki, John Brennan, Pelle van de Bor, Paul C. Clark

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Using the SEEDZ hydrodynamic simulations, this paper argues that the key pathway to heavy black-hole seed formation is not pristine isolation but unusually rapid galaxy assembly: halos with virial-scale growth rates of at least about 1 M_sun/yr are the ones that drive the >1 M_sun/yr inflows into 10 pc required by the model, while also sustaining ~0.1 M_sun/yr into the inner 1 pc and keeping the central 10-100 pc dense. In these systems, heavy seeds generally appear about 100 Myr after the first stars and stellar-mass black holes, linking seed formation to continued post-collapse growth rather than the very first episode of star formation. By z=10, most seeds in the simulation form in near-solar-metallicity environments, with only a minority in low-metallicity gas, so the paper shifts the emphasis from classic metal-free channels toward rapidly assembled, already enriched galaxies. Under the paper's explicit assumption that only low-metallicity seeds with sustained >0.02 M_sun/yr accretion for 2 Myr become supermassive stars, the inferred SMS number density is 0.1 cMpc^-3, high enough that only 10^-4 would need to be observable to explain the Little Red Dot population.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 1. Use this as the setup figure because it makes the paper's main claim visually obvious: heavy-seed-forming halos have systematically faster assembly histories, higher growth rates, and more merger-driven mass build-up than halos that never cross the inflow threshold. It directly connects large-scale halo growth to the small-scale heavy-seed criterion that drives the rest of the paper.
Figure 3. This is the core physical-diagnostic figure showing that heavy-seed-forming halos differ structurally, not just historically. The radial profiles demonstrate the enhanced inflow, higher central densities, and larger enclosed gas masses that distinguish seed-forming systems within the central 10-100 pc and support the claim that virial-scale accretion feeds dense inner regions.
Figure 5. Include this figure to document whether newly formed seeds remain in the high-accretion regime relevant for a supermassive-star progenitor. The accretion histories over the first 2 Myr and the rate distribution at 2 Myr are the paper's direct bridge between the heavy-seed prescription and the sustained >0.02 M_sun/yr condition invoked for SMS survival and growth.
Figure 6. This is the most efficient figure for the metallicity-dependent interpretation. It shows how formation metallicity correlates with early growth, surrounding gas supply, and formation redshift, while explicitly marking the metallicity-accretion region the authors identify as compatible with SMS formation, which is central to their LRD relevance argument.
Figure 8. Use this as the synthesis figure because it converts the simulation results into population-level implications. By separating all heavy seeds, metal-enriched cluster-like channels, and the low-metallicity plus sustained-inflow SMS subset, it delivers the bottom-line number-density comparison that motivates the connection to observed Little Red Dots.

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2607.00093v1

Search for Quasar Pairs with ${\it Gaia}$ Astrometric Data. III. Discovery of 9 dual and projected quasars

Qihang Chen, Zizhao He, Zhuojun Deng, Liang Jing, Xingyu Zhu, Jianghua Wu

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This paper spectroscopically follows up 11 Gaia-selected quasar-pair candidates from the MGQPC catalog and confirms 9 real quasar pairs: 6 dual quasars and 3 projected quasars. The long-slit spectra identify one dual system at z ~ 3.1 and separate physical pairs from contaminants, including a wide-separation projected quasar with a lens-like configuration and quasar-star look-alikes. A practical result is that some companions were previously missed because of blending, slit geometry, faintness, or survey limitations, while companion photometric redshifts help suppress projected-quasar contamination before follow-up. The main caveat is that a lensed-quasar interpretation cannot yet be fully excluded for three of the nominal dual quasars, making the paper as much about confirmation strategy as about sample growth.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 2. This is the paper's core discovery figure. The spectra directly establish the six dual quasars through quasar emission-line identifications in both members, and the public-spectrum overlays also make clear why several companions were previously missed because of blending, faintness, or incomplete earlier spectroscopy.
Figure 3. Include this to show that the follow-up program does not only add dual quasars but also cleanly identifies projected quasars. It is the direct evidence for the three redshift-mismatched quasar projections, including the lens-like wide-separation case emphasized in the paper's discussion.
Figure 4. This is the most important caveat and interpretation diagnostic. The B/A spectral flux-ratio curves show emission-line-dependent differences that argue against a simple lensing explanation in several systems, while also illustrating why the lensed-quasar hypothesis cannot be fully excluded for three of the nominal duals.
Figure 5. This later diagnostic captures one of the paper's main practical lessons for future searches. By placing member B in quasar color space, it shows how color information and the companion photometric-redshift estimates from Paper II can reduce contamination from projected quasars before expensive spectroscopic confirmation.
Figure 6. This figure is worth including because the abstract explicitly highlights quasar-star projections that mimic lensed quasars. The stellar absorption features, including H and the Ca II triplet in the contaminant objects, demonstrate a concrete failure mode for quasar-pair and lens searches and motivate the paper's confirmation-strategy discussion.

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2606.31673v1

AGN Feedback: The impact of galactic-scale radio jets on the interstellar medium in starbursting obscured AGN

M. Polletta, C. J. Lonsdale, P. Pallavi, G. Vietri, A. E. Kimball, P. Franzetti, C. J. Lonsdale

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Polletta et al. present an ELT/SHARP science case aimed at catching AGN feedback in the act in z~2 radio dusty obscured galaxies: heavily obscured, luminous AGN with recent starbursts and resolved radio jets on roughly 1-15 kpc scales. The paper argues that these sources trace a short-lived phase, shorter than 10^5 yr, in which a newly triggered jet and a deeply buried quasar coexist, making them unusually clean laboratories for testing whether feedback is suppressing star formation while clearing the nucleus. SHARP/VESPER integral-field spectroscopy would deliver resolved maps of stellar ages, star-formation-rate surface density, gas density, ionization state, and stellar and ionized-gas kinematics, to be compared directly with the radio structures. The proposed sample contains 11 such AGN at 1.5 < z < 2.5, and the multi-IFS strategy would scale this to at least 110 galaxies in 55 hours, turning the program into a direct test of jet-driven and radiative feedback at cosmic noon.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 2. Use this as the motivating complexity figure. It shows the JWST/NIRSpec [O III] morphology and velocity-sliced structure of the obscured AGN J1652, together with the VESPER field of view, making clear why spatially resolved spectroscopy is needed to disentangle outflowing gas, shocked regions, companions, and tidal features in feedback-dominated systems.
Figure 3. This is the cleanest sample-definition figure because it shows four of the selected radio DOGs in VLA 10 GHz imaging with annotated redshifts and radio morphologies. It establishes that the targets really do host resolved, galactic-scale radio structures rather than unresolved radio cores, which is central to the paper's jet-ISM feedback case.
Figure 5. This figure provides the most direct physical diagnostic in the paper excerpt. The X-Shooter spectrum of J1500-06 shows two Gaussian components, including a component blueshifted by about -360 km/s, and the line-ratio behavior flagged in the caption as evidence for shocks, tying compact radio activity to disturbed ionized gas and outflow signatures.
Figure 6. Include this later synthesis figure because it connects radio power, source size, and SHARP/VESPER observing feasibility across the full sample. It shows how the selected radio components occupy the sub-galactic to galactic scale regime and why a single IFS often suffices for one component while multiple IFSs are needed for more complex jet structures, directly supporting the proposed experimental design.

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2606.28559v1

DESI DR2 Reference Mocks: Clustering results from UCHUU ELGs and QSOs

R. Vaisakh, J. Lasker, R. Kehoe, A. Amalbert, N. Khan, E. Fernandez-Garcia, F. Prada, M. S. Wang, J. DeRose, S. Bailey, A. J. Ross, J. Aguilar, S. Ahlen, D. Bianchi, D. Brooks, F. J. Castander, T. Claybaugh, K. S. Dawson, A. de la Macorra, S. Ferraro, J. E. Forero-Romero, E. Gaztanaga, Satya Gontcho A Gontcho, G. Gutierrez, C. Hahn, M. Ishak, R. Joyce, S. Juneau, T. Kisner, A. Kremin, C. Lamman, M. Landriau, M. E. Levi, M. Manera, R. Miquel, A. D. Myers, S. Nadathur, W. J. Percival, I. Perez-Rafols, G. Rossi, E. Sanchez, D. Schlegel, H. Seo, G. Tarle, B. A. Weaver, R. Zhou, H. Zou

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This paper builds DESI DR2 reference mocks for emission-line galaxies and quasars by populating the Uchuu N-body simulation with a modified SHAM model, fitting ELGs over 0.8 < z < 1.6 and QSOs over 0.8 < z < 2.1. The key empirical tweak is tracer-specific: QSO clustering is reproduced with a redshift-dependent satellite fraction and a fixed characteristic velocity scale, while ELGs require selecting satellites with low velocities relative to their centrals and an increasing V_mean with redshift. With those choices, the mocks recover the observed redshift evolution of number density, the monopole across the fitted 3 to 70 h^-1 Mpc range, and also give reasonable quadrupole, projected-correlation, and power-spectrum behavior without being directly fit to all of them. The payoff is a high-fidelity lightcone set for DESI clustering analyses that also yields large-scale bias trends and halo-occupation constraints, sharpening how ELGs and QSOs map onto dark matter halos.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 1. Use this figure to show that the mocks are not just tuned to clustering amplitude but also track the observed comoving number-density evolution of both ELGs and QSOs across 0.8 < z < 2.1. That redshift-dependent abundance match is foundational for any later claim that the lightcones are realistic survey references rather than single-epoch fits.
Figure 3. This is the clearest summary of the paper’s modified SHAM ingredients. It isolates the main physical and phenomenological result of the modeling: QSOs prefer an increasing satellite fraction with redshift at fixed V_mean, while ELGs are better described by a fixed satellite fraction and a redshift-rising V_mean, including the low-relative-velocity satellite selection that distinguishes the ELG treatment.
Figure 4. Choose this as the main evidence figure because the abstract’s central claim is that the mocks reproduce DESI DR2 clustering over the fitted range. The monopole comparison directly demonstrates agreement between data and the best-fit modified SHAM models for both tracers, making it the most important validation panel in the paper.
Figure 14. This figure connects the successful clustering fit back to the galaxy-halo connection, which the abstract explicitly frames as a key outcome. The separate central and satellite occupation curves for ELGs and QSOs make clear how the two tracers inhabit halos differently and why the modified SHAM prescriptions are physically informative rather than purely empirical.
Figure 15. Use this as the synthesis figure for the paper’s large-scale conclusions. It shows the redshift evolution of bias measured in both DESI data and Uchuu mocks, confirming that the calibrated lightcones capture the monotonic rise in tracer bias and therefore provide a useful basis for future DESI cosmological analyses.

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2606.27675v1

OzSSy1: The Australian Southern Seyfert-1 Spectroscopic Atlas and Catalogue at z < 0.1

Neelesh Amrutha, Christian Wolf, Christopher A. Onken, Wei Jeat Hon, Samuel Lai, Rachel Webster

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OzSSy1 delivers a publicly available spectroscopic atlas and catalogue of 887 southern broad-line AGN at z < 0.1, observed with the WiFeS integral-field spectrograph at R~3000 and extracted in a 6.7 arcsec aperture. The sample is built to be a largely complete nearby Seyfert-1 census, drawn mainly from the 6dFGS broad-line AGN population and supplemented with S7 Seyferts and bright point-source AGN missed by galaxy-based selection. Each object comes with AGN-host continuum decomposition and emission-line fits for the Balmer, helium, and standard narrow forbidden lines, making the release immediately useful for single-epoch line measurements, demographic work, and classification. Its main value is as a modern homogeneous southern reference set for long-baseline variability studies and future time-domain surveys, especially where older 6dFGS spectra were not ideal as flux-calibrated comparison epochs.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 2. Use this as the sample-definition figure. It shows how the atlas populates magnitude, redshift, and AGN continuum-luminosity space, and it makes clear that the catalogue combines host-selected 6dFGS Seyferts with supplementary bright AGN to improve completeness at the luminous, point-source end.
Figure 6. This is the clearest figure for what the data product actually contains. The decomposition examples demonstrate the separation of AGN continuum and host galaxy light, the fitted emission-line model, and the range of host contrast and Balmer-line quality that users should expect across the atlas.
Figure 10. Include this to document how the catalogue’s type labels are assigned. The decision tree is central for any reader who wants to use the release for population work, because it turns the fitted spectral components and quality cuts into the final AGN classifications and identifies the spectra excluded as bad quality.
Figure 9. This is a strong physics-diagnostic figure rather than a setup figure. The Balmer-line FWHM comparisons test the internal consistency of the broad-line fits across Hα, Hβ, and Hγ, showing that Hβ/Hα follows the reverberation-mapping-based expectation while Hγ/Hβ departs from it.
Figure 15. This figure best captures why the atlas matters beyond cataloguing. The MCG 06 30 015 flare sequence shows how a homogeneous baseline spectrum plus repeat WiFeS observations can isolate transient spectral changes on week-scale follow-up, exactly the kind of use case the release is designed to enable for time-domain AGN science.