Weekly issue

Week 2, 2026

Jan 5–11, 2026

Week 2, 2026 includes 5 curated papers, centered on LRD, QSO, overmassive BH.

2601.06015v1

VENUS: Two Faint Little Red Dots Separated by $\sim70\,\mathrm{pc}$ Hidden in a Single Lensed Galaxy at $z\sim7$

Hiroto Yanagisawa, Masami Ouchi, Miriam Golubchik, Masamune Oguri, Seiji Fujimoto, Vasily Kokorev, Gabriel Brammer, Fengwu Sun, Minami Nakane, Yuichi Harikane, Hiroya Umeda, Hollis B. Akins, Hakim Atek, Franz E. Bauer, Maruša Bradač, John Chisholm, Dan Coe, Jose M. Diego, Henry C. Ferguson, Steven L. Finkelstein, Lukas J. Furtak, Kohei Inayoshi, Anton M. Koekemoer, Jorryt Matthee, Rohan P. Naidu, Yoshiaki Ono, Richard Pan, Johan Richard, Luke Robbins, Chris Willott, Adi Zitrin, Ricardo O. Amorín, Larry D. Bradley, Volker Bromm, Christopher J. Conselice, Pratika Dayal, Jeyhan S. Kartaltepe, Paulo A. A. Lopes, Ray A. Lucas, Georgios E. Magdis, Nicholas S. Martis, Casey Papovich, Daniel Schaerer, Francesco Valentino, Eros Vanzella, Joseph F. V. Allingham, Norman A. Grogin, Mauro González-Otero, Massimo Ricotti, Rogier A. Windhorst

Theme match 4/5

Digest

JWST VENUS imaging of PLCK G004.5−10.5 uncovers Red Eyes, a spatially resolved pair of little red dots embedded in a single z∼7 lensed galaxy; the lens geometry and a NW counter-image require two distinct sources. The components are separated by ∼70 pc in the source plane and magnified by μ∼20, lying ~1 Re off the host center; the host is a typical SFG with M_UV,int≈−19 while each LRD is UV-faint (M_UV,int≳−16). SED fits to the multiple images demand an added LRD (blackbody-like) component, whereas dusty SFG-only models underpredict the UV. Because these LRDs would be invisible without lensing, the work suggests hidden, off-center LRDs may be common in typical z∼7 galaxies, consistent with IMBH (10^4–10^6 M⊙) seeds forming in disk star clusters and later merging toward SMBH growth.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 1: Inspect the lens map and image-plane geometry—note Red Eyes’ positions relative to the critical curves and the NW counter-image, which argues for two discrete LRDs and sets up the source-plane reconstruction yielding the ~70 pc separation.
Figure 2: Check how LRD-SW1, LRD-SW2, and LRD-NW pass the color/slope thresholds while nearby SFG components fail; the cyan intrinsic points show that, unlensed, the system would not be flagged as an LRD.
Figure 3: In the SW cutouts and SEDs, compare fits with and without the added blackbody component; dusty SFG-only models underpredict the UV, and the redshift posterior confirms the z∼7 solution for the LRD components.
Figure 4: Repeat the SED scrutiny for the NW image to see consistency across counter-images, supporting the magnification (μ∼20) and the LRD interpretation for both components.

Tags

2601.04955v1

Rapid emergence of overmassive black holes in the early Universe

Sunmyon Chon, Shingo Hirano, Tomoaki Ishiyama, Seok-Jun Chang, Volker Springel

Theme match 5/5

Digest

Cosmological radiation–hydrodynamic simulations (AREPO) track SMBH birth and early growth in overdense proto-cluster regions illuminated by strong FUV fields. The runs naturally form ~10^6 Msun heavy seeds from supermassive-star collapse that quickly assemble dense, optically thick disks whose electron scattering yields broad Halpha and Balmer absorption akin to little red dots. Brief (<Myr), super-Eddington episodes propel growth to ~3×10^7 Msun by z~8, keeping BH-to-stellar mass ratios above local relations and overlapping the observed LRD locus. Light (Pop III–remnant) seeds in the same environment fail to grow comparably, linking LRDs to a short-lived, enshrouded heavy-seed phase that precedes overmassive quasars.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 1: Use panels (e)–(f) to read off the heavy-seed (MBH1/MBH2) mass build-up and the duration/peak of the super-Eddington bursts, and contrast with the stalled Pop III light-seed track; maps (a–d) show the FUV-illuminated environment and subsequent migration/merger into the neighbor halo.
Figure 2: Inspect the simulated M_BH–M_star track versus LRD and quasar points to see BH-to-stellar mass ratios exceeding the local relation, and note when the BH enters the host’s virial radius along the path that matches LRDs.
Figure 3: Check how the progenitor cloud fragments into a compact multiple system, with bursty accretion and mergers keeping stars in an inflated supergiant phase that mutes UV feedback—setting up collapse to ~10^6 Msun heavy seeds.
Figure 4: Follow the circum-BH disk from thick to thin; the radial density and emissivity profiles demonstrate the conditions for Balmer absorption and electron-scattering–broadened Halpha, connecting the simulated disk directly to LRD spectra.

Tags

2601.06255v1

GA-NIFS: high prevalence of dusty and metal-enriched outflows in massive and luminous star-forming galaxies at $z\sim3-9$

B. Rodríguez Del Pino, S. Arribas, M. Perna, I. Lamperti, A. Bunker, S. Carniani, S. Charlot, F. D'Eugenio, R. Maiolino, H. Übler, E. Bertola, T. Böker, G. Cresci, G. C. Jones, C. Marconcini, E. Parlanti, J. Scholtz, G. Venturi, S. Zamora

Theme match 3/5

Digest

JWST/NIRSpec IFU data from GA-NIFS targets 15 massive, luminous star-forming systems at z≈3–9 (split into 40 galaxies/regions) with no AGN and searches for ionized outflows via [O III]5007 and Hα line profiles. Broad components signal outflows in 14 galaxies/regions with σout=130–340 km s−1 and vout=170–600 km s−1; the outflowing gas is dustier (ΔAV≈0.59 mag) and more metal-enriched (+0.13 dex) than the host ISM. Typical vout fall below escape speeds and mass-loading factors are low (η≤1 in 9/14), implying weak suppression of star formation. Combined with lower-mass samples, vout correlates with SFR, pointing to early massive SFG outflows that primarily redistribute dust and metals locally rather than evacuate them to the CGM.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Line-profile decompositions of [O III]5007 and Hα showing narrow+broad components for representative regions—use these to verify the detection fraction (14/40) and read off σout and vout ranges.
Maps comparing AV and metallicity for the broad (outflow) versus systemic components—inspect spatial offsets and quantify the ΔAV≈0.59 mag and +0.13 dex enrichment of the outflowing gas.
vout versus SFR relation combining GA-NIFS with literature lower-mass samples—check slope, scatter, and how these high-mass, luminous systems extend the trend.
vout (or vout/vesc) compared to host escape velocities—assess what fraction cannot escape and how gravitational potential shapes retention.
Mass-loading factor (η) versus M⋆ or SFR—confirm that most η values lie ≤1 and evaluate the implication for feedback-driven quenching.

Tags

2601.02865v1

GATOS XI : Excess dust heating in the Narrow Line Regions of nearby AGN revealed with JWST/MIRI

Houda Haidar, David J. Rosario, Ismael García-Bernete, Almudena Alonso-Herrero, Anelise Audibert, Steph Campbell, Chris M. Harrison, Tiago Costa, Laura Hermosa Muñoz, Françoise Combes, Dimitra Rigopoulou, Claudio Ricci, Cristina Ramos Almeida, Enrica Bellocchi, Peter Boorman, Andrew Bunker, Richard Davies, Daniel Delaney, Tanio Díaz Santos, Federico Esposito, Victoria A. Fawcett, Poshak Gandhi, Santiago García-Burillo, Omaira González-Martín, Erin K. S. Hicks, Sebastian F. Hönig, Alvaro Labiano, Nancy A. Levenson, Enrique Lopez-Rodriguez, Chris Packham, Miguel Pereira-Santaella, Rogemar A. Riffel, Alberto Rodríguez Ardila, John Schneider, T. Taro Shimizu, Marko Stalevski, Montserrat Villar Martín, Martin Ward, Lulu Zhang, Gillian Leeds, Fergus R. Donnan

Theme match 3/5

Digest

JWST/MIRI imaging of eight nearby GATOS AGN isolates extended NLR dust and tests its heating budget. Four nuclei—ESO 428‑G14, NGC 4388, NGC 3081, and NGC 5728—show 100–200 pc dust structures whose morphology tracks the radio ejecta and coronal [Si VI]. Spatially resolved SEDs reveal steeper MIR slopes than in star‑forming clumps and blackbody fits yield 150–220 K at ~150 pc from the nucleus. Simple AGN-illumination models underpredict the flux, while shocks with v_shock ≈ 200–400 km/s in dense gas can close the gap, elevating shocks as a key driver of extended MIR dust emission in AGN centers.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Fig. 1: PSF‑subtracted, line‑decontaminated F1000W maps for ESO 428‑G14, NGC 4388, NGC 3081, NGC 5728—inspect 100–200 pc dust features aligned with [Si VI] and radio contours; note arrows marking [Fe II]‑enhanced shock zones.
Fig. 2: Companion F1000W panels for NGC 7172, NGC 2992, NGC 3227, NGC 5135—compare weaker/absent extended dust to the four detections to gauge how NLR geometry or activity level modulates dust visibility.
Fig. 3: Five‑band MIRI SEDs (normalized by F1500W)—verify that NLR ROIs have systematically steeper MIR slopes than star‑forming clumps across galaxies, establishing a distinct heating mechanism.
Fig. 4: Monte‑Carlo blackbody fits at 150 pc in shock‑dominated apertures—read off 150–220 K temperatures and confidence ranges, the key inputs showing why AGN illumination alone is insufficient.

Tags

2601.03338v1

Fast rotations in galaxies at cosmic noon indicate central concentration of stars, dark matter or massive black holes

Fernanda Roman-Oliveira, Francesca Rizzo, Filippo Fraternali

Theme match 2/5

Digest

Three ALPAKA discs at z=0.56, 1.45, and 2.10 are modeled by combining ALMA CO/[CI] kinematics (CO(2-1), CO(5-4), [CI] 3P2–3P1) with JWST/NIRCam rest‑NIR imaging (F277W/F444W) to decompose their rotation curves. The models fit the outer discs but systematically underpredict inner speeds, revealing a central mass excess beyond stars+cold gas. The authors attribute this to underestimated bulge masses from M/L variations or dust, or to overmassive black holes; alternatively, dark‑matter halos may be more centrally concentrated than standard profiles. This is among the first robust baryon‑anchored decompositions at z>0.5, pointing to early central mass build‑up at cosmic noon.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Rotation‑curve mass decompositions for the three ALPAKA galaxies: inspect the inner few kpc where model curves fall below the data to gauge the size of the velocity excess per galaxy.
JWST/NIRCam morphology (F277W for the z=0.56 disc; F444W for the z=1.45 and z=2.10 discs): check spiral structure, central light concentration, and dust lanes that could bias bulge M/L.
ALMA moment‑0 maps and velocity fields with beam ellipses: verify disc regularity, radial extent, and the number of independent resolution elements along the major axis (≈3.8/4.2/4.2) feeding the kinematic fits (3D BAROLO).
Halo‑model comparison panels (e.g., NFW vs enhanced‑concentration variants): assess how inner density slope/concentration shifts reduce residuals in the central rotation.
Tests adding a central point mass or radial M/L gradients: see how much BH mass or M/L increase is required to match the observed inner velocities.