Weekly issue

Week 37, 2025

Sep 8–14, 2025

Week 37, 2025 includes 6 curated papers, centered on LRD, high-z, QSO.

2509.09607v1

Discovery of Multiply Ionized Iron Emission Powered by an Active Galactic Nucleus in a z~7 Little Red Dot

Erini Lambrides, Rebecca Larson, Taylor Hutchison, Pablo Arrabal Haro, Bingjie Wang, Brian Welch, Dale D. Kocevski, Chris T. Richardson, Casey Papovich, Jonathan R. Trump, Sarah E. I. Bosman, Jane R. Rigby, Steven L. Finkelstein, Guillermo Barro, Jacqueline Antwi-Danso, Arianna Long, Anthony J. Taylor, Jenna Cann, Jeffrey McKaig, Anton M. Koekemoer, Nikko J. Cleri, Hollis B. Akins, Mic B. Bagley, Danielle A. Berg, Volker Bromm, John Chisholm, Katherine Chworowsky, Sadie Coffin, M. C. Cooper, Olivia Cooper, Isa Cox, Mark Dickinson, Henry C. Ferguson, Maximilien Franco, Jonathan P. Gardner, Norman A. Grogin, Michaela Hirschmann, Marc Huertas-Company, Intae Jung, Jeyhan S. Kartaltepe, Gourav P. Khullar, Ray A. Lucas, Elizabeth J. McGrath, Alexa M. Morales, Grace M. Olivier, Óscar A. Chávez Ortiz, Pablo G. Pérez-González, Norbert Pirzkal, Rachel S. Somerville, Brittany Vanderhoof, Benjamin J. Weiner, L. Y. Aaron Yung, Jorge A. Zavala

Theme match 5/5

Digest

THRILS spectroscopy of the z~7 Little Red Dot THRILS_46403 (CEERS-10444/RUBIES_49140) reveals bona fide AGN tracers: multiple Fe lines including a 4.5σ [Fe VII] and several [Fe II], plus an auroral [N II] detection at 3.1σ. Three Balmer lines show broad emission with superposed narrow absorption whose small widths and depths imply a partially covering absorber at or beyond the broad-line region. Electron-temperature diagnostics indicate O++ is markedly hotter than N+ across densities, pointing to a powerful, hard central ionizing source. Together these features establish multiply ionized iron emission from an accreting SMBH within the first 800 Myr and suggest direct sight-lines from the disk to gas at or beyond the BLR.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 1: Inspect the 2D and 1D THRILS spectra to verify the [Fe II] suite near the Hβ–[O III] region, the isolated [Fe VII] feature, and the tentative auroral [N II]; use the multiple negative traces to assess sky/systematic residuals and line IDs.
Figure 2: Examine the multi-component fits to Hβ, [O III], and Hα to see the separation of broad emission from the narrow absorption; note where degeneracies arise (e.g., absorption trough near line center) and how they affect inferred BLR widths and narrow-line fluxes.
Figure 3: Compare O++ and N+ temperature curves to visualize the strong Te gradient; relate the elevated O++ temperatures to the hardness of the ionizing spectrum and to the critical density line marked for [Fe VII].
Figure 4: Check the single-line fits establishing [Fe VII] at 4.5σ and auroral [N II] at 3.1σ; confirm centroid alignment with the systemic redshift and assess whether neighboring features or skylines could mimic these detections.

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2509.07611v1

Balmer Absorption in Iron Low-Ionization Broad Absorption Line Quasars

Karen M. Leighly, Sarah C. Gallagher, Hyunseop Choi, Donald M. Terndrup, Julianna R. Voelker, Gordon T. Richards, Leah K. Morabito

Theme match 5/5

Digest

Analyzes Balmer absorption in 14 FeLoBAL quasars (8 new), measuring velocities, widths, and apparent optical depths, and correcting for partial covering to infer true H(n=2) columns. Finds only a weak Eddington ratio–outflow speed trend because most objects are low‑speed “loitering” outflows; dN/dv peaks at low velocities and anticorrelates with luminosity and Eddington ratio. Reports a correlation between Balmer-line width and the optical–IR slope αoi, tying absorber kinematics to SED/accretion state. Notes parallels with Little Red Dots—V‑shaped continua, steep reddening with a scattered blue component, weak hot dust, and X‑ray weakness—hinting at shared conditions that elevate the n=2 population.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Balmer series profiles (Hα/Hβ/Hγ) with partial‑covering fits: inspect Balmer decrement departures to quantify covering fraction and derive the true H(n=2) column density.
Eddington ratio versus outflow speed scatter plot: verify the concentration of points at |v| < 2000 km s−1 (loitering regime) and the resulting weak correlation.
dN/dv as a function of velocity, split by luminosity/Eddington bins: check that the strongest absorption occurs at the lowest speeds and in the lowest‑L, lowest‑Edd objects.
Absorption-line width versus αoi: assess the significance and slope of the correlation linking kinematics to SED shape/accretion rate.
Rest‑optical/near‑IR SED or spectra comparison: identify steep reddening, scattered blue continuum, and lack of hot‑dust bump; contrast FeLoBALQs with representative LRD spectra.

Tags

2509.07100v1

Active galactic nuclei-heated dust revealed in "little red dots"

I. Delvecchio, E. Daddi, B. Magnelli, D. Elbaz, M. Giavalisco, A. Traina, G. Lanzuisi, H. B. Akins, S. Belli, C. M. Casey, F. Gentile, C. Gruppioni, F. Pozzi, G. Zamorani

Theme match 5/5

Digest

This Letter median-stacks NIRCam, MIRI, and ALMA imaging for 302 photometrically selected little red dots across CEERS, JADES(+SMILES), and PRIMER (z≈2–11; median z≈6.2). The stacked SED rises to ≈3 µm in the rest frame, and CIGALE fits require a dusty AGN component in most (≳50%) LRDs; combined with ALMA non-detections and deep Chandra stack null results, this points to Compton-thick gas (NH>3×10^24 cm^-2) likely confined within Rsub≈0.1 pc. The inferred geometry leaves optical/UV and broad-line emission largely unobscured, matching blue UV slopes and strong Balmer features. While LRDs are heterogeneous, the prevalence of AGN-heated dust implies obscured black-hole growth is common in this population.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Fig. 1 stacked cutouts (NIRCam→MIRI→ALMA): verify the band-by-band detections (S/N>3 in all but MIRI/F2550W) and that emission is unresolved compared to the PSF, highlighting the emergence of MIR flux relative to the NIRCam bands.
Fig. 2 SED fits (CIGALE): compare galaxy-only versus galaxy+AGN solutions to see why MIRI points demand hot dust; inspect the multi-temperature greybody decomposition and the mismatch with the normalized BH-star SED.
Table 2 stacked photometry: check the measured fluxes and errors used in the SED fit, especially the strength of the 7.7–21 µm stacks and the ALMA/B6 upper limit constraining cool dust.
Fig. 4 redshift distribution and filter-convolution: assess rest-frame coverage around 1–3 µm at the sample’s median z≈6.2, confirming the lever arm that isolates hot-dust emission.

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2509.10638v1

Radiation GRMHD Models of Accretion onto Stellar-Mass Black Holes: II. Super-Eddington Accretion

Lizhong Zhang, James M. Stone, Christopher J. White, Shane W. Davis, Yan-Fei Jiang, Patrick D. Mullen

Theme match 3/5

Digest

A radiation–GRMHD suite with angle-discretized transport follows super‑Eddington inflow across accretion rates, spins a*≈0.3–0.94, and single/double‑loop fields, finding robust, radiation‑pressure supported thick disks. Inner‑disk radiation drives powerful outflows that carve conical funnels, trap photons, and keep radiative efficiencies low while thermal transport is dominated by advection. Angular momentum is carried mainly by Maxwell stress; jets occur in weak and strong modes, with strong jets (net vertical flux + high spin) evacuating the funnel and enabling geometrically beamed escape, whereas weak jets leave the funnel clogged and dimmer—implications for ULXs and little red dots. Spiral density waves appear in the plunging region, adding structure to the inner flow.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

3D renderings of model E88‑a3‑LR (gas density + magnetic streamlines; radiation energy density): inspect jet collimation, funnel opening angle, and how helical fields coincide with the evacuated core that enables beamed escape.
Table 1 (model comparison): read off Δz_disk@10 rg, inflow‑equilibrium radius r_eq, photon‑trapping radius r_tr, and the power‑law fits for thermal/magnetic pressure and Maxwell/Reynolds stresses to see how spin and topology shift trapping and transport.
Radial transport budgets (time/φ averages): identify where radiation advection overtakes diffusion and quantify the Maxwell‑dominated angular‑momentum flux versus subdominant turbulent Reynolds stress.
Funnel optical depth and radiation flux contrasts between strong‑jet and weak‑jet runs: verify when net vertical flux + high spin clear the funnel, producing narrow beaming and higher apparent luminosity versus wind‑obscured funnels.
Plunging‑region maps: track spiral density waves inside r_ISCO, their pattern relative to inflow, and their imprint on variability channels.

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2509.09770v1

Early Stages of Dusty Tori: The First Infrared Spectra from a Highly Multiscale Quasar Simulation

Jaeden Bardati, Philip F. Hopkins, Gordon T. Richards

Theme match 3/5

Digest

First IR spectra from a fully self-consistent, cosmological-to-sub-sublimation quasar simulation (post-processed with SKIRT) show that the emission is dominated by a torus-like structure built from a highly magnetized, turbulence-supported outer accretion disk plus dusty gas tidally stripped from the ISM. In this early phase the nucleus is buried and Compton-thick, and the escaping near–mid-IR luminosity varies by nearly an order of magnitude with sightline, driven largely by extinction in an inflowing cold dusty stream. Self-absorption within the torus cools the SED and suppresses silicate emission, while reprocessing by the surrounding ISM imprints prominent silicate absorption; sublimation zones stratified by grain size/composition yield intrinsically varied extinction curves that emerge grayed after multiple scatterings. Clearing biconical cavities in later stages preserves MIR anisotropy and silicate features, implying a buried, IR-bright phase early in dusty starburst quasar evolution.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 1: Inspect the RGB wavelength maps within ~1 pc (pre–self-absorption) to see the torus-like emitter formed by the magnetized outer disk plus tidally torn ISM, and note polar clumps/streams and strong azimuthal asymmetry that break a smooth-torus picture.
Figure 2: Compare intrinsic vs emergent spectra at 1 pc and the sightline spread to confirm a hot-dust peak, heavy optical/UV attenuation, and persistent MIR anisotropy (factor-of-few), consistent with a buried Compton-thick phase.
Figure 3: Use the component decomposition (direct, scattered, dust re-emission with/without scattering) to verify that optical/UV is scattering-dominated and that dust self-absorption both cools the IR SED and weakens silicate emission relative to the no–self-absorption case.
Figure 4: Examine the escaped bolometric luminosity vs orientation (defined by the 0.1 pc angular-momentum axis) and the max/min/mean spectra to identify the inflowing cold dusty stream as the primary source of sightline-dependent extinction affecting both optical and IR.

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2509.07064v1

GA-NIFS: an extended [OIII] halo around the sub-Eddington quasar J1342+0928 at z=7.54

Bartolomeo Trefoloni, Stefano Carniani, Elena Bertola, Giacomo Venturi, Sandra Zamora, Eleonora Parlanti, Santiago Arribas, Andrew Bunker, Stéphane Charlot, Francesco D'Eugenio, Peter Jakobsen, Roberto Maiolino, Michele Perna, Bruno Rodríguez Del Pino, Hannah Übler, Chris J. Willott, Torsten Böker, Giovanni Cresci, Isabella Lamperti, Madeline Marshall, Pablo G. Pérez-González

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Digest

JWST/NIRSpec IFS (GA-NIFS) observations of ULAS J1342+0928 (z=7.54) combine prism (R~100) and high-resolution grating (R~2700) to map rest-UV–optical emission and kinematics. The prism cube reveals [O III] λ5007 extended over ~7 kpc—well beyond typical galaxy sizes—consistent with a relic from a past outflow, while the grating data resolve a compact (≤0.6 kpc) nuclear ionized outflow with a mass-loss rate of 50–300 Msun/yr, comparable to the host SFR of 85–545 Msun/yr. Accretion-disk modeling yields log(MBH/Msun)=9.2±0.2 and log(Lbol/erg s−1)=46.8±0.1, implying λEdd≈0.4 and pointing to sub-Eddington growth at the epoch of reionization. The most distant BLR ratios (Fe II UV/Mg II and Fe II opt/Hβ) indicate early metal enrichment; the outflow-rate range is chiefly set by uncertain ne.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

[O III] λ5007 narrow-band map and surface-brightness profile from the prism cube to verify the ~7 kpc halo extent, morphology, and any asymmetry suggestive of a relic outflow shell.
Velocity and dispersion maps (and W80) from the high-resolution [O III]/Hβ fits to isolate the ≤0.6 kpc nuclear outflow, its geometry, and peak velocities used in the mass-outflow calculation.
Integrated rest-UV–optical spectrum with line decompositions (Mg II, Hβ, [O III]) showing the Fe II templates and the BLR ratio measurements that support early metal enrichment.
Continuum SED and accretion-disk fit across the JWST coverage demonstrating how MBH and Lbol are constrained and yielding λEdd≈0.4; check residuals and parameter priors.
Outflow energetics panel comparing ionized mass-outflow rate (50–300 Msun/yr) versus assumed electron density alongside the host SFR (85–545 Msun/yr) to gauge potential quenching impact.