Weekly archive
LRDigestWeekly digests of little red dots and JWST-selected AGN papers, with curated reading notes and archive pages.
654 indexed papers · 430 research notes
A DESI DR1 line-selected search identifies eight compact z=0.20–0.44 LRD candidates with broad, steep-decrement Balmer emission, low-excitation spectra, and generally weak multi-year variability, extending detailed LRD tests to the nearby Universe.
JWST/MIRI-MRS-informed SED fits to the single z=4.601 Hot DOG W2246-0526 favor an added hot-dust component interpreted as polar dust. This changes inferred AGN luminosity, but its geometry and physical association with an outflow remain model-dependent.
UV-to-optical fitting of one z=3.55 little red dot, The Cliff, admits a BH* envelope plus low-mass, dusty, metal-poor host. The result depends materially on Balmer-absorption and dust prescriptions, while AGN UV leakage remains unconstrained.
eROSITA-triggered monitoring of HE 1237-2252/J1240−2309 links a changing-look transition to intrinsic accretion-rate recovery and an evolving two-component Balmer-line profile. A diskline-like component strengthens with UV flux, while the proposed corona/illumination mechanism remains interpretive.
JWST/MIRI-MRS resolves a warm-H₂ outflow in the composite ULIRG F10565+2448: it is hotter than the disk but apparently sub-escape-speed, while a faster unresolved ionized component and localized shock candidates support multiphase feedback.
JWST/MIRI-MRS mapping of seven nearby radio-loud AGN links elevated warm-H2 excitation and broadened multiphase gas to radio-jet environments, including transverse regions. The authors interpret the correlations as predominantly jet-driven shocks, while recognizing source-dependent exceptions.
For the single $M_\star\sim10^{10}\,M_\odot$ host GAMA 376183, NuSTAR and multiwavelength data support a heavily obscured, rapidly accreting AGN in a disturbed system; the proposed merger-triggered starburst/accretion connection remains suggestive rather than demonstrated.
Multi-epoch JWST/NIRSpec spectra of one z~7 little red dot show coordinated continuum, broad-Balmer, and [O III] changes over ~13 rest-frame days. If intrinsic, the variability ties at least some narrow-line gas to the central engine and disfavors complete dense-gas coverage.
JWST IFU spectroscopy of NGC 7582 separates rotating circumnuclear-disk gas from an AGN bicone by ionisation potential and line-profile decomposition, finding distinct kinematic axes and broader outflow lines; mixed-ionisation tracers require two components.
Hebe’s strong He II emission can be matched by either a near-maximal Pop III burst or an accreting 10^4–10^5 M⊙ black hole, but the authors favor Pop III stars because the inferred burst mass remains physically plausible.
Five DESI DR1 sources at z=0.2–0.4 reproduce LRD-like V-shaped SEDs and broad Balmer lines, but their AGN-like line ratios and substantially larger hosts make an evolutionary connection to z>4 LRDs plausible rather than established.
Using southern-sky multi-band photometry and quasar-versus-brown-dwarf SED fitting, the authors compile 6,104 z=4.5–7 quasar candidates. Three of six bright, visually screened follow-up targets are confirmed at z>5, but catalog-wide purity remains weakly constrained.
Across a complete Hα-flux-limited GOODS-N sample, 18 LRDs and nine other broad-Hα emitters show no detected continuum, line-flux, or line-shape variability over 139–220 rest-frame days, challenging their interpretation as ordinary broad-line AGN.
Across ∼48,000 photometric and ∼5,000 spectroscopic galaxies, the authors find LRD-like colour, compactness, and broad-Hα properties vary continuously, arguing that most LRDs are an extreme tail rather than a discrete class; only ∼3% show very strong Balmer breaks.
JWST/NIRSpec-IFU spectroscopy of the single z=3.55 Little Red Dot The Cliff yields a very low narrow-line metallicity, Z=0.017±0.004 Z⊙, while broad Hβ-based virial estimates place its black hole above local host-scaling expectations.
Medium-resolution JWST/NIRSpec data spatially separate an LRD-like AGN and its host at z=6.64, revealing exceptionally broad ionised gas consistent with AGN driving but a low inferred mass-loading factor and therefore limited immediate star-formation impact.
Ultra-deep JWST/NIRSpec spectra of two Abell 2744 little red dots resolve a broad Lyα component in z=7.0364 Abell2744-QSO1. The authors argue its comparatively modest shift favors a clumpy, rather than uniform, neutral envelope and an ionized local environment.
JWST/NIRSpec FUV spectroscopy of the single z=7.04 LRD Abell2744-QSO1 resolves extended narrow and unresolved broad Lyα components. The authors interpret broad Lyα/Balmer ratios as evidence for lower-column-density sightlines through otherwise dense, clumpy BLR-scale gas.
A five-stage extraction and deblending pipeline yields reliable slitless-spectroscopic measurements for 461 Euclid Q1 lens candidates, including 178 source–deflector redshift pairs. Dual grism orientations strengthen validation, but incomplete deflector spectroscopy and unmeasured real-data deblending performance constrain inference.
PAN-BH*-1 is a single z=1.731 Little Red Dot at cosmic noon with an extreme Balmer break, compact red continuum, and broad Hα absorption. Its data are consistent with—but do not establish—a thick, rotating photospheric disk wind.
XRISM Resolve spectroscopy of the crowded Galactic-centre field isolates narrow iron-line emission attributed to the black-hole candidate MAXI J1744-294, including static highly ionized gas and atypical features consistent with blueshifted material, though plasma origin and background systematics remain unresolved.
In a 140 deg² eROSITA field, the authors identify eight z=0.3–0.8/1 quasars with inferred M•/M⋆>5%. Their abundance supports recurrent black-hole/host offsets among rapidly accreting AGN, but single-epoch masses and often upper-limited host masses temper the conclusion.
In 32 AGN spanning LRDs, LBDs and X-ray detections, broad Hα profiles do not generally require electron scattering: Lorentzian or multi-Gaussian alternatives often fit comparably, while BLR stratification and stacking can generate exponential-looking wings.
In 18 z≈3–7 broad-Hα emitters, Balmer cores progress from narrow emission to P-Cygni-like and absorption-dominated profiles as UV–optical colour reddens. The authors interpret this as changing envelope column density and optical depth, not purely dynamical line broadening.
A radio-loud quasar at z=1.715 has a ∼10,000 K curved UV continuum and broad lines, making it a plausible—but unconfirmed—low-redshift analogue of an LRD-to-quasar transition.
JWST IFU observations of 10 local Seyferts use PCA tomography of broad PAH bands to map dust-phase kinematics. The authors report neutral, larger PAHs sharing molecular and ionised-outflow signatures in NGC 5728 and NGC 7582, while 3.3 μm PAHs trace disks.
Forward-modeling broad-Hα selection in a JADES broad-line AGN sample at z≳4 yields an M_BH–M★ relation consistent in mean with local relations but with 0.63 dex intrinsic scatter, implying diverse early black-hole growth histories.
A new LRD-tailored atmosphere library finds that The Egg’s continuum curvature, weak 1.6-μm H− kink, and Ca II triplet jointly favor an exceptionally dilute photosphere, challenging hydrostatic interpretations and providing testable near-IR spectral diagnostics.
JWST/NIRSpec follow-up of CEERS extreme emission-line galaxies finds broad-line AGN contamination, but for spectroscopically extreme sources the narrow Hα component dominates. The authors therefore attribute the most extreme nebular emission primarily to young star formation, not AGN.
A 249-object JWST spectroscopic compilation argues that photometrically selected Little Red Dots are spectroscopically heterogeneous composites of accreting black holes and young stars, but its mass, duty-cycle, and Wolf–Rayet interpretations remain model-dependent.
Medium/high-resolution JWST/NIRSpec spectra of 11 z~4 little red dots separate broad and narrow Balmer emission, linking broad Hα to the optical continuum while [O III] tracks UV light. The authors infer rapidly accreting 10^6–10^8 M⊙ black holes and propose a clumpy envelope.
GNz7q at z=7.1899 combines a 10^7.55-M⊙, apparently super-Eddington black hole with a massive, rapidly star-forming host. The authors argue that its near-local BH-to-stellar mass ratio makes it a plausible progenitor channel for luminous z≈6 quasars.
JWST/NIRSpec spectra reveal a 1.4-μm water band in two of four measurable z≈2 little red dots, requiring a cool (<3,000 K) continuum component and favoring intrinsic cool emission for these objects over purely dust-reddened hot continua.
JWST/ASPIRE clustering across 25 z≈6.6 quasar fields associates UV-bright quasars with substantially more massive minimum host halos than [O III] emitters, but the inferred ≈Myr quasar lifetime has a highly asymmetric, large uncertainty.
Multi-line JWST/NIRSpec IFU spectroscopy moves dusty massive galaxy S1 from z=5.58 to z=3.2439, tracing the earlier single-line grism assignment to spectral overlap. ALMA continuum and revised SED fitting instead describe a compact, obscured, massive star-forming galaxy.
A two-object JWST comparison finds that a prototypical Little Red Dot and Little Blue Dot share broad, non-Gaussian Balmer emission, weak hot dust, and X-ray weakness, but differ sharply in helium emission and Balmer absorption.
Using empirical [O III]-matched host subtraction for 98 JWST/NIRSpec LRDs, the authors infer a red, dense-envelope central component that dominates rest-optical light. The conclusion depends critically on assigning all [O III] to the host and on stack-based decomposition.
Self-consistent radiative-transfer modelling of z>3 LRD-like JWST spectra supports accreting ∼10^6 M⊙ black holes embedded in low-dust, dense ionized cocoons. The authors infer mixed inflow/outflow geometry and reproduce continuum breaks, absorption, and electron-scattering line wings.
JWST/NIRSpec spectroscopy of 16 ALMA-selected HUDF faint SMGs finds dusty, massive z=1–4 galaxies with mostly obscured AGN classifications, yet star-formation, metallicity, and bulk-ISM properties broadly consistent with comparable high-redshift star-forming populations.
JWST NIRSpec/MIRI nuclear spectra of eight LLAGN plus Cen A associate decreasing [Ne V]-to-X-ray output below log(Lbol/LEdd)≈−3.5 with a UV-deficient ionizing SED, while finding warmer rotational H2 and predominantly nuclear silicate emission.
For 31 Balmer-break-selected z=6–10 galaxies, the authors infer a mean stellar age of 0.61±0.31 Gyr (95% CL) and limited average red-wavelength AGN flux. Their claimed early formation and one extreme age tension remain model-dependent.
R≈120,000 ESPRESSO spectroscopy resolves exceptionally weak H2 at z=4.24 into cold, dense and warmer components. The authors interpret the narrow component as a ~0.01-pc atomic-gas overdensity, demonstrating that trace H2 can reveal otherwise elusive small-scale structure.
Long-slit spectroscopy of Stephan’s Quintet separates NGC 7319’s rotating disk, ionized AGN outflow, and tidal bridge: the authors infer a ≤550 km s⁻¹ outflow peaking at 2.6 kpc, with tidal motions increasingly dominant beyond 2.4–6.3 kpc.
JWST spectroscopy identifies a lensed z=5.96 “pseudo-LRD” whose red optical colour is Hα-line driven, yet whose broad Hα supports a ∼3×10^6 M⊙ black hole embedded in a dusty, dense, very metal-poor starburst.
JWST/HST observations of the lensed z≈6.87 galaxy A2744-z7DLA reveal damped Lyα absorption plus a statistically preferred broad Hα component, supporting a gas-enshrouded broad-line AGN interpretation while its UV–optical continuum remains predominantly stellar.
Across 28 z=5–7.2 LRDs, UV-to-Hα behavior resembles young starbursts rather than unobscured AGN, while nine blue broad-line controls resemble Type 1 AGN. The authors therefore favor opaque black-hole envelopes, but the correlations do not uniquely establish the ionizing mechanism.
A single z=3.28 compact “X-Ray Dot” combines Little Red Dot-like optical spectra with luminous hard X-rays. The authors favor, but do not establish, a transitional gas-envelope geometry over unusual nuclear dust.
Five-epoch spectroscopy of three AGNs with A_V>50 mag finds broad-Hα behavior is not uniform: Mrk 268 varies at 4.3σ, consistent with direct BLR emission, whereas MCG -3-34-64 and UGC 5101 favor outflow and/or scattering contributions.
Using DESI DR2 C IV-forest cross-correlations, the authors measure isotropic BAO distances at z_eff=1.92 with quasars and z_eff=1.47 with ELGs. The QSO result is 4.2σ (3.0% distance precision); the ELG signal is 2.5σ.
JWST 3–28 μm nuclear spectroscopy of four low-luminosity AGN associates weak high-ionization emission, shock-like line ratios, altered PAH populations, and non-thermal H₂ excitation with feedback, while leaving the proposed jet connection indirect.
JWST/NIRSpec IFU data identify ionized-outflow signatures in 14 of 40 regions of massive, non-AGN star-forming systems at z≈3–9. The authors infer dusty, metal-enriched but gravitationally retained gas, implying redistribution rather than efficient ejective feedback.
New JWST/NIRSpec IFU spectroscopy classifies LAE2, ~30 kpc from the quenched z=3.064 galaxy GS10578, as an AGN, completing a three-AGN environment; LAE1 is instead plausibly Lyα light scattered from LAE2.
This is a survey proposal, not a new AGN measurement: it argues that repeat optical MOS spectroscopy of >50 million multi-selected candidates to z~6.5 could quantify obscuration demographics while exposing selection biases among obscured populations.
JWST/NIRSpec disc fits for eight luminous z≥5.9 quasars yield a sub-Eddington distribution, ⟨log λEdd⟩=−0.86. The authors argue that self-consistent disc luminosities and masses reduce apparent super-Eddington incidence relative to conventional single-epoch estimates.
Using JWST/NIRSpec prism spectra, the authors find that strong C III] emission is common among 61 galaxies at z=5–7 and often coincides with AGN indicators, but upper limits and prism resolution leave many classifications provisional.
![Figure 1 from Shedding the envelope: JWST reveals a kiloparsec-scale [OIII]-weak Balmer shell around a z=7.64 quasar](/lrdigest/research/figures/2512.15881v1/figure-1-1.png?v=9c4c172c8f786a6a)
JWST/NIRSpec IFU data reveal Hβ emission to ~1.8 kpc around the z=7.64 quasar J0313−1806 but no significant [O III]. The authors favor dense, clumpy fossil-outflow gas, while the single-object data leave its geometry and evolutionary interpretation uncertain.
JWST/NIRSpec spectroscopy of 118 little red dots reveals a continuum–line sequence: red, curved Balmer-break SEDs give way to bluer, power-law-like systems. A galaxy plus enshrouded-black-hole model can reproduce the trend, but its physical decomposition remains non-unique.
Presents a NIRSpec/IFU reduction that exploits the red signal on NRS2 for medium‑resolution gratings, effectively doubling the usable wavelength coverage and recovering Hα beyond the nominal range; the authors also note the exposure‑time trade‑off when using adjacent dispersers. Applied to five z≈2 quasars with reverberation‑mapped MBH, the extended cubes enable joint Hβ–Hα measurements at R≈1000. Hβ‑based single‑epoch masses best match RM, while Hα recipes show ≈0.5 dex larger scatter; for the least‑massive, high‑λEdd object (MBH,RM≈10^7.5 M⊙, λEdd=0.8) all SE estimators overpredict by ~1 dex, suggesting a bias at high accretion. The work delivers the first high‑z SE calibrations from Hβ and Hα for the newfound early‑BH population, with uncertainties still limited by sample size.
ALMA CH–H2O absorption toward two lensed quasars finds no significant differential velocity and, with independent μ bounds, limits |Δα/α| to 0.55 ppm at zabs=0.88582, a sub-ppm cosmological constraint.
THRILS delivers deep JWST/NIRSpec G395M spectroscopy in two pointings, yielding 89 measured redshifts and empirical magnitude thresholds. Its >8-hour integrations expose faint lines inaccessible to shallower EGS spectroscopy, enabling targeted follow-up rather than population-level physical conclusions.