Weekly issue

Week 10, 2025

Mar 3–9, 2025

Week 10, 2025 includes 7 curated papers, centered on high-z, LRD, QSO.

2503.02059v1

A confirmed deficit of hot and cold dust emission in the most luminous Little Red Dots

David J. Setton, Jenny E. Greene, Justin S. Spilker, Christina C. Williams, Ivo Labbe, Yilun Ma, Bingjie Wang, Katherine E. Whitaker, Joel Leja, Anna de Graaff, Stacey Alberts, Rachel Bezanson, Leindert A. Boogaard, Gabriel Brammer, Sam E. Cutler, Nikko J. Cleri, Olivia R. Cooper, Pratika Dayal, Seiji Fujimoto, Lukas J. Furtak, Andy D. Goulding, Michaela Hirschmann, Vasily Kokorev, Michael V. Maseda, Ian McConachie, Jorryt Matthee, Tim B. Miller, Rohan P. Naidu, Pascal A. Oesch, Richard Pan, Sedona H. Price, Katherine A. Suess, John R. Weaver, Mengyuan Xiao, Yunchong Zhang, Adi Zitrin

Theme match 5/5

Digest

Deep MIRI imaging plus new ALMA continuum and [C II] spectroscopy on two luminous LRDs at z=3.1 (A2744-45924) and z=4.47 (RUBIES-BLAGN-1) set the tightest IR constraints yet. Rest-frame 1–4 μm detections show a flat IR slope, excluding hot (T≳500 K) dust, while far-IR non-detections exclude a cold (T≲75 K) component and typical [C II]-bright dusty starbursts. Empirical maximal SEDs require log(L_IR/L_sun) ≲ 12.2 (3σ), in strong tension with energy-balance predictions from reddened galaxy, AGN, or composite fits. The authors favor intrinsically red LRD SEDs over heavily dust-reddened blue engines, reshaping how these compact sources are interpreted.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 2: Inspect the side-by-side cutouts to see mid-IR detections but absent ALMA continuum and [C II] for both A2744-45924 and RUBIES-BLAGN-1—this visually anchors the dust and line non-detections driving the conclusions.
Figure 3: Compare IR SED data/limits against galaxy-only and composite (SKIRTOR torus + Draine cold dust) predictions; note how both hot and cold components overshoot the new MIRI/ALMA constraints.
Figure 4: Trace the allowed contribution of single-temperature modified blackbodies (20–800 K); observe how rest-frame ≈1–4 μm rules out hot dust and ALMA/Herschel limits cap any warm/cold components, with the Akins et al. stacked LRD SED shown for context.
Figure 1: Review the energy-balance premise using A2744-45924—models that redden an intrinsically blue engine predict substantial FIR re-emission that is incompatible with the new limits.

Tags

2503.01945v1

No [CII] or dust detection in two Little Red Dots at z$_{\rm spec}$ > 7

Mengyuan Xiao, Pascal A. Oesch, Longji Bing, David Elbaz, Jorryt Matthee, Yoshinobu Fudamoto, Seiji Fujimoto, Rui Marques-Chaves, Christina C. Williams, Miroslava Dessauges-Zavadsky, Francesco Valentino, Gabriel Brammer, Alba Covelo-Paz, Emanuele Daddi, Johan P. U. Fynbo, Steven Gillman, Michele Ginolfi, Emma Giovinazzo, Jenny E. Greene, Qiusheng Gu, Garth Illingworth, Kohei Inayoshi, Vasily Kokorev, Romain A. Meyer, Rohan P. Naidu, Naveen A. Reddy, Daniel Schaerer, Alice Shapley, Mauro Stefanon, Charles L. Steinhardt, David J. Setton, Marianne Vestergaard, Tao Wang

Theme match 5/5

Digest

Two z_spec > 7 Little Red Dots in FRESCO GOODS-N (ID9094, ID2756) show v‑shape colors, compact morphologies, and broad Hβ (FWHM 2280±490 and 1070±240 km/s), marking them as Type‑I AGN candidates. Deep NOEMA follow-up finds no [CII] 158 μm or 1.3 mm continuum; a DSFG interpretation would have yielded strong detections (>16σ [CII] and >3σ 1.3 mm for ID9094; >5σ [CII] for ID2756). Using the 3σ FIR limits in UV–FIR SED fitting (with/without AGN) and comparison to the L_[CII]–SFR_tot relation, the data favor an AGN contribution, as a dust‑only model would require unusually high dust temperatures. The work shows FIR non‑detections can discriminate AGN‑dominated LRDs from DSFG impostors at z > 7, though a purely dusty origin cannot be fully excluded.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 1: Inspect NIRCam stamps and F410M grism spectra to see the point‑source morphologies and the decomposition of Hβ into narrow/broad components that set the quoted FWHM values for ID9094 and ID2756.
Figure 2: Check where ID9094/ID2756 fall relative to the LRD color–compactness cuts; this verifies they meet the v‑shape and compactness criteria used for selection.
Figure 3: Examine the NOEMA [CII] moment‑0 maps and 1.3 mm contours over the JWST RGB; confirm the lack of [CII] at the z_spec‑predicted frequency and the absence of continuum within the shown beam.
Figure 4: Compare SED fits with and without an AGN; note how the 3σ 1.3 mm upper limit forces unphysically high dust temperatures in the no‑AGN fit, while including an AGN yields a more plausible FIR shape.

Tags

2503.05537v1

Little Red Dots as the Very First Activity of Black Hole Growth

Kohei Inayoshi

Theme match 4/5

Digest

Using 341 Little Red Dots (39 with spectroscopic redshifts) compiled from JWST surveys, this paper models their occurrence across cosmic time. The counts peak at z ~ 6–8 and fall steeply by z < 4, well described by a log‑normal distribution interpreted as the first one or two accretion episodes of newborn seed black holes. Dense circumnuclear gas naturally explains broad Balmer-line absorption, X‑ray weakness, and brief super‑Eddington bursts that yield overmassive BHs relative to local relations. Summing recurrent episodes reproduces the global AGN abundance evolution ∝ (1+z)^(−5/2) and provides an analytic form for the LRD redshift dependence for future tests.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 1 (left): Inspect the redshift/time histogram and magenta log‑normal fit to locate the LRD peak near z ~ 6–8 and the rapid drop by z < 4; note the shaded incompleteness where the turnover enters F356W.
Figure 2 (left): Episode‑by‑episode AGN number densities (1st–4th) show LRDs tied to the earliest episodes; verify that the summed black curve matches observed AGN abundances (Ueda 2014) while matching the Kokorev/Kocevski LRD counts.
Figure 2 (right): Fraction of non‑LRDs versus redshift; compare the model transition after the first–second episodes with the Taylor (2024) constraint to see when systems cease to look like LRDs.
Figure 3: UV absolute‑magnitude distributions and occurrence rates for subsets; use the vertical threshold to gauge where flux limits start biasing the high‑z tail and confirm the log‑normal trend persists for brighter cuts.
Figure 4: Compare the preferred log‑normal occurrence model against merger‑driven decay curves to see why mergers alone cannot reproduce the steep decline.

Tags

2503.03547v1

Exploring the physical properties of Type II Quasar candidates at intermediate redshifts with CIGALE

P. A. C. Cunha, A. Humphrey, J. Brinchmann, A. Paulino-Afonso, L. Bisigello, M. Bolzonella, D. Vaz

Theme match 3/5

Digest

CIGALE SED fits are used to derive SFR, M*, AGN luminosity, and AGN fraction for 366 machine‑learned Type II quasar candidates in the redshift desert (median z≈1.1), then benchmarked against SPRITZ populations and literature samples. On the SFR–M* plane many candidates sit above the main sequence at their redshift, while a tail appears quenched, pointing to episodes of enhanced star formation alongside possible feedback or obscured SF. The inferred properties align with SPRITZ composite systems and AGN2, supporting their obscured‑AGN nature and validating machine‑learning selection beyond simple colour–colour cuts.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 1 (stacked SDSS spectrum): Check narrow high‑ionization [Ne V] and [O II] visibility and Gaussian fits to verify Type II line signatures and stacking S/N across rest‑frame coverage.
Figure 2 (frac_AGN trends): Inspect how M* and specific L_AGN/M vary with frac_AGN, and where sources cross the Leja et al. (2018) threshold—useful for identifying a high‑frac_AGN tail and typical host masses.
Figure 3 (SFR–M* plane): Quantify the fraction above the Schreiber et al. (2015) main sequence at z≈1.1 and compare offsets against zCOSMOS AGN2 contours and the SDSS control to see the elevated‑SFR locus.
Figure 4 (ΔSFR from MS): Compare ΔSFR distributions for the QSO2s versus Bongiorno et al. (2012) and Zakamska et al. (2003) to visualize both the starbursting and quenched tails relative to the main sequence scatter.

Tags

2503.03431v1

Self-Consistent JWST Census of Star Formation and AGN activity at z=5.5-13.5

Jordan C. J. D'Silva, Simon P. Driver, Claudia D. P. Lagos, Aaron S. G. Robotham, Nathan J. Adams, Christopher J. Conselice, Brenda Frye, Nimish P. Hathi, Thomas Harvey, Rafael Ortiz, Massimo Ricotti, Clayton Robertson, Ross M. Silver, Stephen M. Wilkins, Christopher N. A. Willmer, Rogier A. Windhorst, Seth H. Cohen, Rolf A. Jansen, Jake Summers, Anton M. Koekemoer, Dan Coe, Norman A. Grogin, Madeline A. Marshall, Mario Nonino, Nor Pirzkal, Russell E. Ryan,, Haojing Yan

Theme match 3/5

Digest

Combining ≈400 arcmin^2 of JWST imaging from PEARLS, CEERS, NGDEEP, JADES, and PRIMER, this work jointly fits galaxy and AGN components with EAZY+ProSpect for ≈3.9k galaxies at z=5.5–13.5 to build SMF, SFRF, and AGNLF in four bins. Integrating these functions shows a ~1 dex rise in the CSFH from z≈13.5→5.5, while the CAGNH also increases and tentatively does so more rapidly, implying early SMBH accretion can outpace stellar mass growth. The results are stitched to z<5 measurements to provide a continuous, self-consistent census spanning >13 Gyr. This anchors the early coevolution picture and constrains the AGN contribution around reionization.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Fig. 1 (pipeline calibration deltas): Quantifies median per-pixel magnitude shifts between JWST calibration/CRDS pmap versions by filter—use this to gauge systematic photometric floors that propagate into SMF/SFRF/AGNLF.
Fig. 2 (GAIA star masking): Shows the PSF-wing/radial profile modeling and chosen mask radius versus image depth; check how bright-star halos are suppressed and the impact on completeness near saturated stars.
Fig. 3 (ProFound vs SourceExtractor + astrometry): Compares F444W photometry and EPOCHS–PEARLS astrometric offsets; verify zero-point consistency and cross-survey alignment for the unified catalogs.
Fig. 4 (EAZY high‑z selection): Photometric-redshift comparison for CEERS EGS and JADES GOODS‑S; inspect where high‑z EAZY solutions pass cuts versus outliers along the equality line to assess contamination control.

Tags

2503.03870v1

The Convergence of Heavy and Light Seeds to Overmassive Black Holes at Cosmic Dawn

Haojie Hu, Kohei Inayoshi, Zoltan Haiman, Luis C. Ho, Ken Ohsuga

Theme match 2/5

Digest

A semi-analytic growth model tied to dark-matter halo assembly follows M_BH/M_star for both heavy and light seeds under feedback-limited, episodic super-Eddington accretion. Despite mass loss in winds, the ratio first increases and then converges to a universal ~0.1–0.3 set by the balance between nuclear gas feeding and star-formation efficiency, forming an attractor in the M_BH–M_star plane. On this attractor, overmassive BHs grow more slowly than their hosts while undermassive seeds catch up rapidly, erasing seed-memory by z~4–6. The model predicts that 10^5–10^6 Msun BHs at higher redshift that deviate from this trend would reveal their birth conditions.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 1 (left): Compare light vs heavy seed tracks across different halo merger histories against pre-JWST and JWST SMBH compilations to see how the model envelopes bracket observed BH masses and how halo growth rate drives early overmassiveness.
Figure 1 (right): Inspect the evolution of M_BH/M_star for both seed classes relative to local benchmarks and the stated maximum line to see the approach toward the universal ~0.1–0.3 ratio and when tracks diverge/converge with redshift.
Figure 2: Follow the vector-field flow in the M_BH–M_star plane at four epochs and the marked transition from super- to sub-Eddington accretion; this visualizes the attractor direction and where heavy vs light seeds accelerate or decelerate.
Figure 3: Contrast SP1–SP3 feedback prescriptions to see how stronger/weaker outflows reshape the flow field and shift the convergence path and timescale toward the universal ratio.
Figure 4: Use the probabilistic track contours for light/heavy seeds (with parameter spreads) and the overplotted JWST SMBHs to assess how rapidly systems approach the attractor across mass scales at successive redshifts.

Tags

2503.02942v1

Spectroscopic AGN survey at $z$ $\sim$ 2 with NTT/SOFI for GRAVITY+ observations

D. J. D. Santos, T. Shimizu, R. Davies, Y. Cao, J. Dexter, P. T. de Zeeuw, F. Eisenhauer, N. M. Förster-Schreiber, H. Feuchtgruber, R. Genzel, S. Gillessen, L. Kuhn, D. Lutz, T. Ott, S. Rabien, J. Shangguan, E. Sturm, L. J. Tacconi

Theme match 2/5

Digest

NTT/SOFI K-band spectroscopy vets 29 z≈2 type 1 quasars for GRAVITY+, measuring Hα fluxes and Balmer-line shapes to preview BLR kinematics. The Balmer profiles are strongly non-Gaussian with narrow cores plus broad wings, consistent with rotation plus turbulence or a two-zone BLR; two objects show tentative radial-motion dominance. Low FWHM/σ ratios yield small Hα virial factors, cautioning that single-epoch mass scalings can under-estimate MBH for these profiles. Predicted differential-phase signals guide VLTI/GRAVITY+ strategies to secure dynamical BLR masses at cosmic noon.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 1 (line decompositions across Hα and Hβ): Inspect Fe II blends, [O III], and [N II] features and the narrow-core/broad-wing structure in objects like QBQS J051411.75-190139.4 and SDSS J220245.60-024407.1; this shows why single-Gaussian fits fail and motivates the BLR modeling used for GRAVITY+ predictions.
Figure 2 (FWHM/σ vs FWHM): Most points lie below the Gaussian limit (2.35), aligning better with rotationally broadened Lorentzians; this plot visually links line shape to kinematics and explains the small Hα virial factors derived.
Figure 3 (L(Hα)/L(Hβ) vs L(Hβ)): Use the Balmer luminosity ratio to check internal consistency of single vs double-Gaussian fits and to gauge reddening/geometry effects; note the removal of the two exceptions where Hβ could not match Hα’s line-shape model.
Figure 4 (Lbol vs MBH with Eddington-ratio tracks): See where the sample sits relative to Suh+2020 and WISSH quasars and how Woo+2015 σ-based masses position many sources at moderate to high λEdd, underscoring their suitability for GRAVITY+ phase signals.