Weekly issue

Week 19, 2025

May 5–11, 2025

Week 19, 2025 includes 11 curated papers, centered on LRD, spectroscopy, high-z.

2505.06965v1

Black Hole Envelopes in Little Red Dots

Daisaburo Kido, Kunihito Ioka, Kenta Hotokezaka, Kohei Inayoshi, Christopher M. Irwin

Theme match 5/5

Digest

Proposes that little red dots host super-Eddington black holes wrapped in a massive, optically thick envelope that gravitationally confines otherwise destructive winds, effectively making outflows a no-go. The envelope radiates near the system Eddington limit with a photosphere at 5000–7000 K, naturally producing the red optical continuum and the hallmark V-shaped SED while explaining weak X-ray/radio and low short-term variability. A sustained ISM infall of ~1 M_sun/yr feeds the envelope, and a photospheric radius ~0.01 pc sets year-scale variability, linking LRD nuclear structure to Hayashi-limit physics. The envelope both regulates feedback and provides a reservoir enabling rapid early BH growth.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 1 — BH mass–stellar mass vs the too-strong-feedback line: inspect where LRDs fall relative to the gold criterion from eq. (11) to see that unconfined super-Eddington winds would disrupt many systems, motivating the need for a confining envelope; note the two X-ray detections marked with X.
Figure 2 — Schematic of the BH envelope: use this to internalize the geometry and energy flow—radiation/convection transport, Eddington-limited luminosity set by ṁ_BH, and external ISM inflow—clarifying why large-scale winds are suppressed.
Figure 3 — Envelope mass–radius viability: read the red (minimum bound mass) and green (maximum mass from Eddington) curves and the blue T_ph track to locate the allowed, gravitationally bound solutions; note convergence toward a Hayashi-like track and compare with the Ulmer (1998) curve that becomes unbound.
Figure 4 — Envelope mass vs effective temperature for a fixed BH mass: check how convection efficiency shifts the locus and where T_eff ≈ 5–7 kK sits to gauge the envelope mass required to reproduce LRD continua.

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2505.05556v1

Super-Eddington accretion in high-redshift quasar hosts: Black-hole driven outflows, galaxy quenching, and the nature of little red dots

Giada Quadri, Alessandro Trinca, Alessandro Lupi, Monica Colpi, Marta Volonteri

Theme match 5/5

Digest

Zoom-in cosmological simulations of a quasar host including super-Eddington accretion track how MBH feedback shapes gas, star formation, and emergent spectra. Outflows usually vent perpendicular to the disc and only moderately suppress the SFR, but after rapid super-Eddington growth the galaxy spends ≈10% of its lifetime in a distinct quenched state. This phase culminates in a powerful jet+disc-wind event that couples to the disc and excavates a central cavity. Across its history the system’s spectra can look like little red dots or quenched galaxies, implying both are transient stages in early quasar hosts.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 1 — Use the grey-shaded super-/near-Eddington intervals to link BH-mass jumps (purple, ×10^3) with drops in H2/HI and total gas; identify when fuel depletion precedes the quenched phase.
Figure 2 — Compare the simulated SFR track to CEERS and GLASS main-sequence fits to spot the ≈10% lifetime downturn; measure how far below the sequences the system falls during quenching.
Figure 3 — Read the energy budget: when MBH kinetic power spikes past stellar kinetic/radiative output, flag the feedback episode that triggers quenching; cross-check its timing with Figures 1–2.
Figure 4 — Inspect gas vs. stars maps across epochs to see disc disruption and the expanding low-density bubble centered on the MBH; assess outflow geometry (perpendicular to the disc) and the size of the excavated central cavity.

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2505.04826v1

Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs) XXII. Chandra observations of narrow-line quasar candidates at z>6

K. Iwasawa, R. Gilli, F. Vito, Y. Matsuoka, M. Onoue, M. A. Strauss, N. Kashikawa, Y. Toba, K. Shimasaku, K. Inayoshi, T. Nagao, N. Kawanaka, J. D. Silverman, T. Izumi, K. Kohno, Y. Ueda

Theme match 5/5

Digest

Chandra followed up four z>6 SHELLQs narrow-line quasar candidates chosen for luminous Lyα and faint UV continua, and found no X-ray detections, placing L2–10 keV < 2×10^44 erg/s (2σ; Γ=2). JWST/NIRSpec reveals weak broad Balmer bases beneath narrow cores, while strong [O III] would predict Lx ≈ 10^45 erg/s from low‑z scaling, in stark tension with the Chandra limits. The authors argue for heavily buried nuclei—either Compton-thick columns in dense ISM or an inclined, inflated inner disc in supercritical accretion—making these sources higher-luminosity analogs of JWST-selected broad-line AGN at reionization. The work clarifies how extreme Lyα–bright, UV-faint quasars can hide powerful engines early on.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 1: Use the CDFs to see how the four targets sit at FWHM(Lyα) < 500 km/s with extreme EW (>250 Å), quantifying their placement among SHELLQs outliers.
Figure 2: Inspect where the four circled targets lie as >2σ outliers in M1450 vs L(Lyα), highlighting their suppressed UV continua at fixed Lyα luminosity compared to LAEs.
Figure 3: Examine the stacked Lyα profile’s weak red wing to gauge any broad component width and consider BLR/outflow/resonant-scattering contributions consistent with partial hiding of the BLR.
Figure 4: Check the 1–5 keV postage stamps to confirm non-detections within the 1″ circles and assess any nearby serendipitous sources or astrometric offsets that could affect upper limits.

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2505.04825v1

SHELLQs. Bridging the Gap: JWST Unveils Obscured Quasars in the Most Luminous Galaxies at z > 6

Yoshiki Matsuoka, Masafusa Onoue, Kazushi Iwasawa, Kentaro Aoki, Michael A. Strauss, John D. Silverman, Xuheng Ding, Camryn L. Phillips, Masayuki Akiyama, Junya Arita, Masatoshi Imanishi, Takuma Izumi, Nobunari Kashikawa, Toshihiro Kawaguchi, Satoshi Kikuta, Kotaro Kohno, Chien-Hsiu Lee, Tohru Nagao, Ayumi Takahashi, Yoshiki Toba

Theme match 5/5

Digest

From the SHELLQs wide-field UV survey, the team followed 13 z>6, Lyα-luminous galaxies with JWST/NIRSpec and uncovered obscured quasars. Seven of eleven narrow‑Lyα systems show broad H I Balmer and He I components—but not in [O III]—with Balmer decrements indicating mild obscuration (0<Av<3), identifying them as UV‑obscured counterparts of luminous EoR quasars. Virial lines imply MBH≈10^(7.8–9.1) Msun with sub‑Eddington to Eddington accretion; most BL sources are unresolved and display LRD‑like blue‑UV/red‑optical colors. The AGN incidence among similarly bright Lyα emitters (≥2×10^−8 Mpc^−3) is comparable to classical quasar densities, implying a substantial obscured SMBH population previously missed by UV‑bright surveys.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 1: Locate the 13 targets relative to classical quasars and JWST BHEs; note which open circles (our sample) are flagged as BL detections to see the luminosity/redshift regime that bridges LRD/BHEs and UV‑bright QSOs.
Figure 2: Inspect G01–G05 NIRSpec spectra for broad Hβ/Hγ and He I atop narrow lines; use the insets to gauge Balmer decrements that yield Av≈0–3 and confirm the lack of broad [O III].
Figure 3: For G06–G10, verify BL profiles and the absence of broad forbidden lines; in G07, check the weak 4924 Å and 5756 Å features (possible Fe II/iron lines) as flagged by arrows.
Figure 4: For G11, Q01, Q02, compare BL signatures and search for the unidentified 5161 Å (and 5270 Å) lines in Q01/Q02 (candidate [Fe VII]); cross‑check that forbidden lines remain narrow while Balmer/He I are broad.
Line-profile panels (Figs. 2–4): Measure FWHM of Balmer/He I vs [O III] to see the BLR–NLR dichotomy that underpins the SMBH mass and obscuration inferences.

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2505.04609v1

CAPERS-LRD-z9: A Gas Enshrouded Little Red Dot Hosting a Broad-line AGN at z=9.288

Anthony J. Taylor, Vasily Kokorev, Dale D. Kocevski, Hollis B. Akins, Fergus Cullen, Mark Dickinson, Steven L. Finkelstein, Pablo Arrabal Haro, Volker Bromm, Mauro Giavalisco, Kohei Inayoshi, Stephanie Juneau, Gene C. K. Leung, Pablo G. Perez-Gonzalez, Rachel S. Somerville, Jonathan R. Trump, Ricardo O. Amorin, Guillermo Barro, Denis Burgarella, Madisyn Brooks, Adam Carnall, Caitlin M. Casey, Yingjie Cheng, John Chisholm, Katherine Chworowsky, Kelcey Davis, Callum T. Donnan, James S. Dunlop, Richard S. Ellis, Vital Fernandez, Seiji Fujimoto, Norman A. Grogin, Ansh R. Gupta, Nimish P. Hathi, Intae Jung, Michaela Hirschmann, Jeyhan S. Kartaltepe, Anton M. Koekemoer, Rebecca L. Larson, Ho-Hin Leung, Mario Llerena, Ray A. Lucas, Derek J. McLeod, Ross McLure, Lorenzo Napolitano, Casey Papovich, Thomas M. Stanton, Roberta Tripodi, Xin Wang, Stephen M. Wilkins, L. Y. Aaron Yung, Jorge A. Zavala

Theme match 5/5

Digest

CAPERS-LRD-z9 is a PRIMER-selected little red dot spectroscopically confirmed with NIRSpec/PRISM as a z=9.288 broad-line AGN via a ~3500 km s−1 Hβ plus narrow [O III] λλ4959,5007. The broad Hβ implies a canonical black-hole mass log(MBH/M⊙)=7.58±0.15 (allowing 6.65–8.50 with systematics). A pronounced Balmer break requires a dense (~10^10 cm−3) neutral-gas cocoon around the nucleus; SED modeling (CLOUDY+bagpipes) limits the host to M*<10^9 M⊙, hinting at MBH/M* possibly >5% and a UV continuum that may be AGN-dominated. Together, these properties push early BH growth scenarios toward massive seeds or super‑Eddington episodes within ≲500 Myr of cosmic time.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 1: Use the NIRCam/MIRI cutouts and slit overlay to verify the source’s compact, unresolved appearance and the PRISM extraction; in the 1D spectrum, note the Ly break, strong Balmer break, and the separation of broad Hβ from narrow [O III] features confirming the BLAGN nature at z=9.288.
Figure 2: Inspect the PRISM fits to Hβ+[O III]; the necessity of a broad Hβ component (FWHM ~3500 km s−1) anchors the MBH estimate, while the narrow [O III] doublet sets the systemic redshift and highlights the BLR–NLR dichotomy at z≈9.3.
Figure 3: Check the 2D surface-brightness modeling in F200W and F444W; point-source residuals show CAPERS-LRD-z9 is unresolved, implying pc-scale upper limits consistent with a nucleus-dominated light profile.
Figure 4: Examine the joint CLOUDY (dense, enshrouded AGN) + bagpipes (stellar UV) fit that reproduces the red-ward continuum/Balmer break and enforces M*<10^9 M⊙; also note the models’ failure to match strong [O III] λ4363, signaling extreme gas conditions not captured by the baseline setup.

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2505.02895v1

Abundant Population of Broad H$α$ Emitters in the GOODS-N Field Revealed by CONGRESS, FRESCO, and JADES

Junyu Zhang, Eiichi Egami, Fengwu Sun, Xiaojing Lin, Jianwei Lyu, Yongda Zhu, Pierluigi Rinaldi, Yang Sun, Andrew J. Bunker, Rachana Bhatawdekar, Jakob M. Helton, Roberto Maiolino, Zheng Ma, Brant Robertson, Sandro Tacchella, Giacomo Venturi, Christina C. Williams, Chris Willott

Theme match 5/5

Digest

Using JWST/NIRCam WFSS from FRESCO and CONGRESS plus JADES imaging, the authors conduct a GOODS‑N search for broad Hα at z≈3.7–6.5 and confirm 19 emitters at z≈4–5.5, including nine new ones. Their broad Hα LF aligns with other JWST BLAGN results, and virial BH masses with bolometric corrections imply ≈0.1 Eddington accretion and elevated MBH/M* relative to local relations. Color comparisons show LRD cuts miss 42% of these spectroscopic AGN—many lack the steep rest‑optical red slope—and average SEDs indicate some LRD red slopes are line‑boosted. Notably, 68% of color‑selected LRDs with Hα detections lack broad lines in the grism data, potentially due to sensitivity limits, underscoring the LRD population’s mixed nature.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 1: Inspect the multi-component Hα+[N II] fits source-by-source to verify the broad Hα component (FWHM>1000 km/s), the relative narrow/broad decomposition, and residuals that establish BLR detections.
Figure 2: Use the false‑color stamps to judge compactness and rest‑color diversity across the 19 AGN; compare F444W vs F356W emphasis (FRESCO vs CONGRESS) to see which objects lack the very red rest‑optical slopes typical of color‑selected LRDs.
Figure 3: Check the spatial distribution of confirmed broad‑line AGN against the JADES/FRESCO/CONGRESS footprints and redshift color‑coding to assess survey coverage and any apparent clustering within GOODS‑N.
Figure 4: Examine [O III] profiles for the three showcased objects to confirm the absence of comparably broad [O III] wings—supporting that line broadening is from the BLR in Hα rather than strong NLR outflows—and to validate systemic redshifts used in Hα modeling.

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2505.06359v1

JWST/NIRSpec Observations of High Ionization Emission Lines in Galaxies at High Redshift

Mengtao Tang, Daniel P. Stark, Adèle Plat, Anna Feltre, Harley Katz, Peter Senchyna, Charlotte A. Mason, Lily Whitler, Zuyi Chen, Michael W. Topping

Theme match 4/5

Digest

Deep NIRSpec R=2700 spectroscopy of 53 new z>4 galaxies, plus a census of 851 archival spectra, is used to track high-ionization UV lines. The team reports narrow NV λ1240 in two systems—CEERS‑7902 (z=6.98; an LRD with broad Hβ) and CEERS‑1025 (z=8.72; narrow-line)—while CIV and He II are absent, yielding extreme NV/CIV and NV/He II. The inferred incidence of narrow high-ionization UV lines is 12.5(+23.7/−10.4)% in LRDs and 2.2(+1.7/−1.0)% in UV-selected galaxies at z>4, implying hard radiation fields in a small subset and that dense H I may not fully cover some LRD nuclei. The line ratios and non-detections argue for extending searches down to the NV doublet, though statistics remain limited by the number of deep rest-UV spectra.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 2 (CEERS‑1025 G140H/G395M): Inspect the resolved NV doublet at the systemic redshift and verify the strong upper limits on CIV and He II; note the tentative [O III] detection anchoring zsys and the narrow-line widths.
Figure 3 (NV/CIV vs NV/He II): See where CEERS‑1025 and CEERS‑7902 land relative to low‑z AGN loci—both occupy the high‑NV quadrant, supporting nitrogen enhancement and/or resonant scattering rather than typical CIV/He II‑bright AGN.
Figure 4 ([O III]/[O II] vs [O III] EW): Compare the two NV emitters to CIV emitters and the [Ne V] source GN‑42437 to gauge ionization parameter and hardness; note whether the NV emitters align with extreme [O III] EW trends.
Figure 1 (SEDs/prism context): Use the BEAGLE fit for CEERS‑1025 and the prism spectra for LRDs CEERS‑7902 and CEERS‑10444 to understand continuum shapes, photometric constraints, and LRD SED context for the UV line analysis.

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2505.03183v1

The Physical Nature of the Off-centered Extended Emission Associated with the Little Red Dots

Chang-Hao Chen, Luis C. Ho, Ruancun Li, Kohei Inayoshi

Theme match 4/5

Digest

This Letter decomposes NIRCam imaging in 8 broad and 9 medium bands to isolate off-centered emission around four LRDs in Abell 2744 (UNCOVER + MegaScience). Three blobs are confirmed to be physically associated with their LRDs, with two showing medium-band excess consistent with very strong [O III] λλ4959,5007. While all three SEDs can be fit as ~10^8 Msun star-forming systems, the two [O III]-extreme cases are best explained as pure nebular emission from low-density, low-metallicity gas photoionized by the nearby LRD. Adopting LRD halo masses, the implied baryonic halo accretion rates are ~2–9 Msun/yr, suggesting growth to ~10^9 Msun by z≈4 if sustained at 10% star-formation efficiency.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 1 (multi-band decomposition for MSA10686): Inspect the data–model–residual panels across filters to verify that the PSF+Sérsic fit robustly separates the off-centered component, and note in which bands the blob emerges most clearly after nucleus subtraction.
Figure 2 (overlap probability vs redshift): Use this to gauge how likely a chance superposition is across z; the low overlap probability at the LRD redshifts supports physical association for three blobs.
Figure 3 (SED fits from GalfitS): Compare the EAzY photo-z model to the forced LRD-redshift model; identify the two blobs with medium-band spikes pinpointing [O III] λλ4959,5007, read off best-fit M*, and use the inset SFH to judge whether a stellar continuum is required versus nebular-dominated flux.
Figure 4 (scaling relations): See where the blobs fall relative to the z≳6 main sequence and mass–size relation compared to EELGs; note if the [O III]-extreme blobs deviate toward nebular-dominated loci while any stellar-continuum cases align more closely with EELGs.

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2505.06198v1

The "Dark-Matter Dominated" Galaxy Segue 1 Modeled with a Black Hole and no Dark Halo

Nathaniel Lujan, Karl Gebhardt, Richard Anantua, Owen Chase, Maya H. Debski, Claire Finley, Loraine V. Gomez, Om Gupta, Alex J. Lawson, Izabella Marron, Zorayda Martinez, Connor A. Painter, Yonatan Sklansky, Hayley West

Theme match 3/5

Digest

Orbit-based dynamical models of Segue 1 favor a central intermediate-mass black hole of 4 ± 1.5 × 10^5 M⊙, reproducing the stellar kinematics with a near-isotropic orbital structure. Zero–black-hole models both fit worse and require an extremely compact dark halo (scale radius ~100 pc) plus highly radial stellar orbits, while the BH model is also supported by a central rotation spike of 9.0 ± 2.4 km s−1. The tracer profile is built from number counts with tidal-stream subtraction and deprojection, and the stellar mass-to-light ratio remains poorly constrained, underscoring non-stellar mass dominance. Taken together, Segue 1 looks like a tidally stripped nuclear remnant and a nearby analog of Little Red Dots with overmassive black holes.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 1: Inspect the number-count profile before/after tidal subtraction to see how the tracer density used for modeling is constructed and extrapolated inward from ~1′–9′ via a smoothing spline.
Figure 2: Examine the rotation amplitude versus radius; the pronounced central rise (>99% significance) and lack of rotation beyond ~2′ bolster the case for a central massive object.
Figure 3: Read the χ² trends against stellar M/L, BH mass, dark-halo circular velocity, and scale radius; note the preferred BH mass (~4×10^5 M⊙) and that no-BH fits push toward very small halo scale radii (~100 pc).
Figure 4: Compare internal dispersion ratios for BH-included versus halo-only models; BH models remain near isotropic while halo-only demands strong radial anisotropy, highlighting the dynamical plausibility of the BH solution.

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2505.05942v1

Green Flash: Residual Emissions Enshrouded in Low-mass Balmer-break Galaxies at $z\sim5$

Kosuke Takahashi, Takahiro Morishita, Tadayuki Kodama, Zhaoran Liu, Kazuki Daikuhara, Nuo Chen

Theme match 3/5

Digest

JWST/NIRCam+NIRSpec data are used to isolate four low-mass Balmer-break galaxies in Abell 2744 at z=5.10–5.78 and fit their SEDs, showing they have been largely quiescent for ~100 Myr despite residual strong lines. All four require higher nebular than continuum attenuation, pointing to dusty star-forming pockets or obscured AGN as a lingering signature of quenching. For one galaxy with medium-band leverage, an Hβ+[O III] map shows centrally concentrated emission (Re≈0.7 kpc) that is more compact than the stellar body (Re≈0.9 kpc), favoring an outside-in quenching picture. Notably, one object (ID52153) sits on the z~5 main sequence even with a Balmer break, underscoring obscuration/bursty residual activity.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 1 (color–color selection): Verify that the four spectroscopic BBGs occupy the Balmer-break locus and are separated from emission-line–mimic tracks; use the CIGALE evolutionary curves to gauge post-quenching ages and SF timescales.
Figure 2 (RGB cutouts): Inspect central light concentration and morphology after PSF matching; compare blue (F115W) versus red (F356W/F444W) structure for hints of compact, older stellar cores versus enshrouded central activity.
Figure 3 (NIRSpec PRISM spectra): Check placement of the Balmer break and the continuum-subtracted Hβ+[O III] and Hα residuals; assess line strengths versus the quiescent-looking continuum consistent with enhanced nebular extinction.
Figure 4 (SFR–M⋆ at z~5): See which sources fall below the main sequence and the outlier ID52153 on it despite a Balmer break, highlighting obscured or bursty residual star formation.

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2505.02908v1

Early Shock-Cooling Observations and Progenitor Constraints of Type IIb SN 2024uwq

Bhagya M. Subrayan, David J. Sand, K. Azalee Bostroem, Saurabh W. Jha, Aravind P. Ravi, Michaela Schwab, Jennifer E. Andrews, Griffin Hosseinzadeh, Stefano Valenti, Yize Dong, Jeniveve Pearson, Manisha Shrestha, Lindsey A. Kwok, Emily Hoang, Jeonghee Rho, Seong Hyun Park, Sung-Chul Yoon, T. R. Geball, Joshua Haislip, Daryl Janzen, Vladimir Kouprianov, Darshana Mehta, Nicolás Meza Retamal, Daniel E. Reichart, Moira Andrews, Joseph Farah, Megan Newsome, D. Andrew Howell, Curtis McCully

Theme match 2/5

Digest

Early multiwavelength follow-up of the Type IIb SN 2024uwq captures the shock-cooling bump and the subsequent second peak, with early spectra showing broad H-alpha (~15,500 km s^-1) and He I P-Cygni features of comparable strength that evolve toward stronger He and fading H. Modeling of the shock-cooling phase and a bolometric light-curve fit (two-component Arnett) favor a partially stripped progenitor with radius 10–60 R_sun and a residual hydrogen envelope of 0.7–1.35 M_sun. The inferred ZAMS mass of 12–20 M_sun and likely binary stripping place SN 2024uwq between compact and extended IIb events. The work underscores the value of very-early UV/optical coverage for mapping the continuum of stripped-envelope progenitors.

Open paper page arXiv abstract arXiv PDF Highlighted PDF

Key figures to inspect

Figure 2: Inspect the early-time multi-band light curves to locate the shock-cooling peak relative to t0=MJD 60558.63 and gauge its color/UV strength; the grey vertical lines mark spectra epochs to connect photometric phases with spectral evolution.
Figure 3: Compare the absolute B-band light curve and UB/BV/gr/ri color evolution against IIb benchmarks (1993J, 2008ax, 2011dh, 2011fu, 2013df, 2016gkg) to see why 2024uwq sits between compact and extended IIb (width and spacing of the two peaks, color tracks).
Figure 4 (left): Use the bolometric luminosity with temperature and photospheric-radius evolution to identify the epochs used for shock-cooling modeling (T_BB > 8120 K) and to see the growth/decline of R_ph through the first and second peaks.
Figure 4 (right): Examine the two-component Arnett MCMC fit to see how inner vs outer ejecta components reproduce the second peak and tail, informing Ni heating vs extended-envelope contributions.
Figure 1: Check field/host context in NGC 6902 and precise SN location for follow-up aperture choices and potential host-background systematics.