Where the red rise stops: JWST/MIRI reveals a near-infrared turnover in the Little Red Dot Abell2744-QSO1

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Little Red Dots (LRDs) are compact sources with a blue rest-frame UV, a steep red optical continuum and, often, broad hydrogen lines. They have been interpreted as dense stellar systems, dust-reddened active galactic nuclei, or black holes embedded in dense, dust-poor gas, scenarios that are hard to tell apart in the rest-frame UV and optical. We present JWST/MIRI F770W and F1000W imaging of the triply lensed Abell2744-QSO1 at z=7.04, probing rest-frame 0.96 and 1.24um. QSO1 is unresolved, and its steep optical rise stops near rest-frame 1um. Up to 1.24um, a T~4450K blackbody, or a hotter one reddened by dust, describes the continuum, with no sign of the hot dust seen in most type-1 quasars. Our statistically preferred SED fits produce the red continuum with (3-4)x10^9 Msun of stars, over 100 times the dynamical limit on the host mass, and are therefore disfavoured. An accretion disc in a dense gas cocoon respects this limit but over-predicts the 1.24um flux by 5 sigma. Super-Eddington accretion models with a thermalising envelope reproduce the turnover, but only for a black hole ~2.5dex less massive than the dynamical estimate. For a dust-reddened accretion disc (A_V ~ 2 mag), dust at ~1200K can re-emit at most ~2 per cent of the absorbed luminosity, and most of it would have to emerge at ~70-600K, unless the dust covers only a small fraction of the sky. The dynamics favour an accretion-powered source, but our data cannot distinguish dust reddening from processing by dense gas. MIRI imaging at >18um could separate these scenarios.

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The origin of the rest-optical continuum emission is perhaps most contentious. If dominated by the emission from a (strongly) dust-attenuated AGN, the implied host galaxy mass is small, resulting in a black hole to host mass ratio that lies far above well-established scaling relations in the local Universe ( Maiolino et al., 2024 ; Pacucci et al., 2023 ; Furtak et al., 2024 , e.g.) , although this may in part be driven by uncertainties in the black hole and galaxy masses as well as selection effects ( Li et al., 2024 ; Lupi et al., 2024 ; Wang et al., 2024b , e.g.) . If confirmed, such a large population of overmassive black holes may have important implications for the seed masses and growth mechanisms of early black holes ( Kokorev et al., 2023 ; Bogdán et al., 2024 ; Goulding et al., 2023 , e.g.) , and would be in tension with current cosmological hydrodynamical simulations ( Habouzit, 2025 ; Matthee et al., 2024b , e.g.) . Intriguingly, however, the transition in the v-shaped SED from blue to red has been shown to occur at the Balmer limit for ∼ 50 % \sim 50\% of LRDs ( Setton et al., 2024 ) , and some LRDs show Balmer breaks that are as strong as those observed in high-redshift post-starburst galaxies ( Labbe et al., 2024 ; Wang et al., 2024b ; Ma et al., 2024 , e.g.) . At face value, it therefore appears reasonable to interpret the rest-optical as being dominated by emission from an evolved stellar population in a host galaxy instead of by an AGN.

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The SED is characterised by a Balmer break that exceeds the break strengths of z > 3 z>3 massive quiescent galaxies and LRDs published thus far by a factor 2. Together with a (weak) blue UV slope, this gives rise to the ‘v-shape’ typically observed in LRDs. The PRISM spectrum (extending to rest 1.2 ​ μ ​ m 1.2\,\rm\mu m ) and MIRI photometry (rest ∼ 2 − 4 ​ μ ​ m \sim 2-4\,\rm\mu m ) reveal a blue SED in the near- and mid-IR, indicating there is no evidence of hot dust emission at least to rest ≲ 4 ​ μ ​ m \lesssim 4\,\rm\mu m .

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Table Extended Data 1: Summary of key properties.

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We thank the PRIMER and EXCELS teams for designing JWST surveys that made this work possible. We acknowledge feedback on ”BH*” and illuminating discussions with Ivan Cabrera-Ziri, Mike McDonald, Roger Blandford, Susan Clark, Risa Wechsler, Tom Abel, Mike Liu, Dave Sanders, Sylvain Veilleux, Triana Almeyda, Adam Ginsburg, and Desika Narayanan. We thank Kohei Inayoshi for discussing details of their work modeling Balmer breaks in LRDs [ 8 ] . This work is based on observations made with the NASA/ESA/CSA James Webb Space Telescope. The data were obtained from the Mikulski Archive for Space Telescopes at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-03127 for JWST. These observations are associated with programs 5224 and 3543. Some of the data products presented herein were retrieved from the Dawn JWST Archive (DJA). DJA is an initiative of the Cosmic Dawn Center (DAWN), which is funded by the Danish National Research Foundation under grant DNRF140. We acknowledge funding from JWST programs GO-3516, GO-5224, and GO-1837. Support for this work was provided by NASA through the NASA Hubble Fellowship grant HST-HF2-51515.001-A awarded by the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555. Funded by the European Union (ERC AGENTS, 101076224; HEAVYMETAL, 101071865; RED CARDINAL, 101076080). Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the European Research Council. Neither the European Union nor the granting authority can be held responsible for them. This work has received funding from the Swiss State Secretariat for Education, Research and Innovation (SERI) under contract number MB22.00072, as well as from the Swiss National Science Foundation (SNSF) through project grant 200020_207349. This work was also supported by JSPS KAKENHI Grant Numbers 23H00131. The Cosmic Dawn Center is funded by the Danish National Research Foundation under grant DNRF140. P.N. acknowledges supp

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The XRD presents a unique set of properties that challenge standard classification. Although its high X-ray luminosity ( L 2 − 10 ​ keV ≳ 10 44 L_{\rm 2-10\,keV}\gtrsim 10^{44} erg s -1 ) and spectral shape ( Γ ∼ 1.8 \Gamma\sim 1.8 ) would normally unambiguously identify it as a typical AGN, it shares striking similarities with the LRD population. Specifically, it exhibits a V-shaped spectral continuum with blackbody-like emission, non-Gaussian broad lines with significant wings, and weak mid-IR emission in conflict with the existence of a hot-dust torus. However, a key distinction in the UV-optical SED remains: the spectral inflection point lies blueward of the Balmer limit, rather than at or redward of the Balmer limit as is typical of LRDs [ 29 ] .

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We have systematically explored whether the properties of the XRD can be explained by dust obscuration. However, standard dust models fail to reproduce the observed SED without invoking a combination of an extremely steep attenuation curves at high dust extinction that are inconsistent with those observed in local galaxies or AGN. Dust-obscured AGN models also require hot dust components that are incompatible with the observed Spitzer photometry based on typical AGN scaling relations. Although hot-dust–deficient quasars have been observed in X-ray AGN surveys [ 46 ] , they are typically UV-luminous. The fact that the narrow-line Balmer decrement is consistent with case B recombination implies that the obscuration is primarily nuclear. This would necessitate a nuclear dust component, which typically produces strong hot dust emission, and is therefore in tension with the absence of IR emission in a hot-dust–deficient quasar interpretation. Although we cannot strictly rule out exotic dust scenarios for this single source without further data, for these reasons we do not prefer attributing the XRD’s properties to a dust-obscured AGN.

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The maximum-likelihood model is shown in Fig. 1 . The H α narrow line is clearly detected, with the observed flux F n ​ ( H α ) F_{\mathrm{n}}(\text{H\,\textalpha}) being more than 8 σaway from 0 (Table 1 ). Together with weaker H β and [O iii ]λ5007 , the observed wavelength of narrow H α implies a redshift z = 7.0367 ± 0.0001 z=7.0367\pm 0.0001 . The intrinsic width of the narrow lines is extremely small, σ n = 22 − 6 + 5 \sigma_{\mathrm{n}}=22_{-6}^{+5} \kms , corresponding to 0.6 times the spectral resolution ( F ​ W ​ H ​ M = 81 ​ \kms FWHM=81~\kms , σ R = 34 ​ \kms \sigma_{R}=34~\kms at the observed wavelength of H α ). While the inferred σ n \sigma_{\mathrm{n}} is small, a simple analytical calculation tells us that, given a Gaussian LSF with R = 3,700 R=3,700 and a line detection with SNR of 8, we can detect a spectral broadening of σ = 22 \sigma=22 \kms at 4.8 σ ( Zhou et al., 2017 ) ; this statistical significance is slightly better yet comparable to the width of the posterior probability on σ n \sigma_{\mathrm{n}} (i.e., 22 / 6 = 3 22/6=3 -σsignificance). The larger uncertainties for our measured σ n \sigma_{\mathrm{n}} relative to the analytical prediction can easily be explained by the presence of additional unknowns compared to the analytic approximation of Zhou et al. (2017) , such as the absorber depth and redshift. We find no evidence of [N ii ]λλ6548,6583 , with F n ​ ( [N ii ]λ6583 ) / F n ​ ( H α ) < 0.16 F_{\mathrm{n}}(\text{[{N}\,{\sc{ii}}]{\textlambda}{6583}{}{}})/F_{\mathrm{n}}(\text{H\,\textalpha})<0.16 (3 σ).

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Table 1 : Summary of the emission-lines model of Abell2744-QSO1, reporting the median and 16 th –84 th percentile range of the posterior probability distribution on 17 parameters of the model (Section 2 ; four free parameters for the continuum are not listed). The ‘n’ and ‘b’ subscripts denote values inherent to the narrow lines and to the (two-component) broad lines, respectively.

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Higher-resolution spectroscopy yields an increased recovery fraction for absorption features in LRDs, up to 40 − 60 % 40-60\% at R ∼ 2700 R\sim 2700 from 10 − 20 % 10-20\% at R ∼ 1000 R\sim 1000 . This recovery is partly dependent on optical continuum flux for medium-resolution surveys. However, high-resolution surveys like OCEANS may probe the fraction of absorbers more efficiently as demonstrated through our recovery of absorption features lost in sources observed at lower spectral resolution. Absorption in LRDs tends to be near-zero in absorption velocity with a median velocity offset of − 49 -49 kms − 1 \rm{km}\rm{s}^{-1} and median absorption EW of 5.3 Å.

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The OCEANS high-resolution spectroscopy program provides a new look at LRDs with Balmer absorption. The OCEANS sample was compiled from an amalgamation of targets in CEERS, and so we select LRDs that (1) satisfy the photometric criteria in Barro et al. [6] , (2) are compact in rest-optical light, and (3) have broad H α \alpha and/or H β \beta . We identify 10 LRDs from the OCEANS data, 4 of which have Balmer-line absorption.

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Table 2 summarizes the median posterior values for our sample. To further compare our inferences with previous work, we directly compare the bolometric luminosity estimate for individual LRDs. We adopt the bolometric luminosities from Akins et al. [2] (i.e., log ⁡ L bol , QSO \log L_{\rm bol,~QSO} ), which they derived with their dusty QSO spectral model. For our BHE model, we compute the bolometric luminosity, log ⁡ L bol , BHE \log L_{\rm bol,~BHE} , by integrating the intrinsic (unattenuated) blackbody spectrum. We do not include the UV power-law component into our bolometric luminosity measurement. As shown in the Figure 2 , the bolometric luminosities based on BHE and dusty QSO models differ significantly. L bol , BHE L_{\rm bol,~BHE} typically amounts to only ∼ 2 % \sim 2\% of L bol , QSO L_{\rm bol,~QSO} . Akins et al. [2] adopt a dusty QSO SED with A V ∼ 3 A_{V}\sim 3 for LRDs, so that the strongly attenuated UV emission is reprocessed into the near-infrared, thereby elevating the inferred bolometric output. In contrast, our BHE model reproduces the optical SED with more modest dust attenuation, A V ∼ 1 A_{V}\sim 1 , because the blackbody continuum naturally explains the observed optical bump. The resulting bolometric correction from the rest-frame 5100 Å luminosity is ≃ 4.4 \simeq 4.4 in the BHE model, slightly smaller than the canonical value of ∼ 10 \sim 10 commonly adopted for local blue quasars [ 54 ] . The combination of the reduced dust attenuation at optical wavelengths (flux suppression factor ∼ 10 − 0.4 ​ ( 3 − 1 ) ≃ 0.16 \sim 10^{-0.4(3-1)}\simeq 0.16 ) and the smaller bolometric correction for the dust-attenuation–corrected spectrum (factor ∼ [ 4.4 × 10 − 0.4 ] / 10 ≃ 0.18 \sim[4.4\times 10^{-0.4}]/10\simeq 0.18 ) jointly accounts for the low normalization, yielding L bol , BHE ≃ 0.02 ​ L bol , QSO L_{\rm bol,~BHE}\simeq 0.02\,L_{\rm bol,~QSO} . Because the BHE framework replaces the dusty-QSO interpretation in earlier work and yields substantially lower bolometric luminosities for LRDs, population-level quantities such as the luminosity function and the black hole accretion density should be revised accordingly.

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In this Letter, we reanalyzed the COSMOS-Web LRD sample using the black-hole-envelope (BHE) model, which describes super-Eddington accretion surrounded by an optically thick envelope. The BHE model reproduces the characteristic optical V-shaped continuum through photospheric emission at T ph ∼ 4000 − 6000 T_{\rm ph}\sim 4000-6000 K and naturally explains the lack of far-infrared detections without invoking heavy dust obscuration. The inferred bolometric luminosities are typically 1-2 dex lower than those derived from quasar templates, bringing the number densities of LRDs into agreement with the faint-end extrapolation of known AGN luminosity functions. The resulting black hole mass function and accretion-rate density smoothly connect to those of ordinary AGNs at z ≲ 5 z\lesssim 5 , suggesting that LRDs represent a short-lived, efficient growth phase in the early build-up of supermassive black holes. Expanded MIRI coverage from programs such as COSMOS-3D [ 32 , GO-5893; PI. Koki Kakiichi; ] will improve constraints on the rest-frame optical–to–NIR spectral properties of LRDs. Future spectroscopy (e.g. EMBER program; GO-7076; PI: Hollis Akins) and variability monitoring will be crucial to confirm the physical nature and duty cycle of this LRD-phase.

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We now consider the results in the context of the broader sample. Within the high signal-to-noise sample at 2 < z < 3 2<z<3 , two out of four objects show clear water absorption, while the others have similar overall SEDs but appear modestly bluer (see Methods). Compared to the broader LRD population spanning z ∼ 2 − 7 z\sim 2-7 (Fig. 3 ), the two objects studied here have consistent bolometric luminosities, but lie toward the redder end of the color distribution and colder end of the inferred temperature distribution. If the thermal interpretation of the rest-frame optical spectra of LRDs is correct, the reddest LRDs should also be the coolest Barro et al. (2025) ; de Graaff et al. (2025) ; Umeda et al. (2025) , in tentative agreement with our findings.

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The exact threshold value of − 0.2 -0.2 for r H 2 ​ O r_{\rm H_{2}O} is chosen to minimize contamination from sources whose apparent signal arises from a sloping continuum rather than from a genuine absorption feature. The precise numerical value is not critical for the conclusions of this paper, especially given the limited sample size. Four out of the eight LRDs satisfy the S/N requirement. The generally low S / N \mathrm{S/N} across the broader sample arises primarily from increased noise near the detector edge of NIRSpec. Applying the r H 2 ​ O r_{\rm H_{2}O} selection yields two sources, namely WIDE-EGS-2974 and UNCOVER-A2744-20698. We visually inspect both spectra to confirm the presence of water absorption. The r H 2 ​ O r_{\rm H_{2}O} values for WIDE-EGS-2974 and UNCOVER-A2744-20698 are -0.32 and -0.20, respectively. In summary, water absorption is detected in two out of the four LRDs for which the spectral coverage and S/N allow such a feature to be measured.

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We report the values of sample variance, mean square error, excess variance, fractional variability (and 3 ​ σ 3\sigma upperlimit) of our target Pelias in Table 5 . The resulting 3 ​ σ 3\sigma upper limits on the intrinsic fractional variability range from F var , 3 ​ σ < 0.18 F_{\rm var,3\sigma}<0.18 (F115W) to F var , 3 ​ σ < 0.47 F_{\rm var,3\sigma}<0.47 (F277W), implying no evidence for significant variability at the ≤ 20 − 50 \leq 20-50 % level, depending on filter, thus ruling out any possible impact of transient phenomena at the origin of our target SED shape.

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s on the order of log 10 ⁡ ( M ∙ ​ [ M ⊙ ] ) = 5.8 − 6.8 \log_{10}(M_{\bullet}\penalty\ [\rm M_{\odot}])=5.8-6.8 (see § 3.5 ), assuming λ = 1 \lambda=1 and 0.1, respectively. When compared to the total stellar mass of the host galaxies, such SMBH masses result in constituting from 6% to 60% of it. Even allowing for substantial systematic uncertainties in the SED-based M ∙ M_{\bullet} estimates, such ratios lie well above the extrapolation of the local M ∙ M_{\bullet} - M ⋆ M_{\star} relation into the dwarf regime, see Figure 7 . This suggests that either the black holes in these systems are already over-massive relative to their hosts, or that we are catching the galaxies at an early phase in which the stellar component has not yet “caught up” with the rapid black hole growth. Interestingly, similarly extreme black-hole-to-stellar mass ratios have been proposed in other low- z z dwarf galaxies. The Local Group dwarf Leo I ( McConnachie, 2012 , M ⋆ ≈ 10 6.7 ​ M ⊙ M_{\star}\approx 10^{6.7}\penalty\ \rm M_{\odot} ) may host a black hole with mass comparable to that of its stellar component, implying M ∙ / M ⋆ ≈ 1 M_{\bullet}/M_{\star}\approx 1 , far above the local scaling relations and potentially reflecting the relic signature of an early heavy-seed black hole ( Bustamante-Rosell et al., 2021 ; Scoggins et al., 2025 , e.g.,) . Recently, also Young et al. (2026) reported the identification of two galaxies at z ≲ 1 z\lesssim 1 with candidate intermediate mass BHs that also lie above the local M ∙ − M ⋆ M_{\bullet}-M_{\star} relation, one of which at similar M ⋆ M_{\star} to our targets (ID 3976, z phot = 1.03 z_{\rm phot}=1.03 ).