MEOW: JWST/MIRI Unveils a Hidden Population of Ancient Black Holes ✛
Context
Modern astrophysics faces a paradox: James Webb and other telescopes spot hundreds of quasars hosting black holes of a billion solar masses just 700 million years after the Big Bang. To grow so fast, these monsters must have gobbled up matter at breakneck speed, yet observations show their active phase is brief—only a few million years. This tension can be resolved if much of the growth is hidden from us by dust clouds. That's exactly the "shadow" population the MEOW survey sought, tapping MIRI's unique sensitivity on JWST to the thermal glow of dust. According to Edwin Hubble's law, distant galaxies race away from us, stretching light into the red, and a key sign of activity are broad hydrogen emission lines like Hα, discovered by Johann Balmer.
Methods
The researchers used 43 MIRI pointings for the MEOW survey, covering 95 square arcminutes in the GOODS-N and GOODS-S fields. The F1000W and F2100W filters (at 10 and 21 microns) capture the thermal glow of carbon-based dust heated to about 1200 K by a black hole's accretion disk. Cross-matching with archival Hubble and NIRCam data enabled the construction of spectral energy distributions (SEDs) for thousands of galaxies. Then modeling with the CIGALE code teased out the AGN contribution. By combining deep spectroscopy from NIRCam and NIRSpec, the team confirmed redshifts for most objects, including Hα and [OIII] lines.
Results
In the final sample of 16 AGN, 12 turned out to be new, missed by previous surveys. Five of the seven objects with available Hα line spectra showed no broad emission lines, meaning they are narrow-line type II AGN—classic "obscured" sources. The other two did show broad lines, but with different infrared emissions: one matches a "little red dot" (LRD), the other a typical quasar with a powerful hot dust component. Bolometric luminosities range from $10^{44.6}$ to $10^{46.4}$ erg/s. The luminosity function at z=4.5–6 shows that the space density of such hidden AGN is comparable to that of broad-line quasars and LRDs, and at high luminosities even surpasses it.
Implications
These results mean that the census of active nuclei in the young Universe was far from complete. A significant fraction of supermassive black hole growth occurred under "dark accretion," hidden from optical telescopes. This calls for a revision of models for the co-evolution of galaxies and their central monsters. Moreover, the variety of conditions in host galaxies—from dense circumnuclear tori to galaxy-wide obscuration—points to multiple obscuration mechanisms, complicating a unified picture.
Future development
In the future, as MIRI data accumulate over larger areas, we can push into fainter luminosities and higher redshifts. This will reveal whether torus or galactic-scale dust dominates at different epochs. Combining with X-ray surveys (e.g., the future Athena telescope) and more sensitive spectroscopy will provide a complete picture of accretion across cosmic history.
Impact
The discovery will impact early-universe cosmology, the theory of galaxy formation, and accretion physics. It also underscores the importance of infrared surveys for future missions like LUVOIR or HabEx.
Next steps
Deeper spectroscopic studies with NIRSpec will help refine black hole masses and dust properties. Expanding MIRI coverage to other deep fields is also needed to rule out chance fluctuations.
Key open problems
The work ties directly to the puzzle of supermassive black hole origins: how they managed to grow to billions of solar masses so quickly after the Big Bang. Hidden accretion likely partially solves this riddle, but questions about initial seeds and the efficiency of super-Eddington growth remain.
The knowledge machine's view
This section is addressed to the author of the paper and their colleagues. Neighbouring works were found by meaning-based search across our archive, not by word overlap. We do not review: we show the field around the work.
What the work does
The authors used the MEOW survey with JWST/MIRI to find dusty active galactic nuclei (AGN) at z = 4.5–6, selecting 16 objects by their infrared excess and confirming 12 of them as new. They showed that the space density of such obscured AGN is comparable to that of broad-line quasars and LRD, and at high luminosities even exceeds it.
Where its strength is
The strength of the work lies in the direct detection of a population of obscured AGN based on deep MIRI data, which allows a quantitative estimate of the contribution of hidden accretion to the growth of supermassive black holes in the early Universe.
Where it could go next
- It might be interesting to compare the obtained luminosity function of obscured AGN with predictions from black hole growth models, for example, with the work on the contribution of small black holes to the formation of giants.based on: Tiny Black Holes Build Giants arXiv:2607.09201
- A related study is the investigation of a single dusty black hole in a young galaxy; comparing its properties with your sample could clarify the diversity of obscured AGN.based on: Dusty Black Hole in a Young Galaxy arXiv:2507.20684
- A possible follow-up is to study how such obscured AGN affect the surrounding gas and star formation, building on the work on the suppression of star formation by an active nucleus.based on: The 'Chef' Black Hole That Prevents Star Birth arXiv:2512.14066
Worth trying
- Test how the fraction of obscured AGN changes from moderate luminosities to quasar-like ones, using wider MIRI surveys.
- Cross-match the sample with LRD catalogs and check for overlap in colors and morphology.
- Estimate the contribution of obscured AGN to the cosmic X-ray background by extrapolating the luminosity function to higher redshifts.
Why this may matter
Accounting for hidden accretion could significantly change estimates of the growth rate of supermassive black holes in the early Universe and help explain how they managed to gain mass in a short time.
Nearby works in our archive
- Tiny Black Holes Build Giantssimilarity 0.64
- The 'Chef' Black Hole That Prevents Star Birthsimilarity 0.62
- Dusty Black Hole in a Young Galaxysimilarity 0.61
- The Hidden Light of Young Galaxiessimilarity 0.61
- Two massive black holes swept clean the center of a galaxysimilarity 0.61
- Invisible Conductors of Galactic Diskssimilarity 0.61
The closest work in the archive sits at 0.64 by meaning — the usual level for our corpus.
Original abstract
as written by the authors arXiv:2607.02666v1
We present the MIRI Early Obscured-AGN Wide Survey (MEOW), a JWST/MIRI imaging survey designed to detect dust-obscured active galactic nuclei (AGN) across cosmic time, with a particular focus on the high-redshift universe at $$z \gtrsim 5$$. MEOW observes the GOODS-N and GOODS-S fields with 43 pointings covering 95 arcmin$$^2$$ with the F1000W and F2100W filters, reaching depths of 0.5 and 3.6 $$\mu$$Jy ($$5\sigma$$), respectively. Using spectral energy distribution (SED) modeling combining MEOW photometry with archival HST, JWST/NIRCam, and SCUBA-2 data, we identify a sample of 16 MIRI-selected AGN at $$z = 4.5$$--$$7.2$$ (12 spectroscopically confirmed), spanning bolometric luminosities of $$L_{\rm bol} = 10^{44.6}$$--$$10^{46.4}$$~erg~s$$^{-1}$$. Twelve of the 16 AGN are newly identified in this work, including at least five narrow-line AGN representing the obscured population to which broad-line spectroscopic searches are insensitive. Two broad-line AGN exhibit markedly different mid-infrared emission properties, consistent with one being a little red dot (LRD) and the other either a typical AGN or an LRD with unusually strong hot-dust emission. The MIRI-selected AGN bolometric luminosity function at $$z = 4.5$$--$$6$$ yields number densities comparable to those of broad-line AGN and LRDs, suggesting that obscured AGN contribute significantly to the total AGN census at these epochs. The narrow-line AGN reside in diverse host environments, with evidence for both circumnuclear and host-galaxy-scale obscuration, pointing to multiple physical mechanisms at work. These results establish JWST/MIRI imaging as an indispensable component of a multi-faceted approach to a complete census of early supermassive black hole growth.
The survey's name MEOW is an acronym that plays on a cat's meow, which the authors say evokes curiosity and night hunting, as the survey "hunts" for hidden objects in the infrared.
Key numbers
- Surveyed area: 95 arcmin^2
- F2100W sensitivity: 3.6 µJy (5σ)
- Number of detected AGN: 16
- Of which new: 12
- Redshift range: 4.5–7.2