Formation and Growth of Supermassive Black Holes

Supermassive black holes (SMBHs), with masses ranging from millions to billions of solar masses, lie at the centres of most massive galaxies and power luminous quasars. Their origin and rapid assembly in the first billion years after the Big Bang remain key questions in astrophysics. Two principal seeding channels have been proposed: light seeds, born from the remnants of the first generation of massive stars, and heavy seeds, produced via direct collapse of dense gas in primordial haloes. Subsequent growth occurs through gas accretion—regulated by radiation pressure, feedback and the Eddington limit—and hierarchical mergers of host galaxies. In dense, metal-poor environments, angular momentum transport can drive efficient inflows that feed black hole growth, while powerful jets and winds can self‐regulate accretion. Observational breakthroughs with facilities such as JWST, Chandra and ground‐based radio arrays have revealed quasars at redshifts z > 7, signalling that billion-solar-mass SMBHs were already in place within 700 million years. Cosmological simulations and semianalytic models now trace the interplay between baryonic physics and black hole dynamics, linking early seeding conditions to host galaxy evolution. This research has broad implications for cosmic reionisation, galaxy formation and the expected gravitational‐wave background from black hole mergers.

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Formation and Growth of Supermassive Black Holes publication trend

The graph below shows the total number of articles in formation and growth of supermassive black holes across all publications each year (not limited to Nature Index journals).

Technical terms

Seed black hole: A nascent black hole formed in the early universe, either from stellar remnants or direct gas collapse, that provides the initial mass for subsequent growth.

Eddington limit: The balance point at which outward radiation pressure from accretion equals the inward gravitational pull, setting a natural luminous ceiling for steady accretion.

Super-Eddington accretion: A regime in which the mass inflow rate temporarily exceeds the Eddington limit, often accompanied by inefficient radiation trapping and powerful outflows.

Direct collapse: A formation pathway in which dense gas clouds collapse under gravity directly into a massive black hole without fragmenting into stars.

Quasar: An extraordinarily luminous active galactic nucleus powered by rapid accretion onto a supermassive black hole.

References

1. First Detection of an Overmassive Black Hole Galaxy UHZ1: Evidence for Heavy Black Hole Seed Formation from Direct Collapse. The Astrophysical Journal Letters (2023).
2. How the super-Eddington regime regulates black hole growth in high-redshift galaxies. Astronomy & Astrophysics (2023).
3. Direct Formation of Massive Black Holes via Dynamical Collapse in Metal-enriched Merging Galaxies at z ∼ 10: Fully Cosmological Simulations. The Astrophysical Journal (2024).