Active Galactic Nuclei and Star Formation Dynamics

Active galactic nuclei (AGNs) represent the energetic centres of galaxies in which accretion onto a supermassive black hole releases vast amounts of radiation and mechanical energy. The interplay between this central engine and surrounding interstellar gas regulates the growth of both the black hole and its host galaxy. Inflows of cold gas can fuel concurrent episodes of star formation and black-hole accretion, while powerful outflows and jets driven by the AGN can heat or expel gas, quenching further star formation. Observations across the electromagnetic spectrum—from radio interferometry and millimetre spectroscopy to optical and infrared integral-field mapping—are revealing a complex web of co-evolutionary processes. Studies of galaxies at cosmic noon (z ≃ 1–3) indicate that AGN feedback can both trigger star formation in compressed shells and suppress it over larger scales. The balance between gas inflow, starburst activity and AGN-driven feedback determines the ultimate stellar mass and morphology of massive galaxies, with key implications for the assembly of the cosmic web and the chemical enrichment of the intergalactic medium.

Research from Nature Portfolio

Recent studies have uncovered a dense swarm of companion galaxies around a hyper-luminous, hot dust-obscured system at z ≃ 3.6, all detected via extended Lyman-α emission over scales of several hundred kiloparsecs. Despite the crowded environment, there is no clear evidence for ongoing major mergers; instead, the central galaxy appears to sustain its intense star formation and black-hole growth through a fast-rotating molecular disc. This finding challenges the notion that only dramatic interactions drive the most extreme phases of AGN activity and suggests that smooth accretion of smaller satellites or filamentary inflows may dominate in some of the Universe’s most luminous systems.

Active Galactic Nuclei and Star Formation Dynamics publication trend

The graph below shows the total number of articles in active galactic nuclei and star formation dynamics across all publications each year (not limited to Nature Index journals).

Technical terms

Active Galactic Nucleus (AGN): A compact region at the centre of a galaxy where a supermassive black hole accretes matter, emitting high luminosities across the electromagnetic spectrum.

Eddington Ratio: The ratio of an object’s luminosity to its Eddington luminosity, indicating how close an accreting black hole is to the theoretical maximum steady brightness.

Ionization Cone: A biconical region of ionised gas emanating from an AGN, illuminated by anisotropic radiation escaping along the axes of an obscuring torus.

Circumnuclear Disk: A rotating disc of gas and dust located within a few hundred parsecs of a galaxy’s nucleus, often supplying fuel for both star formation and AGN activity.

Shock-Excited Region: A zone where gas is heated and ionised by the passage of a supersonic shock, typically driven by AGN outflows or galaxy interactions.

References

1. Detection of companion galaxies around hot dust-obscured hyper-luminous galaxy W0410-0913. Nature Communications (2022).
2. First Results from the JWST Early Release Science Program Q3D: Ionization Cone, Clumpy Star Formation, and Shocks in a z = 3 Extremely Red Quasar Host. The Astrophysical Journal (2023).
3. Similarity between Compact Extremely Red Objects Discovered with JWST in Cosmic Dawn and Blue-excess Dust-obscured Galaxies Known in Cosmic Noon. The Astrophysical Journal Letters (2023).
4. Gravitational Instability of Gas–Dust Circumnuclear Disks in Galaxies. Galaxies (2023).