Super-eddington accretion

Definition

Super-eddington accretion refers to the process where a massive object, such as a black hole or neutron star, accretes matter at a rate that exceeds the Eddington limit. The Eddington limit is the maximum luminosity a body can achieve when there is a balance between the outward radiation pressure and the inward gravitational force. When this limit is surpassed, it has significant implications for the formation and growth of supermassive black holes as well as the behavior and structure of accretion disks around these objects.

5 Must Know Facts For Your Next Test

1. Super-eddington accretion can lead to rapid growth of black holes, allowing them to gain mass quickly during certain phases of their evolution.
2. This process may occur in environments rich in gas, such as during galaxy mergers or in dense star clusters, where high-density conditions enable matter to be funneled toward the black hole.
3. When accretion exceeds the Eddington limit, strong outflows or jets can be produced as a mechanism to expel excess material and stabilize the system.
4. Super-eddington accretion is crucial for understanding how supermassive black holes formed in the early universe and how they reached their massive sizes so quickly.
5. Observational evidence of super-eddington accretion has been found in certain active galactic nuclei (AGN), showcasing high luminosities that suggest rapid mass growth.

Review Questions

• How does super-eddington accretion influence the growth of supermassive black holes in the early universe?
  • Super-eddington accretion is key to explaining the rapid growth of supermassive black holes shortly after the Big Bang. The conditions in the early universe, like dense gas clouds and mergers of galaxies, allowed massive black holes to accrete matter at rates that exceeded the Eddington limit. This rapid mass accumulation is vital for understanding how these black holes could reach billions of solar masses within just a few hundred million years after their formation.
• Discuss the implications of exceeding the Eddington limit during the accretion process, particularly in relation to energy outputs and outflows.
  • When super-eddington accretion occurs, the energy generated by infalling matter can lead to intense radiation pressure that may result in powerful outflows or jets. These outflows serve as a mechanism to expel excess material and prevent runaway growth of the black hole. The relationship between these energetic phenomena and their ability to regulate further accretion is crucial for understanding the dynamics of accretion disks and their feedback effects on galactic environments.
• Evaluate how the study of super-eddington accretion can enhance our understanding of galaxy formation and evolution.
  • Studying super-eddington accretion sheds light on critical processes involved in galaxy formation and evolution. It provides insights into how supermassive black holes influence their host galaxies through feedback mechanisms that regulate star formation and gas dynamics. By examining cases of super-eddington behavior in various cosmic environments, researchers can piece together a more complete picture of how galaxies evolve over cosmic time, revealing connections between black hole growth and large-scale structures in the universe.

Related terms

Eddington Limit: The maximum luminosity a celestial object can achieve, defined by the balance between gravitational forces and radiation pressure.

Accretion Disk: A structure formed by diffused material in orbital motion around a massive central body, where matter spirals inward and releases energy as it falls.

Black Hole: An astronomical object with an extremely strong gravitational pull, from which nothing can escape, not even light, typically formed from collapsing stars.