AGN feedback

Definition

AGN feedback refers to the processes by which the energy and momentum from an active galactic nucleus (AGN) influence the surrounding interstellar medium and galaxy. This interaction can regulate star formation, affect galaxy evolution, and play a crucial role in the growth of supermassive black holes. Understanding AGN feedback is key to comprehending how galaxies evolve over cosmic time and how they interact with their environment.

5 Must Know Facts For Your Next Test

1. AGN feedback can manifest as powerful outflows of gas and energy, which can heat or expel surrounding gas, inhibiting star formation.
2. There are two main types of AGN feedback: radiative feedback, which involves radiation pressure from the AGN, and mechanical feedback, which includes jets and winds generated by accreting material.
3. Models incorporating AGN feedback show that it is essential for explaining observed correlations between black hole mass and the properties of host galaxies.
4. The balance between AGN feedback and star formation can significantly shape the evolution of galaxies over time, influencing their morphology and stellar populations.
5. Observations of AGNs across various wavelengths (radio, optical, X-ray) have provided evidence for feedback mechanisms at work in different environments.

Review Questions

• How does AGN feedback influence star formation in galaxies?
  • AGN feedback influences star formation by exerting pressure on the surrounding interstellar medium through radiation and energetic outflows. These processes can heat or expel gas that would otherwise cool and condense into new stars. By regulating the amount of available cold gas, AGN feedback plays a crucial role in determining when and where star formation occurs within galaxies.
• Evaluate the different types of AGN feedback mechanisms and their impacts on galaxy evolution.
  • There are primarily two types of AGN feedback mechanisms: radiative feedback and mechanical feedback. Radiative feedback involves radiation pressure that can push away gas, while mechanical feedback consists of powerful jets and winds that can remove or heat gas in the host galaxy. Both types affect galaxy evolution by regulating star formation rates and altering the distribution of gas within galaxies. Their interactions help explain observed relationships between black hole growth and galaxy properties.
• Synthesize how AGN feedback contributes to our understanding of cosmic structure formation and evolution.
  • AGN feedback is integral to our understanding of cosmic structure formation because it highlights the interplay between black holes and their host galaxies. This relationship illustrates how energy from supermassive black holes can regulate star formation and influence galaxy morphology across cosmic time. As models incorporating AGN feedback provide insights into the connections between dark matter, gas dynamics, and stellar populations, they help to explain large-scale structures in the universe, refining our understanding of galaxy evolution in the broader context of cosmic history.

Related terms

Active Galactic Nucleus: An AGN is a compact region at the center of a galaxy that is extremely luminous due to the accretion of material by a supermassive black hole.

Supermassive Black Hole: A supermassive black hole is a black hole with a mass millions to billions of times that of the Sun, found at the center of most galaxies, including those hosting AGNs.

Interstellar Medium: The interstellar medium is the matter that exists in the space between stars in a galaxy, consisting of gas, dust, and cosmic rays.