Minor Merger

Definition

A minor merger is a type of galaxy merger where a smaller galaxy is absorbed by a larger, more dominant galaxy. This process is an important mechanism for the growth and evolution of galaxies over cosmic time.

5 Must Know Facts For Your Next Test

1. Minor mergers are less dramatic than major mergers, where two galaxies of comparable size collide and eventually form a new, larger galaxy.
2. During a minor merger, the smaller galaxy is typically disrupted and its stars and gas are incorporated into the larger host galaxy, contributing to its growth.
3. Minor mergers can trigger an increase in the star formation rate of the host galaxy, as well as potentially activating its central supermassive black hole, leading to the formation of an Active Galactic Nucleus (AGN).
4. Dynamical friction plays a crucial role in minor mergers, causing the smaller galaxy to lose kinetic energy and angular momentum, ultimately leading to its merger with the larger host galaxy.
5. Minor mergers are believed to be more common than major mergers in the universe, and they are an important driver of galaxy evolution, shaping the structure and properties of galaxies over cosmic time.

Review Questions

• Explain how a minor merger differs from a major galaxy merger, and describe the key processes involved in a minor merger.
  • A minor merger is a type of galaxy merger where a smaller galaxy is absorbed by a larger, more dominant galaxy. This is in contrast to a major merger, where two galaxies of comparable size collide and eventually form a new, larger galaxy. In a minor merger, the smaller galaxy is typically disrupted, and its stars and gas are incorporated into the larger host galaxy, contributing to its growth. Dynamical friction plays a crucial role in the minor merger process, causing the smaller galaxy to lose kinetic energy and angular momentum, leading to its eventual merger with the larger host galaxy.
• Discuss the potential impact of a minor merger on the host galaxy, including changes in star formation rate and the activation of the central supermassive black hole.
  • Minor mergers can have significant impacts on the host galaxy. The influx of gas and stars from the smaller galaxy can trigger an increase in the star formation rate of the host galaxy, as the additional material provides fuel for new star formation. Additionally, the minor merger can potentially activate the central supermassive black hole of the host galaxy, leading to the formation of an Active Galactic Nucleus (AGN). The increased activity of the central black hole can have far-reaching consequences, influencing the overall structure and evolution of the host galaxy. These changes in star formation and black hole activity are important drivers of galaxy evolution, shaping the properties of galaxies over cosmic time.
• Explain the role of dynamical friction in the context of minor mergers and how it contributes to the eventual merger of the smaller galaxy with the larger host galaxy.
  • Dynamical friction is a crucial process in the context of minor mergers. This force acts on the smaller galaxy as it moves through the gravitational field of the larger host galaxy, causing it to lose kinetic energy and angular momentum. As the smaller galaxy decelerates due to dynamical friction, it gradually spirals inward, eventually merging with the larger host galaxy. This loss of energy and momentum is a key driver of the minor merger process, allowing the smaller galaxy to be incorporated into the larger galaxy over time. Dynamical friction is an important mechanism that facilitates the growth and evolution of galaxies through the accretion of smaller companion galaxies.

Related terms

Galaxy Merger:

A galaxy merger is the combining of two or more galaxies due to gravitational attraction, leading to the formation of a new, larger galaxy.

Active Galactic Nucleus (AGN): An active galactic nucleus is a compact region at the center of a galaxy that is extremely luminous and is believed to be powered by a supermassive black hole.

Dynamical Friction: Dynamical friction is a force that acts on a massive object moving through a medium, causing it to lose kinetic energy and angular momentum, leading to the object's deceleration and eventual merger.