Definition: Galaxy mergers occur when two or more galaxies collide and gravitationally interact, leading to the formation of a new galaxy through the merging of their stars, gas, and dust.
Types of Mergers: Galaxy mergers can be classified into different types based on the initial galaxies' shapes, such as major mergers (between similarly-sized galaxies) and minor mergers (between galaxies of different sizes).
Tidal Interactions: As galaxies approach each other, their gravitational forces cause tidal interactions, distorting their shapes and triggering the inflow of gas and dust towards the central regions.
Starburst Activity: Galaxy mergers often induce intense star formation, known as a starburst, as the colliding gas and dust clouds collapse under gravitational forces, leading to the birth of new stars.
AGN Triggering: Active Galactic Nuclei (AGN), powered by supermassive black holes at the centers of galaxies, can be triggered by galaxy mergers. The merger process feeds the central black hole, leading to enhanced accretion and the release of tremendous energy.
Morphological Transformation: Galaxy mergers can cause a morphological transformation, changing the shape and structure of the resulting galaxy. For example, mergers can create elliptical galaxies from the collision of spiral galaxies.
Stellar Streams and Tidal Tails: During galaxy mergers, tidal forces can pull stars and gas into long, slender structures called stellar streams or tidal tails. These features provide evidence of past mergers and interactions.
Galaxy Cannibalism: In some cases, a larger galaxy can consume a smaller one through a process known as galactic cannibalism. The smaller galaxy's stars, gas, and dust become part of the larger galaxy, contributing to its growth.
Simulations and Observations: Scientists use computer simulations and observations from telescopes to study galaxy mergers, exploring their dynamics, the formation of new structures, and the impact on star formation and black hole activity.
Galaxy Evolution: Galaxy mergers play a significant role in the evolution of galaxies, driving their growth, triggering star formation, influencing their morphology, and shaping the distribution of matter within galaxy clusters.