Intergalactic medium

Definition

The intergalactic medium is the matter that exists in the space between galaxies, primarily composed of hot ionized gas, cold gas clouds, cosmic dust, and dark matter. It plays a critical role in the universe's structure and evolution, acting as the reservoir for gas that can fuel star formation in galaxies and influencing the dynamics of galaxy interactions.

5 Must Know Facts For Your Next Test

1. The intergalactic medium is estimated to contain about 10% of the total baryonic (ordinary) matter in the universe.
2. It consists mostly of hot ionized hydrogen gas at temperatures reaching millions of degrees, which emits X-rays detectable by space telescopes.
3. Cold gas clouds within the intergalactic medium can collapse under gravity to form new stars, highlighting its role in galaxy evolution.
4. The intergalactic medium influences the formation and evolution of galaxies by acting as a source of material for star formation and recycling gas expelled by supernovae.
5. Interactions between galaxies can disturb the intergalactic medium, leading to phenomena like shock waves and filamentary structures that affect galaxy dynamics.

Review Questions

• How does the intergalactic medium contribute to star formation within galaxies?
  • The intergalactic medium serves as a reservoir of gas that can collapse under gravity to form new stars. As galaxies evolve, they can draw material from this medium to replenish their own gas supplies. Additionally, processes like supernovae can eject gas back into the intergalactic medium, enriching it with elements formed in stars and making it available for future star formation.
• Discuss the significance of the temperature and composition of the intergalactic medium in understanding cosmic structure.
  • The temperature and composition of the intergalactic medium are crucial for understanding the universe's large-scale structure. The hot ionized gas, primarily hydrogen, emits X-rays that provide insights into the distribution and density of matter between galaxies. By studying these characteristics, astronomers can infer how galaxy clusters form and evolve over time, revealing important aspects of cosmic history.
• Evaluate the role of dark matter in shaping the intergalactic medium and its influence on galaxy formation.
  • Dark matter plays a pivotal role in shaping the intergalactic medium by providing the gravitational framework that governs how matter is distributed in space. Its presence affects the density and temperature of the intergalactic gas, impacting how it interacts with visible matter. This interaction influences galaxy formation, as dark matter halos help gather gas from the intergalactic medium, ultimately leading to star formation and galaxy growth. Understanding this relationship deepens our knowledge of cosmic evolution.

Related terms

Cosmic Microwave Background: The residual thermal radiation from the Big Bang, filling the universe and providing evidence for its hot early state.

Galaxy Cluster: A large group of galaxies bound together by gravity, often containing significant amounts of intergalactic medium between the member galaxies.

Dark Matter: A form of matter that does not emit light or energy, making it invisible and detectable only through its gravitational effects on visible matter.