Quasars

Definition

Quasars are extremely luminous active galactic nuclei powered by supermassive black holes at their centers. They emit vast amounts of energy, often outshining entire galaxies.

5 Must Know Facts For Your Next Test

1. Quasars are among the most distant and oldest objects observed in the universe, providing clues about the early stages of cosmic evolution.
2. The energy output of quasars is primarily due to accretion of matter onto supermassive black holes, converting gravitational energy into electromagnetic radiation.
3. Quasars exhibit high redshifts, indicating that they are moving away from us at significant fractions of the speed of light due to the expansion of the universe.
4. They can be used as cosmic lighthouses to study intergalactic space and map out large-scale structures in the universe.
5. The first quasar discovered was 3C 273 in 1963, which helped establish the existence of these powerful astronomical objects.

Review Questions

• What powers the immense luminosity observed in quasars?
• Why do quasars exhibit high redshifts, and what does this imply about their movement relative to Earth?
• How can quasars be used to study large-scale structures in the universe?

Related terms

Active Galactic Nucleus (AGN): A region at the center of a galaxy that is extremely bright due to energetic processes around its supermassive black hole.

Redshift: The phenomenon where light from an object is shifted towards longer wavelengths as it moves away from an observer, commonly used to measure cosmic distances.

Accretion Disk: A rotating disk of gas and dust surrounding a central massive object, such as a black hole, where material is gradually pulled inward.