Chapter 16

Question 1

Starburst galaxy

Answer 1

Galaxy in which a violent event, such as near collision, has caused an intense episode of star formation in the recent path.

Question 2

Hierarchical merging

Answer 2

Widely accepted galaxy-formation scenario in which galaxies formed as relatively small objects in the early universe and subsequently collided and merged to form the large galaxies observed today. The present Hubble type of a galaxy depends on the sequence of merger events in the galaxy’s past.

Question 3

Quasar feedback

Answer 3

The idea that some of the energy released by a quasar in an active galactic nucleus heats and ejects the gas in the surrounding galaxy, shutting off the quasar fuel supply and suppressing star formation in the galaxy, connecting the growth of the central black hole to the properties of the host galaxy.

Question 4

Superclusters

Answer 4

Grouping of several clusters of galaxies into a larger, but not necessarily gravitationally bound unit.

Question 5

Voids

Answer 5

Large, relatively empty regions of the universe around which superclusters and “Walls” of galaxies are organized.

Question 6

Twin quasar also known as the mirages