Question

What is believed to be the origin of giant elliptical galaxies? question 13 select one:

a. they grew by devouring smaller galaxies in galactic cannibalism.
b. they have grown continuously since their formation, by accretion intergalactic gas.
c. collisions between galaxies in the cluster produce a smooth distribution of stars throughout the cluster; these sink by gravity to the cluster center and form giant elliptical galaxies.
d. they formed that way and have remained unchanged ever since.

Answer 1

Giant elliptical galaxies primarily formed through the collision and merger of smaller galaxies, a process sometimes referred to as 'galactic cannibalism'.

Step-by-step explanation:

The origin of giant elliptical galaxies is a complex process that involves multiple mechanisms. A key understanding in astrophysics is that most giant elliptical galaxies formed through the collision and merger of many smaller fragments in a process described as 'galactic cannibalism'. Slow collisions and mergers have also been known to transform spiral galaxies into elliptical galaxies. These mergers often involve galaxies that have already formed stars, indicating a 'bottom-up' scenario. There is evidence that some giant ellipticals may have begun their evolution early through the collapse of a single large cloud, but also that they have not formed many new stars in recent times and mostly contain old stars, leading to them being labeled as 'red and dead'.

Overall, observations suggest that giant elliptical galaxies likely formed from a combination of top-down and bottom-up processes, particularly in the densest clusters of the universe where the formation happened very early and quickly.