A radio galaxy whose lobes are swept back as if forming a tail probably indicates that:
A)this is evidence for intergalactic matter.
B)the galaxy is about to evolve into a spiral.
C)the galaxy is isolated, not part of a cluster.
D)the galaxy is moving towards Earth.
E)there must be another galaxy nearby.

Question

Quizplus · Accepted Answer

The sweeping back of the lobes suggests that there is intergalactic matter present that is causing resistance to the motion of the radio galaxy, creating the tail-like shape. The swept back lobes on a radio galaxy indicate that there is some resistance in the medium through which the galaxy is moving. This resistance is often caused by intergalactic matter, such as gas and dust. Therefore, this is evidence for the presence of intergalactic matter.

A Radio Galaxy Whose Lobes Are Swept Back as If