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

Question

Quizplus · Accepted Answer

Radio galaxies with lobes that appear swept back, resembling a tail, suggest the presence of intergalactic matter. As the galaxy moves through this medium, the interaction between the radio lobes and the intergalactic matter causes the lobes to appear swept back due to the relative motion between the galaxy and the surrounding medium.

A Radio Galaxy Whose Lobes Are Swept Back as If