Answer:
an active galaxy is the galaxy that produces large amounts of energy in a very small volume of space.
Step-by-step explanation:
active galaxies such as the M87 gives out extremely bright straight jets having speeds close to the speed of light providing the evidence that power in active galaxies is concentrated in a small region. this power from such a small region cannot be generated throught nuclear fusion as it happens in stars, this is the region why the concentration of matter in the center of this galaxies is not made up of stars.