What is the activity of galaxies?

The activity of galaxies manifests itself in the outflow of gas or strong radio emission from the nucleus. The eruption of gas is about one solar mass per year.
In the past, there were many more active galaxies. Quasars are believed to be very active galaxies located at cosmological distances. The core of a quasar can be a black hole, billions of times larger in mass than the Sun. Quasars radiate over the entire electromagnetic range with tremendous power.

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