An active black hole is a black hole that it by all manner of terms is "feeding". That is, it is accreting matter, or sucking matter into itself. Most black holes are dormant and don't show any signs of accreting matter.
Let me clarify one thing... Basically, ALL galaxies, or almost all of them, have a giant black hole at their center. (If any galaxy does NOT have such a supermasive black hole, then it is likely that it had one in the past, and that it was ejected out of the galaxy.)
The center of any accumulated mass provide for an induced focus of gravitational attraction. That being said, depending on one's perspective for black hole formation, the highly active center of a young galaxy may an existing black holes or the conditions evolving toward the creation of black holes. Therefore it is conceivingly possible that stellar evolution would precede the development of a black hole within the highly active center of a young galaxy. See protogalaxy for more information.
A quasar is a very energetic distant object that is powered by a supermassive black hole at its center. The intense radiation emitted from the accretion disk around the black hole can outshine the entire galaxy in which the quasar is located.
quasar
Consider the case of a family of planets in orbit around a star. The orbital speed of each planet depends on the mass of the star and the distance of the planet from the star (presuming that the mass of the planet is negligible in comparison to that of the star). This means that if you know the speed of a planet in orbit, and you know its distance from the star, you can compute the mass of the star. Now consider an active supermassive black hole at the center of a distant galaxy. The black hole is "active" because there is matter swirling around it, being heated as it is compressed, and thus radiating light (much of it as x-rays). We can measure the speed of the material orbiting the black hole by measuring differences in the frequency of the light as the material orbits away from us on one side of the black hole and toward us on the other side. If we have a good idea of the distance to the black hole from Earth, we can calculate the distance of the material from the black hole. So we know the orbital speed of the material and we know its distance from the black hole. It is then easy to calculate how massive the black hole must be.
Active.
A central, supermassive black hole.
A blazar is an elliptical galaxy with a supermassive black hole at the center.
I believe that would be exactly the term - "active supermassive black hole". The term "active galaxy" or "active radiogalaxy" is also used for a galaxy that produces large amount of certain radiations; however, such radiation is really caused by the supermassive black hole.
Let me clarify one thing... Basically, ALL galaxies, or almost all of them, have a giant black hole at their center. (If any galaxy does NOT have such a supermasive black hole, then it is likely that it had one in the past, and that it was ejected out of the galaxy.)
A blazar is a compact quasar, associated with a super-massive black hole at the centre of an active galaxy.
For one, a black hole can hardly be observed directly (the Hawking radiation is expected to exist, but it would be way too weak). A quasar (related to material falling into the black hole) is one way the black hole can be observed.Also, the quasar can play quite an active role in the formation of a galaxy.
The center of any accumulated mass provide for an induced focus of gravitational attraction. That being said, depending on one's perspective for black hole formation, the highly active center of a young galaxy may an existing black holes or the conditions evolving toward the creation of black holes. Therefore it is conceivingly possible that stellar evolution would precede the development of a black hole within the highly active center of a young galaxy. See protogalaxy for more information.
The center of many galaxies is suspected to house a "supermassive black hole". The black hole may even weigh more than all the stars in that galaxy combined. Spiral galaxies are more likely to contain a supermassive black hole.
A Schwarzschild black hole is a non-rotating black hole. The Kerr black hole is a rotating black hole. Since the latter is more complicated to describe, it was developed much later.A Schwarzschild black hole is a non-rotating black hole. The Kerr black hole is a rotating black hole. Since the latter is more complicated to describe, it was developed much later.A Schwarzschild black hole is a non-rotating black hole. The Kerr black hole is a rotating black hole. Since the latter is more complicated to describe, it was developed much later.A Schwarzschild black hole is a non-rotating black hole. The Kerr black hole is a rotating black hole. Since the latter is more complicated to describe, it was developed much later.
A quasar is a very energetic distant object that is powered by a supermassive black hole at its center. The intense radiation emitted from the accretion disk around the black hole can outshine the entire galaxy in which the quasar is located.
A black hole originated as a star, that is, the star converted to a black hole.