29.03.2015 |

Episode #9 of the course “Strangest Things in Space”


Quasars are massive black holes that exist in the center of distant, and therefore ancient, galaxies. They have masses millions and sometimes billions of times greater than the sun. They are also the most luminous beacons in the sky across the entire electromagnetic spectrum. As stars and interstellar matter fall toward the quasar’s gravitationally inescapable center, the surrounding region lights up in an intense release of energy.

Quasars first became mysteries to scientists in the 1960s. Radio towers were pointed to the sky, but radio waves weren’t the only things that were picked up. Also detected were tiny but incredibly dense objects.

Due to the diversity in the conditions of the regions close to their centers, quasars exhibit a wide range of outward appearances when viewed by astronomers from Earth. Despite the wide variety of appearances, scientists have been able to label quasars with two simple quantities: the rate at which matter is falling into the quasar, and the angle at which it is seen from Earth. At first, this mere shift in angle led astronomers to believe they were looking at three different things: quasars, blazars, and radio galaxies. We now know, however, that these are all the same object, just seen from three different perspectives.

The Eddington ratio was used to explain the rate at which matter falls into this supermassive black hole. By comparing the luminosity of a quasar to its mass, we’re able to determine the rate at which material is falling into it. This ratio is also believed to play a part in the appearance of the quasars.


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