Dispatches from Planet 3 by Marcia Bartusiak

Author:Marcia Bartusiak
Language: eng
Format: epub
ISBN: 9780300240580
Publisher: Yale University Press

An image of 3C 273, the first identified quasar,

taken by the Hubble Space Telescope.

(ESA/Hubble & NASA)

3C 273 is now considered relatively close to us, as quasars go. Its distance is small potatoes compared with those of later finds. Today’s record holders are more than six times as far away. And the fact that earthbound observers are able to photograph such quasars across the vastness of the universe means that these objects are the most powerful denizens of the heavens.

What could possibly be the source of a quasar’s monstrous energy? That’s the first thing everyone asked when 3C 273’s secret was revealed. “The insult was not that they radiate so much energy,” said Schmidt, “but that this energy was coming from a region probably no more than a light-week across.” Astronomers came to know this by seeing the quasars dim and brighten over a matter of weeks or days. In the case of 3C 273, they checked old photographic plates of the 13th-magnitude object, going back some seventy years. In one picture it was faint, a month later it was brighter. Such relatively swift and sizable fluctuations meant that the quasar’s power source was small, perhaps less than the diameter of our solar system. (Any small luminosity change in a vastly larger object would get lost in the noise.) Yet from such a cosmically tiny region spewed the energy of billions of suns. Tapping into such a cosmic dynamo for just one second would power the world for a billion billion years.

Since Schmidt’s discovery, quasars have been closely examined by an array of telescopes—radio, infrared, optical, and X-ray. And all point to one answer to a quasar’s identity: it’s a supermassive black hole residing in the center of a young, gas-filled galaxy. The vast energies are likely released as matter spirals in toward the black hole, and also by the spinning hole itself acting as a powerful dynamo, causing huge beams of energy to shoot out of the black hole’s north and south poles.

The center of our home galaxy, the Milky Way, was probably a quasar in the distant past. The black hole lurking there, estimated to contain the mass of around four million suns, is now fairly quiet, having grabbed all the nearby “food” it can get. Its engine is on idle, but this behemoth might wake up one day, perhaps as we slowly collide with our close neighbor, the Andromeda galaxy, about four billion years from now.

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