Astronomers say there’s nothing special about two qusars – named RXJ1131-1231 and Q2237+0305 – except that a massive galaxy lies between them and us. The intervening galaxy acts as a lens to magnify the quasars’ structure. Astronomer Xinyu Dai at Ohio State University and his colleagues have managed a first glimpse inside a quasar.
Xinyu Dai: Quasars are objects that are very far away. Because they are so far away, when we look at them far away, directly, by imaging, they all look like little dots.
Quasars are distant, but we see them because they’re bright. The brightest one shines some two trillion times more powerfully than our sun. Astronomers believe that a quasar’s tremendous brightness stems from a central black hole. They think space dust and gas are sucked into the hole at close to the speed of light. This debris flares up and creates the brilliant light of quasars. Xinyu Dai told EarthSky about measuring the size of the disk of debris – what’s called the accretion disk – surrounding a black hole inside two quasars.
Xinyu Dai: The quasar has structure in it, and we couldn’t know that before. Now we can actually map the structure of quasar accretion discs.
Dai said both disks measure about 10 astronomical units in width, about 10 times the Earth-sun distance. In contrast, the quasars themselves are about a million billion astronomical units from Earth. He said that, before this research, there were many models that tried to describe what is happening inside a quasar. Before, none of them could be ruled out. Now some of them can.
The fact is that quasars are billions of miles away, so far away that even in the most advanced telescopes, they look like a tiny pinpoint of light. These astronomers used the fact that a massive galaxy lies between us and the quasars they studied. The intervening galaxy magnified the light like a lens, in an effect known as gravitational lensing. The astronomers likened the effect to being able to look at the quasars under a microscope.
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Our thanks to:
Xinyu Dai
Ohio State University
This is a question from a complete layman. If quasars are a trillion times brighter than our sun, what distance would we need to be from such an astronomical body in order to experience the same light levels we get from the sun.
Thank you
Rob
Dear Rob,
We asked our science advisor, astronomer Derek Wills of U.T. Austin, your question.
In a nutshell, it turns out that a quasar would be as bright as the sun if you were about 16 light years away from it.
A light year is the distance that light travels, in the vacuum of space, in a whole year. By comparison, our sun is only about eight light minutes away from Earth.
The rule that governs brightness is called the inverse square law. Brightness is inversely proportional to the square of the distance from the source of light. So an object that’s twice as far away from a light source as another would see that light to be about a quarter as bright.
Another way to put it is as Dr. Wills said, “if such an object (the quasar) were at the distance of the closest star outside the solar system, it would appear about 15 times brighter than our sun does now.”
Hope that helps,
Jorge
Hi Jorge,
Thank you very much for your facinating answer; 16 light years! Quite amazing!
I have another question relating to stars etc; again I must admit to it being asked by a complete layman. If I understand correctly, there appears to be bits of space missing or not enough material or somesuch—not enough dark matter? Is it possible that it might have disappeared down a Black Hole?
Thanks
Rob
Don’t know if anyone views this thread anymore, but is this a possible simplistic view of the evolution of the universe:
1. Big bang is non-uniform so early universe is “lumpy” – and the lumps are multi-million solar mass black holes.
2. Black holes pull in matter and form quasers.
3. Accretion disks form around black holes and eventually become galaxies as the system stabilizes – i.e. the central black hole pulls in all the matter it can, so the quaser dies out and stars form in the accretion disk.
If this is plausible, is there any explanation for the different types of galaxies? Has anyone ever correlated galaxy type to age?
Thanks!