Brightest mystery ever - quasar
Where's that light coming from?!
Staying on the subject of things we are not totally sure about, while the Andromeda galaxy is the most distant thing your eyes can detect, pretty well the most distant things we can detect in detail using telescopes are quasars. When they were first discovered it was thought that quasars (shortening of 'quasi-stellar object) were distant stars, but the color spectrum of the light coming from them didn't seem right. It was too red.
When objects in space move towards us, theirs light gets an increase in energy - it is blue shifted. And when they move away, their lower energy light is red shifted. The light from quasars is shifted a long way into red. Because of the expansion of the universe over time, the further something is away, the greater its redshift. The first quasar to be studied, back in 1960s, turned out to be (at the time) the most distant object ever observed. Yet its brightness was comparable with a star in our own galaxy.
After more study with better instruments it was discovered that quasars emit as much light as a whole galaxy from an area that can be as small as our Solar System.
Structure of a quasar
Our own galaxy Milky Way was at some point a "Milky quasar". Actually almost all galaxies many years ago were or still are quasars. In other words quasar is a very young, still forming galaxy. But these juvenile galaxies are strange and very different from other more mature galaxies.
Imagine a black hole that is constantly being fed with enormous, endless portions of matter. This matter - gas clouds and other material required for a galaxy to form - is accelerating to near the speed of light because it is getting closer to the center of the black hole were unimaginably strong gravitational pull forces matter to spin around black hole's center. With a mature galaxy, like our Milky Way, that black hole will have dragged in all the nearby debris, but in a young galaxy it will still be pulling in nearby material.
It's all this material, accelerated to near light speed as it plunges towards the black hole, that is thought to give off the quasar's dramatic blaze of light.
Strongest jets in the universe
Many quasars have a pair of 'jets': very energetic streams of glowing material, gas and radiation spurting out from either side of it. This gas and material is shot out from the quasar at such speed and force that it can travel many light-years away from it.
All this stuff black hole is spitting out is vital for a formation of a star. Many cosmologists believe that by possessing all this matter (black holes can actually change the portion of thrown out material and gas) center black hole controls growth of the galaxy around it.
Black hole has a sphere of material orbiting around it, spinning with the black hole and prevented from plunging into it by its spin. At the poles there will be no spin to speak of, leaving gaps through which material could be blasted.
The most extreme environment
After matter passes black hole's event horizon it is now moving towards the singularity (black hole's center) faster than the speed of light. But getting closer and closer to the center it starts experiencing mind-boggling reality of the black hole. Space itself is wrapped so tightly that it doesn't make sense anymore. At some point near the singularity particles of matter start coming out of the black hole (or spinning in different direction if you like) and collide with the ones coming into it (spinning along normal path). At the point they meet each other, unimaginably large energy portions, traveling against each other faster than light speed face one another. Inside a black hole energy does not dissipate. Instead it builds on itself rising to an extreme state. This collision produces something’s what is called - Planck density. If you want to visualize and understand how subnormal it is, imagine taking all the matter we are aware of, all the trillions upon trillions of stars that make up all the galaxies in the universe and crush it down to the size of an atom. That is Planck density. And such density is created inside a black hole only because of its dramatically environment.
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Facts about quasars
- There are quasars that emit as much light as several billions of Suns.
- Some of the quasars we can detect with our telescopes have died thousands of years ago, but Earth is still receiving their light because it has to travel unimaginably long distances and it takes time!
- Some of the quasars are visible to the naked eye although they are at the halfway of the whole visible universe.
- When two quasars meet each other, black holes in the middle of them start pulling each other. Then they begin spinning around one another until the bigger one pulls smaller one inside. This spinning period can last millions of years and it dramatically affects space and time near the quasars.
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