Far out in the universe there are dots of objects that emit a very intense radiation, these dots look like stars, but that is not what they are. They are objects that can not be distinguished from stars (or quasistellar) objects: quasars.
Radiation
from the past.
The quasars are found in the farthest parts of the universe as tiny spots
from where a very intense radiation is emitted. There are still a lot of questions to be answeres about the existence of quasars.
Some quasars, like the one on the far left, we
see two images in the sky (the green area) from Earth (which is on the right).
We do not only observe the light that comes to us in a straight line from
the quasar, however also the light that branches off due to gravity
of a galaxy that is positioned in between.From this we know that the quasar lies far behind the
star galaxy.
source: David Parker/Science Photo Library, London.
As far as we know, these objects are very distant, extremely
energetic and active nuclei of galaxies,
that move away from us at very high velocities.
The galaxies that are drifting away from us are not so peculiar, they fit
in our view of the expanding
universe. Quasars however, appear to move much faster than 'normal'
galaxies. Measurements based upon the Doppler
effect indicate that some quasars fly away from us with velocities
of more than 90% of the velocity of light and that they are at distances
of at least 14 billion lightyears. This is the largest distance
ever observed in the universe. It took the light of the quasars 14 billion
years to reach us, this means that we see the quasars in the status as
they where during almost the beginning
of the universe (the universe came into being about 15 billion years
ago). From the quasars we can learn a lot about the earliest period of
the universe.
Super
radiation.
Quasars emit their radiation as visible
light as well as röntgen radiation. A typical property of quasars
is the variability of their
radiation. The intensity of it may vary clearly within months, days,
hours and even sometimes minutes. Irregularly they are visible, as if a
cloud is travelling before the Sun.
From this phenomenon we can derive that quasars are relatively small,
they cannot be larger than some light-months or sometimes light-days
in diameter, at largest just as large as the period of light variation.
When we compare this with the sizes of the galaxies,
they reach sizes of many thousands and sometimes even hundreds of thousands
of lightyears. They are relatively
small objects, often more or less as large as our planetary systems (the
diameter of our planetary system is approximately one half light day).
Still they emit extremely
intense radiation , they reach luminosities between one hundred and one
thousand times that of the brightest galaxies, and often contain between
10 to 100 billion stars. The emission of strong
radiation requires very large quantities of energy, the quasars have
a yearly consumption of several sun masses
of matter. It is assumed that quasars emitted their radiation during
several millions of years. All together up to now, quasars have
used hundreds of millions of sun masses of matter as energy. How
this energy is generated is still an unresolved question.
Galaxies
of prehistoric times?
It is assumed that the quasars may be very large black
holes, or possible the nuclei of galaxies where by chain reaction hundreds
of millions of supernova occur.
At the start of the universe there may have been thousands of such
galaxies with super active stars in the center, today these are
all transferred into 'ordinary' galaxies. Only the farthest
galaxies are still visible, we can still see them in the shape as they
were in the early period of
the universe.
Another theory says that we are observing a prehistoric event of the
universe, the unification of
matter with anti-matter, even before the galaxy formation took
place.