Mankind’s Explanation: Quasars


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    Quasars  a contraction of quasi-stellar and a popular name for quasi-stellar objects in general.  Quasars may be the strangest objects in the universe.  In photographs they look like ordinary stars, but closer examination shows them to be immensely luminous and perhaps the most distant objects known.  Quasi-stellar object (QSO) is the general term, and quasi-stellar source (QSS), or quasi-stellar radio source, refers to quasars that have detectable radio emission. 

   Theories of Quasar Phenomena.  Most astronomers prefer the hypothesis that redshifts are due to high velocities of recession and that these velocities follow the Hubble relation, implying enormous distances and luminosities (10 to 100 times the energy output of giant galaxies) probably from relatively small areas.  This view is favored because several quasars have been observed near galaxies of the same redshift.

   Inspired by a desire to evade the prodigious energy requirements, some astronomers suggest that the quasars are closer--well outside our own galaxy but within the region of known galaxies--so that these energy requirements may be drastically reduced.  Some unknown physical mechanism would have to be invoked to explain the redshifts if quasars are not receding at high velocities (Gravitational redshifts have been suggested but are not consistent with observations.)

   In some hypotheses it is proposed that quasars are rapidly receding fragments of a stupendous “local” cosmic explosion.  There is no evidence that such an explosion has occurred in our galaxy, and further restrictions can be placed on this theory by the absence of detected proper motions (cross motions in the sky) or of blueshifts resulting from any hypothetical explosion fragments come toward us.  Such theories must contend with the enormous energy required of the local explosion in order to eject thousands of solar masses at speeds approaching that of light.  Thus these theories are confronted by the very problems they were designed to escape.

   If the quasars are enormously distant, all hypotheses require between millions and billions of solar masses present in a basic energy source less than a few light-years across to account for such staggering generations of power.  It is possible that these concentrations of mass occur at the centers of giant galaxies.

One hypothesis is that power is generated by the annihilation of matter and antimatter with subsequent production of electrons, positrons, neutrinos, and gamma rays.  Apart from problems involved in the free existence of antimatter, this hypothesis requires enormous amounts of energy to accelerate the particles necessary to produce the observed synchrotron radiation.

Other hypotheses depend on the release of gravitational potential energy and fall into three categories: supernova explosions or stellar collisions in dense star clusters, collapse or pulsation of super massive stars, and accretion of matter onto massive black holes.  Provided that the masses involved are greater than 10 million solar masses, a massive black hole is expected to result from the evolution and subsequent collapse of a dense star cluster or super massive star.” 

Bibliography:  Swarup, G., and V.K. Kapashi, eds., Quasars (Kluwer 1986). 

Information acquired from within the quotes is from: Encyclopedia Americana - International Edition Copyright 1994 Grolier Incorporated, Volume 23, pages 60-61 

   “QUASAR.  Since their discovery in early 1960’s, quasars, or quasi-stellar radio sources, continue to baffle astronomers.  It is now generally accepted that quasars are the highly luminous cores, or nuclei, of distant galaxies.  What is still uncertain about quasars is how they produce their vast energy.  They are up to a thousand times as bright as the average galaxy. 


   From the degrees of its red shift, a quasar’s distance from the Earth and the speed at which it is receding can be calculated.  Such calculations have indicated that many quasars are receding at speeds approaching that of light and that their distance from the Earth is enormous. Some appear to be as far away as 14 billion light-years, so distant that they may mark the horizon of the known universe. 

   The size of quasars is believed to be relatively small, about one or two light-years in diameter.  This is surprising because the luminosity of a quasar is anywhere from 10 to 1,000 times greater than that of any normal galaxy.  Quasars emit a huge amount of energy as X rays, ultraviolet rays, radio waves, and other forms of electromagnetic radiation.

   Astronomers have no generally accepted explanation for how such massive amounts of power are generated, but there is no lack of theories.  Many investigators theorize that the central energy source may have its origin in gas spiraling into a massive black hole--a collapsed star with such great gravitational force that not even light can escape.” 

Information acquired from within the quotes is from: Compton’s Encyclopedia Online v.3.0 (c) 1998 The Learning Company,


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