What is a Quasar?
The word “quasar” refers to a “quasi-stellar radio source.” The first quasars were discovered in the 1960s when astronomers measured their very strong radio emissions. Later, scientists discovered that quasars are actually radio-quiet, with very little radio emission. However, quasars are some of the brightest and most distant objects we can see. These ultra-bright objects are likely the centers of active galaxies where supermassive black holes reside. As material spirals into the black holes, a large part of the mass is converted to energy. It is this energy that we see. And though smaller than our solar system, a single quasar can outshine an entire galaxy of a hundred billion stars. To date, astronomers have identified more than a thousand quasars.
Quasars (QUASi-stellAR radar sources) are gigantic luminous bodies between 780 million and 13 billion light years away, and correspondingly old. They are thought to be active galactic nuclei containing a central supermassive black hole. The brightest quasars are 2 trillion times brighter than our sun, or about 100 Milky Way galaxies. Their light output is continuous but can fluctuate in intensity on timescales of years, months, weeks, days or even hours, suggesting that they are quite dense. Even as recently as the 1980s, there was significant disagreement among astrophysicists as to what quasars really are. A scientific consensus emerged when some quasars were found to be surrounded by galaxies, originating the active galactic nucleus theory. It has been calculated that, to generate the amount of light that they do, quasars must be powered by supermassive black holes that swallow between 10 and 1000 solar masses per year. In the accretion disc of such a black hole, superheated gases a
We still do not know exactly what a quasar is. But the most educated guess points to the possibility that quasars are produced by super massive black holes consuming matter in an acceleration disk. As the matter spins faster and faster, it heats up. The friction between all of the particles would give off enormous amounts of light other forms of radiation such as x-rays. The black hole would be devouring the equivalent mass of one Sun per year. As this matter is crushed out of existence by the black hole, enormous amounts of energy would be ejected along the black hole’s north and south poles. Astronomers refer to these formations as cosmic jets. Another possible explanation for quasars is that they are very young galaxies. Since we know very little about the evolutionary process of galaxies, it is possible that quasars, as old as they are, represent a very early stage in the formation of galaxies. The energy we see may be ejected from the cores of these very young and very active gala
Quasars are violent, extremely luminous galaxies. There are many types of active galaxies (Seyfert galaxies and radio galaxies for two), but quasars trump them all in power and brightness. The light we see from a quasar is from synchrotron radiation and occurs from electrons moving close to the speed of light in a strong magnetic field.
