- Education and Science
Quasars The Light Houses of the Cosmos
Cosmological Enigmas: Quasars and other Deep Space questions
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In 1930 Karl Jansky a physicist working with Bell Telephone detected static interference on transatlantic phone lines which were coming from the Milky Way. Jansky then built one of the worlds first radio telescopes after many years of study he discovered that the signals were coming from the centre of the Milky Way galaxy in the constellation of Sagittarius. Astronomers continued their study into this phenomenon which they decided to call quasi-stellar radio sources or quasars for short. The first quasars were identified in early 1960’s. The term quasar was coined by Chinese –born U.S astrophysicist Hon-Yee Chiu in 1964 when writing for Physics Today in 1964 to describe these puzzling objects: “so far, the clumsily long name ‘quasi-stellar radio sources’ is used to describe these objects. Because the nature of these objects is entirely unknown, it is hard to prepare a short, appropriate nomenclature for them so that their essential properties are obvious from their name. For convenience, the abbreviated form ‘quasar’ will be used throughout this paper” – Hong Yee Chiu Physics Today May 1964.
Active Galactic Nucleus
Astronomers categories quasars as very energetic Active Galactic Nucleus .Quasars are found in a region at the centre of massive galaxies and they envelope massive black holes. Quasars are the most brightest objects in the universe they are powered by the accretion disc of super massive black holes which have more than one billion times the mass of our sun .They are the most powerful sources of electromagnetic energy including radio waves and visible light .They emit thousands of times more energy than that of our own milky way galaxy. Upon analysis quasars show a very high red shift this represents the expansion of the universe itself. If Hubble’s law is taken into account this red shift means that these quasars the light from these quasars is reaching us from across vast distance in both space and time .That means these quasars are very far away from us and sit at the edges of our known universe. This tells us that they are a phenomenon from the child hood of our universe at time when our universe was still young and evolving new structures.
Cosmic Jets of Energy
The powerful energy being emitted from quasars in the from of jets comes from gas and dust falling into a super massive black hole .Since light cannot escape from a black hole this energy is being created outside the event horizon. It is as a result of powerful gravitational forces acting upon the incoming material. These forces coming from gravitational energy are the energy released as the material is accelerated through the powerful gravitational field of a black hole. This material does not fall directly into the black hole but forms an orbit around it thereby creating an accretion disc. The material slowly spirals inward into the black hole and gets ripped apart and is heated to millions of degrees. Some of this material does not get sucked into the black hole but gets ejected at close to the speed of light. This is believed to be caused by an electromagnetic environment generated by the black hole itself .The ejected material forms two jets on opposite sides and is blasted millions of light years into deep space.
Celestial Reference Points
Meanwhile down on Earth astronomers have found a use for these quasars in the form of a celestial reference system .Because quasars are bright , extremely distant and small they can be used as reference points in instituting a measurement grid of the cosmos . The International Celestial Reference System (ICRS) is based on hundreds of extra galactic radio sources mostly quasars distributed around the entire sky. Quasars are one of the reasons that the U.S Congress in 1978 agreed to fund The Hubble Telescope. The telescope has revealed a lot about quasars especially the fact that they reside within galaxy. A lot of questions are still left unanswered like what process initiates black holes and whether their light illuminates the cosmos in all directions or is just a beam or jet that we see from earth.