Monday, June 9, 2008

Radio Astronomers Detect ''Baby Quasar''

An international group of radio astronomers has found an unexpected morphology in the most distant radio quasar ever. This was done using the world's most sensitive network of radio telescopes called the European VLBI Network (EVN). The results of their discovery are published in the Astronomy and Astrophysics journal on 5 June. Quasars are the most powerful 'engines' in the Universe. Observed with a radio telescope they look like stars, but they are much farther away from Earth. Because they are so powerful, their light can be seen by modern telescopes from distances comparable with the size of the Universe. The observation of the newly found quasar was conducted with ten radio telescopes in Europe (including the Westerbork Synthesis Radio Telescope in the Netherlands), China and South Africa, at the frequency of 1.6 GHz (wavelength of 18 cm). The quasar, called J1427+3312, can be seen in the image. It shows a double morphology and the components are about 480 light years apart. This kind of double morphology, combined with a steep radio spectrum, is typical for young radio sources. What makes the quasar in the picture so interesting is its extremely distant location. It is so far away from our Galaxy that it takes the light it emits more than 90% of the age of the Universe to reach us. In other words, what we see corresponds to the time when the Universe was less than 10% of its present age. Being so distant, the quasar J1427+3312 is located relatively close to the inner edge of the so called Epoch of Reionisation (EoR) - the cosmological 'Dark Ages'. In a sense, the EoR is responsible for the appearance and composition of the Universe we live in - the variety of galaxies, stars and, ultimately, planets. The reionisation is one of the most tantalizing subjects for investigations with the next generation of radio telescopes, LOFAR and the Square Kilometre Array (SKA).

Currently Dutch efforts in radio astronomy focus largely on the implementation of LOFAR and SKA. The quasar J1427+3312, in the words of Leonid Gurvits, Senior Astronomer at the Joint Institute for VLBI in Europe (JIVE, Dwingeloo, the Netherlands), is "a powerful lighthouse that happens to be located at the place where we want to light up surroundings in search for something terribly important; one day, with new radio telescopes, we will 'use' this lighthouse as a handy tool in the search for EoR signatures.

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