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|Date: Thursday 1 October 1998
Embargo: For immediate release
The brightest object yet observed in the Universe, APM08279+5255, has been discovered by an astronomer at the Royal Greenwich Observatory and his colleagues using the ING telescopes Isaac Newton and Jacobus Kapteyn. Their findings have been published today in the Astrophysical Journal.
APM08279+5255 is an extremely bright quasar
(quasi-stellar object) four to five million, billion times brighter than
the Sun and about 100 times brighter than the next brightest object that
has been observed. It was discovered serendipitously as part of a survey
for cool giant carbon stars in the halo of the Milky Way. The nature of
the quasar was only revealed when a spectrum
of the light from it was analyzed.
Dr. Mike Irwin an astronomer at the Royal Greenwich Observatory, together with his collaborators: Rodrigo Ibata of the European Southern Observatory in Munich, Edward Totten of Keele University and Geraint Lewis of the University of Washington, made the discovery observations on the 2.5-meter Isaac Newton Telescope and the 1.0-meter Jacobus Kapteyn Telescope on La Palma in the Canary Islands, on February 28th this year.
The only way such a huge amount of energy could be generated is from accretion of dust and gas particles onto a super massive black hole, located at the center of the quasar. The object's apparent brightness actually comes from two different regions around the black hole. Light in the ultraviolet and optical range comes directly from an accretion disk surrounding the super massive black hole. Gas and dust and even entire stars are attracted by the black hole's gravitation and generate energy, including light, from friction as they are torn apart and fall toward the black hole.
The second source of brightness, in the infrared portion of the spectrum, comes from dust further away from the central engine, which is heated by radiation from the center of the quasar and which re-radiates this radiation at much longer wavelengths in the infrared.
Quasars are generally the most energetic objects observed in the Universe. Each quasar generates more energy than the rest of a galaxy's stars combined. Yet a quasar, its accretion disk and the glowing dust surrounding it occupy a relatively small amount of space, not much larger than the size of the Solar System.
Most quasars are not bright enough to reveal this strong infrared signature. However a few, much closer, ultra luminous galaxies have similar properties. By comparing the newly discovered object with these fainter nearby well studied examples, Irwin and his team have weighed the amount of dust in the object and find a staggering value of almost a billion solar masses. This is more than the entire dust mass in the Milky Way, yet has been created and accreted in a small fraction of the time and is contained in a volume the size of the Solar System.
Finding an object of this energy level will help scientists understand more about what fuels quasars. Irwin and his colleagues are trying to gather more data, including high resolution Hubble Space Telescope images, to develop an understanding of the complete spectrum of energy from this object. They hope to investigate the physics to the various components, which will shed light on what is happening in the quasar. Ultimately, information like this helps astronomers develop a more accurate picture of the Universe's origins and its structure.
Since this quasar is such a powerful beacon of light and has traveled 11 billion light years, it can also be used to investigate intervening objects that leave an imprint on the light from the quasar. By studying these imprints astronomers can learn what conditions in the early Universe were like and measure how primordial gas was converted into the stars and galaxies that we see around us today.
It is possible that some of these intervening absorbing systems may have acted as giant gravitational lenses and magnified the light from the quasar. Gravitational lenses are often seen to be the cause of apparently extremely bright objects. Typically, such a lens might exaggerate the real light level by a factor of 30 or 40, which however in this case, would still make APM0827+5255 an order of magnitude brighter than its nearest competitor.
The Isaac Newton Group of telescopes (ING) consists of the 4.2m William Herschel Telescope, the 2.5m Isaac Newton Telescope and the 1.0m Jacobus Kapteyn Telescope. The ING is owned and operated jointly by the UK's Particle Physics and Astronomy Research Council (PPARC) and the Netherlands' Nederlandse Organisatie voor Wetenschappelijk Onderzoek (NWO). The telescopes are located in the Spanish Observatorio del Roque de Los Muchachos on La Palma which belongs to the Instituto de Astrofísica de Canarias (IAC).
Quasar: A compact extra-galactic object that
looks like a point source of light but emits more energy than a hundred
Press Photo ING PP1/98 shows APM 08279+5255 and other plots of interest.
FOR FURTHER INFORMATION CONTACT:
Dr. Mike Irwin
Javier Méndez Alvarez