Category: Virtual Observatory

Missing Black Holes Driven Out

May 28, 2004

Active galaxies are breathtaking objects. Their compact nuclei are so luminous that they can outshine the entire galaxy; ''quasars'' constitute extreme cases of this phenomenon, their powerful engine making them visible over a very large fraction of the observable Universe. It is now widely accepted that the ultimate power station of these activities originates in supermassive black holes with masses up to thousands of millions times the mass of our Sun. For comparison, the one in the Milky Way galaxy has only about 3 million solar masses. The central black hole is believed to be fed from a tightly wound accretion disc of gas and dust encircling it, in a donuts-shaped torus. Material that falls towards these gigantic ''vacuum cleaners'' will be compressed and heated up to enormous temperatures. This hot gas radiates an incredible amount of light, causing the active galaxy nucleus to shine so brightly.