European researchers have discovered 30 supermassive black holes which had been veiled by dust in the past making their discovery difficult. They are so far away that the galaxies they anchor are also difficult to examine in detail.

"This discovery means that surveys of powerful supermassive black holes have so far underestimated their numbers by at least a factor of two, and possibly by up to a factor of five," said study leader Paolo Padovani.

Images from the Hubble Space Telescope, the Chandra X-ray Observatory and the European Southern Observatory's Very Large Telescope in Chile, were used to make the discoveries, they make up a database at the Astrophysical Virtual Observatory.