Scientists at the University of Cambridge said the black holes were previously undetected because they sit cocooned within thick layers of dust, but have been spotted because they are emitting vast amounts of radiation through violent interactions with their host galaxies.
Writing in the journal Monthly Notices of the Royal Astronomical Society, astronomers said the most extreme object found in the survey is a supermassive black hole called ULASJ1234+0907, so far away the light from it has taken 11 billion light years to reach us, so we see it as it appeared in the early universe.
It is more than 10 billion times the mass of the Sun and 10,000 times the mass of the supermassive black hole in our own Milky Way, making it one of the most massive black holes ever seen, they said.
"Although ... black holes have been studied for some time, the new results indicate that some of the most massive ones may have so far been hidden from our view," lead study author Manda Banerji said.
The Cambridge team used infrared survey data from the U.K. Infrared Telescope to peer through the dust and locate the giant black holes for the first time.
"These results are particularly exciting because they show that our new infrared surveys are finding super massive black holes that are invisible in optical surveys," researcher Richard McMahon said.