Cambridge researchers have discovered a new population of enormous, rapidly growing supermassive black holes in the early Universe.
The most extreme object in the research, accepted for publication in the journal Monthly Notices of the Royal Astronomical Society (arXiv.org version), is a supermassive black hole called ULASJ1234+0907.
This object, located in the direction of the constellation of Virgo, is so far away that the light from it has taken 11 billion years to reach us, so we see it as it appeared in the early Universe. The monster black hole has 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.
The study indicates that that there may be as many as 400 such giant black holes in the part of the Universe that we can observe. These black holes were previously undetected because they sit cocooned within thick layers of dust. The study has shown however that they are emitting vast amounts of radiation through violent interactions with their host galaxies.
“These results could have a significant impact on studies of supermassive black holes” said Dr Manda Banerji of the University of Cambridge’s Institute of Astronomy, lead author of the study. “Most black holes of this kind are seen through the matter they drag in. As the neighboring material spirals in towards the black holes, it heats up. Astronomers are able to see this radiation and observe these systems. Although these 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.”
The newly discovered black holes, devouring the equivalent of several hundred Suns every year, will shed light on the physical processes governing the growth of all supermassive black holes.
Supermassive black holes are now known to reside at the centers of all galaxies. In the most massive galaxies in the Universe, they are predicted to grow through violent collisions with other galaxies, which trigger the formation of stars and provides food for the black holes to devour. These violent collisions also produce dust within the galaxies therefore embedding the black hole in a dusty envelope for a short period of time as it is being fed.
In comparison with remote objects like ULASJ1234+0907, the most spectacular example of a dusty, growing black hole in the local Universe is the well-studied galaxy Markarian 231 located some 600 million light years away. Detailed studies with the Hubble Space Telescope have shown evidence that Markarian 231 underwent a violent impact with another galaxy in the recent past.
ULASJ1234+0907 is a more extreme version of this nearby galaxy, indicating that conditions in the early Universe were much more turbulent and inhospitable than they are today.
Bibliographic information: Banerji M. et al. 2012. Heavily Reddened Quasars at z~2 in the UKIDSS Large Area Survey: A Transitional Phase in AGN Evolution. Accepted for publication in MNRAS; arXiv: 1203.5530