Nature World News writes that three super massive black holes which were orbiting closely have been discovered. They are 4 billion light years away from the Earth.

According to the theory of General Relativity, groups of black holes like this one are thought to be the source of gravitational waves in the Universe.

"Using the combined signals from radio telescopes on four continents we are able to observe this exotic system one third of the way across the Universe", said research leader Robert Deane.

The detailed study of the discovery is published in Nature journal.

This is the tightest group of black holes which has ever been known and is quite remarkable since most of the galaxies have just one black hole at their centre. The discovery suggests that closely packed super massive black holes like these are quite common than thought earlier.

It is believed that galaxies evolve through merging and that leads to multiple super massive black holes in some of the galaxies at a given time.

Very little is actually known about systems of black hole, which are so close to one another that they emit gravitational waves that are detectable. According to the study, two of the inner black holes of the triple system are emitting massive jet streams of radiation and gas.

Such jet streams are a known feature of massive black holes which are located in the centre of a galaxy.

The resulting helical stream, which is formed from the orbiting streams was picked up by a Very Long Baseline Interferometry (VLBI) technique that combines the signals from large radio antennas, are up to 10,000 kilometres apart, says the Nature World News.

The VLBI technique is able to witness deep space details 50 times clearer than the Hubble Space Telescope.

"VLBI is widely recognized as one of the best ways to confirm close-pair black hole systems but the main difficulty has always been pre-selecting the most promising candidates", co-author Zsolt Paragi from the Joint Institute for VLBI said in a statement.