For decades, cosmologists have puzzled about the nature of the enigmatic dark energy that is fueling the universe's expansion. The answer may now be found in supermassive black holes.
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| Sources of dark energy |
The massive black holes located at the cores of most big galaxies are potential dark energy sources. This result was reached by analyzing supermassive black holes spanning nine billion years of cosmic history. The results were reported in the Astrophysical Journal in the Astrophysical Journal Letters.
"If the theory is correct, it will revolutionize all of cosmology because we finally have a solution to the origin of dark energy, which has puzzled cosmologists and theoretical physicists for more than 20 years," said co-author Chris Pearson, an astrophysicist at the UK's Rutherford Appleton Laboratory (RAL).
Astronomers only recently discovered that the cosmos is expanding at an increasing rate. This was startling because gravity was supposed to be gradually compressing the universe under its own strength in a process known as the Great Crunch. To explain this disparity, physicists proposed that there must be something powerful enough to counterbalance gravity, which is pulling everything in the universe away. This was referred to as dark energy. And this is no little matter, as energy accounts for around 68 percent of the total universe.
New research appears to have discovered a hint as to how the concealed phenomena operates. The masses of black holes at the cores of two groupings of galaxies were compared by two teams of researchers. One group was youthful and far away, with light reaching us nine billion years ago, while another was closer and older, only a few million light-years away. The scientists discovered that the black holes that were closest to them had grown seven to twenty times bigger than those in the comparison group. There is a tremendous increase that cannot be explained merely by black holes eating stars or colliding and linking.
Instead, the researchers believe that the black holes are expanding in lockstep with the rest of the universe. "This is a really unexpected outcome. We began by studying how black holes evolve over time and may have discovered the solution to one of cosmology's most difficult challenges "says co-author and Imperial College London astronomer Dave Clements.