OJ 287 is a 3.5 billion light-years distant quasar in the constellation Cancer, which contains the second- largest known black hole 18 billion solar masses. The observation of OJ 287 is the first direct evidence that black holes of this size may exist in quasars.
Mass determination in double system
The object was another black hole of 100 million solar masses, making it a double system. The smaller black hole orbits the larger one in twelve years. In every round, it penetrates twice the accretion disk of the more massive partner, which is accompanied by gas eruptions that cause visible changes in brightness.
Due to the proximity to each other it was possible to astronomers after about a dozen of observed eruptions, determine the mass of the black holes. Although similar-sized black holes are known, the mass could be determined yet in no other case with such accuracy.
Detection of gravitational waves
Since an arrangement with such extreme gravitational fields is very rare to see in our universe, itself proves OJ 287 as a good object of study for the General Theory of Relativity. By applying the relativistic theory of gravitation namely the timing of eruptions could be predicted with high accuracy (up to slight variations due to disturbances such as an insufficient data base). This indirectly confirms Einstein's theory of emission of gravitational waves.
The researchers published under the direction of the Finnish scientist Mauri Valtonen of the University of Turku their sensational results in April 2008 in the scientific journal Nature, after their forecasts at the last observed eruption on 13 September 2007 had almost exactly confirmed. The next outbreak will be monitored according to the model developed by Valtonen model in 2016.
The indirect evidence surpasses the earlier elsewhere in the universe already observed phenomena of this kind clearly meaningful. Thus a relativistic rotation of the orbital ellipse ( periastron rotation) was measured from 39 ° per orbit due to the decrease of the orbital energy in OJ 287, while this effect in the double pulsar previously used for the indirect detection PSR 1913 16 only 4.2 ° per 1150 rounds amounts (one year). Since the orbit of the double object continuously reduced by this decrease, the two black holes will unite According to the calculations in about 10,000 years.
For OJ 287 is according to the researchers, a suitable target for the expected direct detection of gravitational waves. For this purpose, the detector LISA was intended, which was to be installed in space originally, which was abandoned for cost reasons in 2011.