OJ 287

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OJ 287 is a quasar in the constellation Cancer , 3.5 billion light years away , that contains one of the largest known black holes with 18 billion solar masses . The observation of OJ 287 is the first direct evidence that black holes of this size can exist in quasars.

Determination of mass in the double system

The object also contains another black hole with 100 million solar masses and is therefore a double system. The smaller black hole orbits the larger one once every twelve years. With each orbit, it penetrates the accretion disk of the more massive partner twice , which is accompanied by gas eruptions that cause visible changes in brightness.

Due to their proximity to each other, after about a dozen observed eruptions, astronomers were able to determine the mass of the black holes. Although black holes of similar size are known, the mass has not yet been determined with such accuracy in any other case.

Detection of gravitational waves

Since an arrangement with such extreme gravitational fields is very rarely observed in the universe, OJ 287 also proves to be a good study subject for general relativity . By applying the relativistic theory of gravity , the point in time of the eruptions could be predicted with a high degree of accuracy (apart from slight deviations caused by disturbance variables such as insufficient data). This indirectly confirms Einstein's theory of the radiation of gravitational waves .

The research group, led by the Finnish scientist Mauri Valtonen from the University of Turku, published its sensational results in the science magazine Nature in April 2008 , after their predictions for the observed outbreak on September 13, 2007 had been confirmed almost exactly. The last outbreak began in late 2015, in line with predictions.

The indirect proof clearly surpasses the phenomena of this type that were previously observed in other parts of the universe. Due to the decrease in orbital energy at OJ 287, a relativistic rotation of the orbital ellipse ( periastron rotation) of 39 ° per revolution was measured, while this effect was only 4.2 ° per 1150 with the double pulsar PSR 1913 + 16 previously used for indirect detection Rounds (one year). Since the orbit of the double object is steadily decreasing as a result of this decrease, the two black holes will, according to calculations, unite in about 10,000 years.

This makes the OJ 287 a suitable target object for direct measurement of gravitational waves with the planned LISA space interferometer .

Web links

Individual evidence

  1. ↑ MJ Valtonen et al. : A massive binary black-hole system in OJ 287 and a test of general relativity . In: Nature. No. 452, 2008, pp. 851-853.
  2. ↑ A quasar confirms the relativity theory Spektrum.de, December 30, 2015, accessed on February 20, 2016 (German)