black hole

black hole

black hole

Reactions: evidence found of a cosmic background of gravitational waves possibly produced by supermassive black hole collisions

The International Pulsar Timing Array (IPTA) consortium has discovered evidence for the existence of a cosmic background of gravitational waves. The results, published by different IPTA consortia in several scientific journals, would show that this cosmic background would be the result of collisions of supermassive black holes. In 2015, researchers from the LIGO and Virgo collaborations made the first direct observation of gravitational waves caused by the collision of two stellar-mass black holes. These waves oscillate several times per second. What the consortia have now found are gravitational waves emitted by supermassive binary black holes at the centre of galaxies, waves that oscillate on timescales of many years.

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What we have learned from the first image of Sagittarius A*

The first direct image of the black hole at the centre of our galaxy shows a 'monster' devouring matter at a slow pace. The black hole itself is spinning, and its spin axis is pointing just 30 degrees away from us. The result shows that the size of the black hole is proportional to the mass it contains, confirming the theory of general relativity. Xavier Barcons, ESO's Director General, assesses the new finding.

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