Black hole ‘lying on its side’ challenges current models

(ORDO NEWS) — The researchers found that the axis of rotation of the black hole, which is part of a binary system, is tilted at an angle of more than 40 degrees with respect to the axis of the star’s orbit. These findings challenge current theoretical models for the formation of black holes.

These observations, made by researchers at the Tuorla Observatory in Finland, are the first reliable measurements showing a large difference between the tilts of a black hole’s spin axis and the orbital axis of a binary system. This difference, measured by the authors of the work for the dual system MAXI J1820+070, was more than 40 degrees.

Often the axis of rotation of the central massive body is oriented in the same direction as the axis of rotation of the satellites of this body.

This is done in the case of the solar system – the planets revolve around the sun in one plane, which almost coincides with the equatorial plane of the sun. The inclination of the Sun’s axis of rotation with respect to the axis of the Earth‘s orbit is only 7 degrees.

“In the case of exotic cosmic objects, such as X-ray binaries, including black holes, one should not expect the axes to be aligned. Black holes in such systems were formed as a result of a cosmic cataclysm – the collapse of a massive star.

Now we can see how the black hole is pulling matter from a nearby less massive companion star orbiting it. We see bright optical and X-ray emission, like the “last breath” of material falling into a black hole, as well as radio emission from the relativistic jets emitted by the system,” said Yuri Poutanen, professor of astronomy at the University of Turku, Finland, and the main author of this new publication. .

By tracing these jets, the researchers were able to pinpoint the direction of the black hole’s axis of rotation. As the amount of gas falling from the companion star into the black hole began to decrease, the system’s brightness dropped, and most of the light was now emitted by the companion star.

Under these conditions, the authors were able to measure the inclination of the orbit using spectroscopic methods, and it turned out to be almost co-directional with the ejecta.

“In order to determine the three-dimensional position of the orbit, it is necessary to know the position angle of the system in the sky, that is, how the system is rotated relative to the North in the sky. We were able to measure this angle using polarimetric methods,” said Poutanen.

These results may lead to a revision of modern models of the formation and evolution of binary systems of this type, since the scenarios for the evolution of such systems usually do not allow a large angle b


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