SANTA CRUZ DE TENERIFE, Feb. 25 (EUROPE PRESS) –
A team of researchers led by the University of Turku and in which the Canary Islands Institute of Astrophysics (IAC) participates have discovered a black hole that challenges current theoretical models for the formation of this type of compact object, as it reveals a difference of more than 40 degrees between the axis of the orbit of the X-ray binary called MAXI J1820+070 and the axis of rotation of its black hole.
The existence of a black hole in this binary system was previously confirmed by a team of researchers from the IAC, with observations made at the Gran Telescopio Canarias (GTC or Grantecan) and the William Herschel Telescope (WHT), of the Isaac Newton Group, both installed at the Roque de los Muchachos Observatory in La Palma.
Often, in space systems composed of smaller objects orbiting around the central massive body, this body’s own axis of rotation is aligned with the axis of rotation of its satellites.
This is what happens in the Solar System, where the planets orbit the Sun in a plane that roughly coincides with the equatorial plane of the star, the IAC reports in a note.
The tilt of the Sun’s axis of rotation with respect to the Earth’s orbital axis is just seven degrees.
“The expectation of alignment between celestial bodies, to a large extent, does not hold for objects like black holes found in binary X-ray systems,” says Juri Poutanen, Professor of Astronomy at the University of Turku and lead author. of this article.
COSMIC CAPACISM
In addition, he points out that “the black holes in these systems were formed as a result of a cosmic cataclysm, the collapse of a massive star, and currently, the black hole feeds on gas that comes from its companion star.”
Thus, he continues, “we can observe radiation in the visible and in X-rays emitted by this matter in a last breath, before entering the event horizon, we also observe radio emission from the jet or jet of relativistic particles ejected by the system “.
By following the signal from these jets, the researchers have been able to determine, with great precision, the direction of the black hole’s axis of rotation.
Approximately a year after its identification, with the MAXI instrument installed on the International Space Station, the amount of gas that fell on the black hole began to decrease and with it the system darkened.
Since then, a notable part of the emission has come from the companion star.
From the study of this star with GTC, it was possible to measure the inclination of the orbit by means of spectroscopic techniques and it turned out to practically coincide with the inclination of the jet.
“To establish the spatial orientation of the orbit, it is also necessary to know the angular position of the binary in the plane of the sky”, explains Manuel Pérez Torres, IAC researcher and co-author of this article.
PUBLICATION IN THE MAGAZINE ‘SCIENCE’
Likewise, he adds that “the measurement was obtained by studying a property of the radiation emitted by the binary, its polarization, this information, combined with previous results, has given a detailed image of the architecture of the binary and the 3D orientation of its components, thus leading to the discovery of a black hole that rotates, surprisingly, very tilted with respect to its orbit”.
The results, published today in the journal ‘Science’, open up an interesting perspective on the formation of black holes and the evolution of this type of system, since such an extreme misalignment is difficult to achieve in many hole formation scenarios. blacks and evolution of binary systems.
“The difference of more than 40 degrees between the orbital axis and the spin of the black hole was completely unexpected. Until now, when modeling the behavior of matter in curved temporal space around a black hole, scientists had assumed that this difference was very small. Current models are already really complex, and these new findings force us to add a new dimension to the problem,” says Poutanen.
Prior to the preparation of this work, a team of astrophysicists led by the IAC researcher, Manuel A. Pérez Torres, confirmed the presence of a black hole and obtained the inclination of the orbit with data also obtained from La Palma, with the Great Canary Telescope (GTC or Grantecan) and the William Herschel Telescope (WHT).
However, the key observations for the elaboration of this work were made using the Liverpool Telescope and the DIPol-UF polarimetric instrument, in the Nordic Optical Telescope, which belongs to the Universities of Turku (Finland) and Aarhus (Denmark), both installed on the summit of La Palma
