The mechanism underlying the phenomenon that makes some black holes super-luminous, hitherto unknown, has been revealed: the extremely energetic particles produced by these cosmic objects are accelerated by shock waves, and this allows them to generate light.
The discovery is due to the Ixpe space observatory (Imaging X-ray Polarimetry Explorer), built by the Italian Space Agency (ASI) and NASA and launched in December 2021, which finally made it possible to observe black holes in x-rays and therefore answer the question .
The result was published in the journal Nature by an international group of researchers led by the Finnish University of Turku, with the important Italian contribution of Asi, the National Institute of Astrophysics (Inaf), the National Institute of Nuclear Physics (Infn) and the Universities of Siena and Turin.
The researchers, led by Ioannis Liodakis, used Ixpe to observe the blazar Markarian 501. Blazars are galaxies that host a supermassive black hole at their centre, which releases powerful jets of matter pointing in the direction of the Earth: these are highly energy, which give rise to the most violent phenomena in the universe.
Most of the blazars' light is produced by high-energy particles, but how these particles become so energetic has so far remained an unanswered question.
The authors of the study have now been able to compare the data obtained in radio and optical frequencies with those in x-rays produced by Ixpe, which measured the particle jets and discovered that the initial acceleration is due to shock waves that propagate from from the black hole.
“This is a huge leap forward,” comments Lea Marcotulli of the American University of Yale, in a companion article to the study also published in Nature, “And it brings us one step closer to understanding these extreme cosmic objects , whose nature has been the focus of much research since their discovery.
