An international team of astronomers has made groundbreaking progress in the study of a long-known but mysterious X-ray binary system. According to research published in the journal Nature Astronomy, the object known as Cygnus

X-ray binaries, consisting of an ordinary star and a compact object (a black hole or neutron star), are among the most energetically powerful phenomena in the universe. Hundreds of such systems have been discovered in our galaxy, which are distinguished by a highly efficient process of releasing gravitational energy.

Discovered in the early 1970s, the Swan X-3 system long puzzled scientists because of its unusual behavior. It periodically became one of the most intense radio sources in space, but after a few days it faded away or disappeared completely. This phenomenon, dubbed the “astronomical mystery of Cygnus X-3” by Robert Hjellming (RM Hjellming) in 1973, spurred the first international efforts to coordinate astronomical observations.

The key to solving this mystery was found thanks to the Imaging X-ray Polarimetry Explorer (IXPE) satellite that NASA launched in December 2021. The lead author of the study, Dr. D., from the University of Turku (Finland). Alexandra Veledina explains: “Using X-ray polarized ‘vision’ allowed us to better understand the configuration of the matter around the compact object. We found that it is surrounded by a dense shell of matter. The light we observe comes from the inner walls of a funnel formed by the surrounding gas, resembling a mirrored bowl.” It is an incoming reflection.”

This discovery led to the identification of Cygnus X-3 as a member of the class of ultraluminous X-ray sources. These objects absorb matter at such a speed that a significant part of it does not enter the event horizon, but is expelled from the system.

Professor Juri Poutanen, co-author of the study, adds: “ULXs are usually seen as bright dots in galaxy images. Their radiation is amplified due to the focusing effect of the funnel surrounding the compact object, acting like a megaphone. However, due to their large distance, which is thousands of times larger than the size of the Milky Way, they appear relatively faint to X-ray telescopes. Our discovery has revealed a bright counterpart to these distant ULXs in our own galaxy.”

This discovery opens a new page in the study of extreme cosmic events and provides an opportunity for a more in-depth study of the processes of absorption of matter by supermassive objects. Further studies of Cygnus X-3 are expected to help scientists better understand the nature of ULXs and their role in galaxy evolution.