Astronomers discover that a well-known X-ray phenomenon is a hidden X-ray source.

Astronomers have discovered that the well-known X-ray pair, whose origin has been a mystery to scientists until now, is actually a hidden X-ray source. The study is published in Natural Astronomy.

X-ray binaries are interesting systems consisting of two celestial bodies: a normal star and a compact, dead object such as a black hole or neutron star absorbing material from its stellar companion. A few hundred such sources have been identified so far in our galaxy. When it comes to the most powerful events in the universe, the release of gravitational energy in X-ray binaries is seen as a very efficient process.

Among the first X-ray binary systems discovered in the universe was the Cygnus X-3 system. Since the early 1970s, this binary system has been known for its ability to briefly emerge as one of the strongest radio sources, but within days it fades or disappears altogether. This unique characteristic inspired early efforts, coordinated by telephone, to connect astronomical observations around the world.

The unique behavior of the system during these short-lived, high-energy events, in contrast to its “normal” nature, led to it being called the “astronomical mystery Cygnus X-3” by RM Hjellming in 1973. Many efforts have focused on understanding its nature since at that time.

Success in solving this mystery has been achieved by the study of this system using the Imaging X-ray Polarimetry Explorer (IXPE) satellite that was launched by NASA in December 2021. According to Alexandra Veledina, Associate Researcher at the University of Turku in Finland and the author head of the study, the use of X-ray vision has provided insight into the configuration of matter orbiting a compact object in close proximity to a black hole.

“We discovered that the compact object is surrounded by an envelope of dense, opaque matter. The light we see is reflected from the inner walls of the funnel formed by the swirling gas, resembling a cup with a mirror inside,” Veledina explains. .

This revelation has led to the identification of Cygnus X-3 as a member of the class of ultra-luminous X-ray sources (ULXs), which consume matter at such an incredible rate that most of the infalling material does not enter. event horizon, but is instead deleted by the system.

“ULXs are usually observed as bright spots in images of distant galaxies, and their emission is amplified by the focusing effect of the funnel of the surrounding object, which works like a megaphone,” explains Juri Poutanen, Professor at the Department of Physics and Astronomy. University of Turku and co-author of the study.

“However, due to the great distance of these sources, thousands of times the length of the Milky Way, they appear weak to X-ray telescopes. Our discovery has now revealed a bright counterpart to these distant ULXs that reside within our own galaxy. .”

Researchers believe this important discovery marks a new chapter in the study of this mysterious cosmic source, offering the opportunity for a detailed study of the use of extreme substances.