A binary system containing a massive star and what is probably a black hole, which together are a source of intense X-rays, has been shown to be a smaller-scale example of some of the brightest quasars in the UNIVERSE.
The new findings, from an international team that used NASAS ‘ Imaging X-ray Polarimetry Explorer spacecraft (IXPE), describe how an X-ray binary system located about 24,000 light years away in ours The Milky Way Galaxy is amplifying its X-ray emission in a funnel-shaped cavity surrounding the possible black hole.
The system, Cygnus X-3, was discovered in the early 1970s when radio telescopes spotted powerful jets radiating from it at nearly the speed of light. The radio emission from these aircraft lasts for a few days before turning off, only to come back on later.
The origins of the planes were, at the time, mysterious. The system was described as an “astronomical puzzle”, not helped by the fact that we can’t even see Cygnus X-3 in visible light; it is blocked by thick dust in the plane of our galaxy. During the 1970s, radio astronomers at observatories around the world coordinated by telephone to try to catch Cygnus X-3 in the act of turning on or off.
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Over the years, further observations at radio, infrared and X-ray wavelengths allowed astronomers to realize that Cygnus X-3 is an X-ray binary system involving the transfer of matter between a massive star and an object compact orbiting a common center. e gravity. Compact object is either a neutron star or, more likely, a black hole with a mass about five times that mass of our sun. The massive star is a Wolf-Rayet star – a rare phase that supergiant stars undergo, where they emit powerful stellar winds that begin to lift large portions of their outer envelope into ROOM. It is material blown up by this Wolf-Rayet star that feeds an accretion disk orbiting the compact object.
However, the Cygnus X-3 LIGHTENING hardly believable. The flow of matter in a compact object like a black hole is controlled by a property known as the Eddington Limit. If the accretion rate is high enough, the accretion disk becomes a jam – matter ends up accreting, the disk becomes dense and so hot that the amount of radiation that flows out can stop fresh material from entering. In this way, black holes can regulate their growth and some of the material is spit out in the radio-emitting jets.
However, some of the brightest the quasars — the most active galaxy supermassive black holes at their cores—appear to break the Eddington limit, in that their luminosity is extremely high, but they still appear to be accreting matter. And Cygnus X-3 seems to fall into this category, albeit to a lesser degree.
Now, a team led by Alexandra Veledina from the University of Turku in Finland has used IXPE to measure the degree of polarization in the X-ray light coming from Cygnus X-3. They found that the amount of polarization is high enough that it can only be explained by X-rays scattering from the interior of a funnel-shaped cavity at the heart of the accretion disk.
“We have discovered that the compact object is surrounded by an envelope of dense, dark matter,” Veledina said in a STATEMENT. “The light we observe is a reflection from the inner walls of the funnel formed by the surrounding gas, which resembles a cup with an internal mirror.”
A dark envelope rising from a funnel-shaped cavity is typical of quasars described as ‘ULXs’ – ultra bright X-ray sources. The degree of amplification as a result of X-ray scattering inside the funnel cavity is also analogous to ULXs.
“ULXs are typically seen as bright spots in images of distant galaxies, with their emissions amplified by the funnel focusing effects of the compact object around, acting like a megaphone,” said study team member Juri Poutanen from University of Turku. “However, because of the great distances from these sources … they appear relatively faint to X-ray telescopes.”
Therefore, learning about ULXs in quasars has proven difficult, but astronomers can now use the much closer Cygnus X-3 as a model to better understand those distant ULXs.
“Our discovery has now revealed a bright counterpart to these distant ULXs that reside within our galaxy,” said Poutanen.
Cygnus X-3’s explosions are interrupted thanks to the Wolf-Rayet star’s elliptical orbit around the compact object, meaning it is sometimes closer and more material in the wind falls onto the potential black hole. IXPE was able to see that when Cygnus X-3 is in its ULX phase—when the amount of infalling material is at its maximum—the polarization rate reaches 24.9%, but when the system is less active, the polarization drops to 10.4%. . This suggests that the structure of the funnel changes in response to larger or smaller amounts of addition. If the accretion rate drops too low, the funnel may collapse completely, only to rebuild itself when the accretion picks up again, Veledina’s team predicts.
The team is now planning further observations to try to catch this collapse happening, which would be signaled by the polarization dropping to near zero, indicating that the X-ray emission comes directly from hot gas on the surface of the accretion disk and not indirectly. via in-funnel delivery.
The findings were published June 21 in the journal Astronomy of Nature.