Black holes are one of the most extreme objects in the universe. It can propel matter outward at near-light speeds in powerful plasma beams known as jets. These jets are thought to be one of the most energetic phenomena in the universe.
Our new work was published today natural astronomychallenges this intuition. It turns out that something as seemingly ordinary as “wind” from a star can rival and even shape the behavior of these powerful jets.
space waltz
The Cygnus X-1 system is like a cosmic waltz between a black hole and a massive star.
A black hole was discovered for the first time in history. It has about 21 times the mass of the Sun and is compressed into an area about 100 kilometers in diameter.
It is what is known as a binary star system with a much larger companion star, almost 40 times the mass of the Sun. Black holes and stars orbit each other every 5.6 days.
For about 20,000 years, the black hole has been feeding on material from the star. This is done by using the star’s strong gravity to capture the star’s powerful stellar wind.
Some of this matter disappears into the black hole, traveling one way across the point of no return (known as the event horizon). A swirling magnetic field is drawn in with the gas, leading to the firing of a jet that moves at nearly the speed of light.
The jet carries energy from near the black hole to a distance of 1 trillion times that amount, or 16 light years away.
Their activity over the past 20,000 years has expanded a giant bubble of hot gas into the surrounding interstellar space. However, despite their importance, measuring the instantaneous power of these jets has remained a major challenge until now.
power couple
Stellar winds are streams of particles that are blown away from the surface of a star by the outward pressure of light. When the solar wind from the Sun is particularly strong, auroras occur when particles collide with Earth’s magnetic field.
Cygnus X-1’s companion star is so massive and so bright that it loses 100 million times the mass of the Sun in its winds and accelerates up to three times faster.
Our study combined telescopes thousands of kilometers apart to create very high-resolution images of the jet. This is the same technique that the Event Horizon Telescope used to create the first images of a black hole.
The winds from Cygnus X-1’s companion star were found to be strong enough to bend the jets fired by the black hole. This shows how powerful the winds of massive stars are.
When a black hole orbits a star, the stellar wind continually pushes on the jet, blowing it away from the star. This causes the wind to change direction, similar to how the wind on Earth blows around the water in a fountain.
From our point of view, the jet appears to be “dancing” with the orbital motion of the system. By modeling this cosmic dance, scientists were able to measure for the first time the jet’s instantaneous power, and found it to be equivalent to 10,000 suns.
Calorie deficit due to black hole diet
Understanding how black holes use their energy can tell us how galaxies evolve.
When matter falls toward a black hole, some of it contributes to the growth of the black hole itself. However, a significant portion can be redirected into jets that inject energy into their surroundings.
In the case of the most massive black holes at the centers of galaxies, the jets can form their host galaxies and influence even larger cosmic structures.
From the X-rays produced by matter falling into the black hole, we can measure how quickly the black hole is feeding. But until now, there was no way to directly measure how much energy goes into these jets at any given moment.
Measurements of Cygnus X-1’s jet output provide a new way to “balance the energy budget” of black holes.
Comparing a black hole’s vegetative velocity and the amount of energy carried away by its jets allows us to fine-tune computer simulations of the universe. This tells us how black holes affect the universe on the largest scale.
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This cosmic dance of black holes and giant stars reveals more than just curved jets. This shows how even the most energetic phenomena, like jets, are shaped by the surrounding environment.
Observing the dancing jets in Cygnus X-1 has deepened our understanding of how black holes influence the evolution of the universe itself.
Steve Prabu, Adjunct Lecturer, School of Electrical Engineering, School of Computing and Mathematical Sciences, Curtin University. Professor James Miller-Jones, Curtin Institute of Radio Astronomy, University of Oxford and Curtin University
This article is republished from The Conversation under a Creative Commons license. Read the original article.
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