Black Hole Unmasked: Astronomers Capture First Image of Accretion Ring and Relativistic Jet
Jorge Valasquez
Black holes are some of the most mysterious and fascinating objects in the universe. They are regions of space where gravity is so strong that nothing, not even light, can escape. They are invisible to the naked eye, but they can be detected by their effects on the surrounding matter and radiation.
One of the ways to study black holes is to observe their accretion process, which is the phenomenon of matter falling into the black hole and forming a disk around it. The accretion disk is heated by friction and emits electromagnetic radiation, such as X-rays and radio waves. Another way to study black holes is to observe their jets, which are powerful streams of plasma that are launched from the vicinity of the black hole and travel at near-light speeds across vast distances.
Until recently, however, it was impossible to capture a clear image of both the accretion process and the jet of a black hole at the same time. This is because the resolution and sensitivity of existing telescopes were not sufficient to resolve these features, especially for distant black holes.
But now, thanks to a new technology called Very Long Baseline Interferometry (VLBI), scientists have achieved this remarkable feat for the first time. VLBI is a technique that combines the signals from multiple radio telescopes around the world to create a virtual telescope with a diameter equivalent to the distance between them. This allows for unprecedented angular resolution and sensitivity, enabling astronomers to see details that were previously invisible.
Using VLBI, a team of scientists from various institutions and countries have produced an unprecedented image of both the accretion process and the jet of the Messier 87 (M87) black hole. M87 is a giant elliptical galaxy located about 55 million light-years away from Earth in the Virgo cluster. It hosts one of the most massive known black holes in the universe, with an estimated mass of 6.5 billion times that of the sun.
The image, which was published in the journal Nature on July 12, 2023, shows a bright ring of emission around a dark central region, which corresponds to the black hole's event horizon, or point of no return for matter and light. The ring is composed of hot plasma that is swirling around the black hole at relativistic speeds, meaning close to the speed of light. The image also shows a faint but distinct jet that emerges from the ring and extends for several thousand light-years into intergalactic space. The jet is composed of highly energetic particles that are accelerated by magnetic fields near the black hole.
The image is a remarkable achievement that demonstrates the power and potential of VLBI for studying black holes and other extreme phenomena in the universe. It also provides valuable information about the physics and dynamics of black hole accretion and jet formation, which are still not fully understood. The image also confirms some predictions of general relativity, Einstein's theory of gravity, which governs the behavior of black holes.
The scientists who produced the image are part of an international collaboration called Event Horizon Telescope (EHT), which aims to image the event horizons of supermassive black holes using VLBI. The EHT consists of more than 200 researchers from 13 institutions in 10 countries. The EHT team plans to continue observing M87 and other black holes in different wavelengths and epochs, hoping to reveal more details and insights about these enigmatic cosmic objects.
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