Discovery of the Largest Stellar Black Hole in our Galaxy through Celestial Wobble

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Recently, astronomers observed the largest stellar black hole ever discovered in the Milky Way galaxy. This discovery was made possible after detecting a peculiar wobble in space.

Gaia BH3, known as the "sleeping giant," is a black hole with a mass almost 33 times that of our sun. It is situated 1,926 light-years away in the Aquila constellation, making it the second-closest black hole to Earth. The closest black hole, Gaia BH1, is approximately 1,500 light-years away and has a mass nearly 10 times that of our sun.

Astronomers stumbled upon Gaia BH3 while analyzing data from the European Space Agency's Gaia space telescope. The unexpected discovery was made while preparing for an upcoming data release to the scientific community. The researchers were surprised by a strange motion caused by Gaia BH3's gravitational pull on a nearby companion.

Many black holes are considered "dormant" because they do not have a companion star nearby to feed on. As a result, these black holes are harder to detect since they do not emit any light. On the other hand, some stellar black holes have a companion star from which they draw material. This process of exchanging matter produces bright X-rays that can be observed using telescopes.

This artist’s impression shows the record-breaking quasar J059-4351, the bright core of a distant galaxy that is powered by a supermassive black hole. Using ESO’s Very Large Telescope (VLT) in Chile, this quasar has been found to be the most luminous object known in the Universe to date. The supermassive black hole, seen here pulling in surrounding matter, has a mass 17 billion times that of the Sun and is growing in mass by the equivalent of another Sun per day, making it the fastest-growing black hole ever known.

This artists impression displays the record-breaking quasar J059-4351, the bright core of a distant galaxy powered by a supermassive black hole. This quasar, observed using ESOs Very Large Telescope (VLT) in Chile, has been identified as the most luminous object in the Universe currently. The supermassive black hole, depicted here attracting surrounding matter, possesses a mass 17 billion times greater than the Sun and is increasing in mass at a rate equivalent to one Sun per day, setting a record as the fastest-growing black hole ever discovered.

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The movement of an old giant star in the Aquila constellation showed that it was in orbit with a dormant black hole. This marks the third dormant black hole discovered by Gaia.

To confirm the mass of Gaia BH3, researchers utilized the European Southern Observatory’s Very Large Telescope in Chile’s Atacama Desert and other ground-based observatories. Their study has provided new insights into the formation of these massive black holes. These findings were published in the journal Astronomy & Astrophysics on Tuesday.

Lead study author Pasquale Panuzzo, an astronomer at the Observatoire de Paris, part of France’s National Centre for Scientific Research, and a Gaia collaboration member, expressed surprise at the unexpected discovery of a high-mass black hole nearby, previously undetected. According to Panuzzo, this type of finding is rare and only occurs once in a researcher's lifetime.

Exploring the mysteries of ancient stars

The title for the most massive black hole in our galaxy will always belong to Sagittarius A*, the supermassive black hole located at the center of the Milky Way, which has about 4 million times the mass of the sun. However, this is because it is a supermassive black hole, not a stellar black hole.

The process by which supermassive black holes form is still not well understood, but one theory suggests it occurs when massive cosmic clouds collapse. On the other hand, stellar black holes are formed when massive stars come to the end of their life cycle. Therefore, Gaia BH3 is the most massive black hole in our galaxy that formed from the death of a massive star.

Stellar black holes found in the Milky Way galaxy are typically 10 times more massive than the sun. Cygnus X-1 was previously the largest known stellar black hole in our galaxy, with a mass of 21 times that of the sun. However, the recent discovery of Gaia BH3 has surpassed Cygnus X-1 in size, making it a remarkable find for astronomers. Despite its significance, Gaia BH3 is comparable in mass to objects observed in faraway galaxies.

Three stellar black holes found in our galaxy, Gaia BH1, Cygnus X-1 and Gaia BH3, have masses that are 10, 21 and 33 times that of the sun, respectively.

Three stellar black holes found in our galaxy, Gaia BH1, Cygnus X-1 and Gaia BH3, have masses that are 10, 21 and 33 times that of the sun, respectively.

M. Kornmesser/ESO

Scientists think that massive black holes like Gaia BH3 were created when stars with few metals collapsed. These stars mainly consist of hydrogen and helium, so they don't lose as much mass during their lives. As a result, they have more material left at the end, which can lead to the formation of a high-mass black hole.

However, astronomers had not been able to find concrete evidence connecting high-mass black holes to metal-poor stars until the discovery of Gaia BH3.

The study authors noted that paired stars often have similar compositions. In line with this idea, the researchers discovered that the star orbiting Gaia BH3 had low metal content, suggesting that the star responsible for creating Gaia BH3 was likely the same.

One of the study coauthors, Elisabetta Caffau, a member of the Gaia collaboration at the Observatoire de Paris, commented, "What stands out to me is that the chemical makeup of the companion closely resembles that of old metal-poor stars found in our galaxy."

This is the first image of Sgr A*, the supermassive black hole at the center of our galaxy, with a black background added to fit wider screens. It's the first direct visual evidence of the presence of this black hole.

The image was captured by the Event Horizon Telescope (EHT), which is an array that connected eight radio observatories around the world to create a single "Earth-sized" virtual telescope. The telescope is named after the event horizon, which is the boundary of the black hole where no light can escape. Although we can't see the event horizon itself because it doesn't emit light, we can see glowing gas orbiting around the black hole, revealing a dark central region (shadow) surrounded by a bright ring-like structure.

The new view shows light bent by the strong gravity of the black hole, which is four million times more massive than our Sun. The image of the Sgr A* black hole is an average of different images extracted from the 2017 observations of the EHT Collaboration. In addition to other facilities, the EHT network of radio observatories that made this image possible includes the Atacama Large Millimeter/submillimeter Array (ALMA) and the Atacama Pathfinder EXperiment (APEX) in the Atacama Desert in Chile, which are co-owned and operated by ESO as a partner on behalf of its member states in Europe.

European Southern Observatory/EHT Collaboration

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Scientists have discovered that our galaxy's black hole spins rapidly and pulls space-time along with it. This phenomenon has been observed with the star orbiting Gaia BH3, which is believed to have formed within the first 2 billion years after the universe was created in the big bang 13.8 billion years ago. The star's unique trajectory, moving in the opposite direction of many stars in the Milky Way's galactic disk, indicates that it was once part of a small galaxy that merged with our Milky Way over 8 billion years ago.

The team is hopeful that their research will enable other astronomers to study the massive black hole and uncover more of its mysteries without having to wait for the rest of the Gaia data release, scheduled for late 2025.

Carole Mundell, the European Space Agency's director of science, expressed her awe at the transformative impact Gaia is having on the fields of astronomy and astrophysics. She stated that the discoveries made by Gaia are exceeding the original mission goal of creating a highly accurate map of over a billion stars in the Milky Way galaxy.

Editor's P/S:

The discovery of Gaia BH3, the largest stellar black hole in the Milky Way, has captured the attention of astronomers worldwide. This remarkable finding sheds light on the formation and evolution of these enigmatic objects. The detection of Gaia BH3 was made possible through the analysis of data from the European Space Agency's Gaia space telescope, which has provided unprecedented insights into the structure and dynamics of our galaxy.

The study of Gaia BH3 and other stellar black holes holds immense significance for astrophysics. By exploring the properties and behavior of these objects, astronomers can gain valuable clues about the formation of galaxies, the evolution of stars, and the nature of gravity itself. The discovery of Gaia BH3 serves as a testament to the power of scientific collaboration and the continuous advancement of our understanding of the universe.