The largest black hole in the Milky Way has been detected looking directly towards Earth.
Did you know that our galaxy, the Milky Way, hides a mysterious sleeping giant near Earth? That giant is none other than a massive black hole recently discovered by the European Gaia space telescope . This discovery represents a milestone in astronomy, since it is the first time that such a massive stellar mass black hole has been found so close to our planet.
Gaia-BH3: A True Cosmic Unicorn
The black hole in question, named Gaia-BH3, is a
true cosmic unicorn. With a mass 33 times that of the Sun, this colossus is the
most massive stellar-mass black hole found in our galaxy to date. The previous
record was held by a black hole in an X-ray binary in the constellation Cygnus
(Cyg X-1), with a mass about 20 times that of the Sun.
A Close Neighbor
But what is really surprising about Gaia-BH3 is its
proximity to Earth. It is located just 2,000 light years away , making it the
second closest black hole to our planet ever discovered. The closest is
Gaia-BH1, also discovered by Gaia, which is 1,560 light years from Earth, but
with a mass of only 9.6 times that of the Sun, making it considerably smaller
than Gaia-BH3.
An Exceptional Discovery
George Seabrook, a scientist at University College London's Mullard Space Science Laboratory and a member of Gaia's Black Hole Task Force, compared the discovery of Gaia-BH3 to the moment in the movie "The Matrix" where Neo begins to "see" the matrix. According to Seabrook, "in our case, 'the matrix' is the population of dormant stellar black holes in our galaxy, which were hidden from us before Gaia detected them."
The Origin of Stellar Mass Black Holes
Stellar-mass black holes form when a large star runs out of fuel and collapses under its own gravity. These compact, extremely dense objects are surrounded by an event horizon, a limit beyond which nothing, not even light, can escape their relentless gravitational pull.
A Challenge to Detect Latent Black Holes
One of the biggest challenges in astronomy is
detecting black holes that are not feeding on surrounding material, such as gas
and dust. In these cases, black holes do not emit or reflect light, so they are
practically invisible to conventional telescopes.
The Key Is in the Movement
Gaia's trick in detecting Gaia-BH3 was to observe the motion of its companion star. When a star orbits the center of mass of a binary system that includes a black hole, its motion exhibits a characteristic wobble. Gaia, with its ability to accurately measure the motion of stars, was able to detect this wobble in Gaia-BH3's companion star.
A Finding That Defies Theories
In addition to its exceptional mass and closeness,
Gaia-BH3 presents another intriguing feature. Its companion star is a
“metal-poor” subgiant, meaning it lacks elements heavier than hydrogen and
helium. This suggests that the star that collapsed to form Gaia-BH3 also lacked
such elements.
Traditionally, it was believed that metal-poor stars could not maintain enough mass to generate black holes. However, Gaia-BH3 challenges this theory and opens new questions about the formation of stellar-mass black holes.
A Window into the Matrix
According to Seabroke, "Gaia's next data release is expected to contain many more black holes, which should help us 'see' more of 'the matrix' and understand how dormant stellar black holes form." This discovery is just the beginning of a new era in the study of these fascinating cosmic objects.
Conclusion
The discovery of Gaia-BH3 not only surprises us with
a massive, close cosmic neighbor, but also challenges our understanding of the
formation of stellar-mass black holes. This sleeping giant near Earth promises
to reveal more secrets about the nature of these enigmatic objects and open new
doors in our exploration of the cosmos.
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