Why is it in the News?

For the first time, astronomers have observed the area right at the edge of a black hole where matter stops orbiting and plunges straight in at near-light speed.

What is the Plunging Region of a Black Hole?

• The plunging region of a black hole is an area where matter ceases to orbit the celestial object and instead falls directly into its incalculable depths.
  • This phenomenon was initially predicted by Albert Einstein's groundbreaking theory of general relativity, which continues to shape our understanding of the cosmos.
• As matter approaches a black hole, it is torn apart and forms a rotating ring known as an accretion disc.
• According to general relativity, there exists an inner boundary within this disc, beyond which nothing can maintain its orbit around the black hole.
  • Instead, the material is drawn towards the black hole at nearly the speed of light, marking the beginning of the plunging region.
• This region, situated just outside the event horizon, represents the point of no return for matter falling into a black hole.
• Despite the challenges posed by studying these enigmatic structures, researchers believe that investigating plunging regions could unveil new insights into the formation and evolution of black holes.
• Additionally, these studies may offer valuable information about the fundamental properties of space-time, potentially transforming our understanding of the universe and its most mysterious inhabitants.

What is a Black Hole?

• A black hole is a celestial phenomenon that arises from the remnants of a massive star that has exhausted its nuclear fuel and undergone gravitational collapse.
• It is characterized by an unfathomably dense core, known as a singularity, which is enveloped by a boundary called the event horizon.
• The event horizon serves as a point of no return; any matter or light that crosses this boundary is irrevocably drawn towards the singularity, making it impossible to escape the immense gravitational pull.

Black holes are classified into three categories based on their size and formation process:

• Stellar-mass black holes: These form when a massive star collapses at the end of its life cycle. They typically have masses ranging from approximately five to several dozen times that of our Sun.
• Supermassive black holes: Found at the centre of most galaxies, including our own Milky Way, these colossal structures boast masses that can reach billions of times the mass of the Sun.
• Intermediate-mass black holes: With masses between those of stellar mass and supermassive black holes, these entities are thought to form through the merger of smaller black holes or the collapse of dense clusters of stars.
• Due to their extreme nature, black holes have been the subject of extensive research and fascination in the scientific community.
• The study of these enigmatic structures continues to yield invaluable insights into the fundamental principles governing our universe.

Why is it in the News?

European astronomers have made a groundbreaking discovery by identifying Gaia-BH3, a colossal black hole located just 2,000 light years away from Earth within the Milky Way, revolutionizing our comprehension of star formation.

What Is Gaia-BH3?

• Gaia-BH3, a stellar black hole in the Milky Way galaxy, has been identified as the most massive one discovered to date.
• The European Space Agency's Gaia mission detected Gaia-BH3 due to its distinctive 'wobbling' effect on a companion star orbiting it.
• Through the use of the Very Large Telescope at the European Southern Observatory in Chile's Atacama Desert and other ground-based observatories, researchers confirmed its enormous mass.
• With a mass 33 times greater than our sun, Gaia-BH3 is situated in the Aquila constellation at a distance of 1,926 light-years from Earth, earning it the title of the second-closest known black hole.
• Gaia BH1, located about 1,500 light-years away, remains the closest known black hole to Earth with a mass approximately 10 times that of our sun.
• While Gaia-BH3 holds the distinction of being the most massive stellar black hole in our galaxy, it pales in comparison to Sagittarius A*, the supermassive black hole at the Milky Way's center, which boasts a staggering mass of roughly 4 million times that of the sun.

Difference Between Stellar and Supermassive Black Holes:

• Stellar and supermassive black holes are two distinct types of cosmic phenomena, each with unique characteristics and origins.
• Stellar-mass black holes result from the gravitational collapse of a single star or the merger of two neutron stars, resulting in masses comparable to stars.
  • Their mass typically ranges from three to fifty times that of our sun.
• In contrast, supermassive black holes boast a mass exceeding 50,000 times the solar mass, often reaching into the millions or billions.
  • The formation of supermassive black holes remains a mystery to scientists, as they are too massive to have formed from a single star's collapse.
• Their consistent presence at the center of galaxies suggests a potential connection to galactic formation.
• While our understanding of these cosmic giants continues to evolve, one thing is clear: both stellar and supermassive black holes are awe-inspiring fixtures in our universe.