The Department of Science and Technology recently reported an exciting discovery: a rare triple Active Galactic Nucleus (AGN) formed by the merger of three supermassive black holes from different galaxies. This groundbreaking discovery sheds light on some key aspects of the universe and has potential implications for our understanding of black holes, galaxy collisions, and AGNs.
Unraveling the Triple AGN Discovery
Indian scientists were studying AGNs in two massive barred spiral galaxies – NGC7733 and NGC7734, when they noticed peculiar emissions from the center of NGC7734 and an unusual movement within a large bright clump in it. This clump had a different velocity than NGC7733, leading to the identification of a third separate galaxy named NGC7733N.
These three merging black holes were part of galaxies located within the Toucan constellation. Prior to this discovery, several AGN pairs had been detected using X-ray observations, but instances of triple AGN are exceptionally rare, marking this discovery as truly significant.
About the Toucan Constellation
The Toucan constellation is situated in the southern hemisphere of the sky. Visible at latitudes south of 15 degrees between August and October, it remains completely below the horizon for anyone north of 30 degrees. Although small in size, covering just 295 square degrees, the Toucan constellation ranks 48th in size among the 88 constellations in the night sky.
Understanding Active Galactic Nuclei
In the heart of galaxies are supermassive black holes known as AGN. These black holes are several million solar masses in size, and continually accumulate gas, dust, and stellar debris around them due to their immense gravitational pull.
The gravitational energy of these materials is converted into light when they’re pulled towards the black hole, forming the AGN. The AGN often has a glow around it as it accretes matter, making its presence evident through light spectroscopy.
The Intricacies of Galaxy Collisions
When two galaxies collide, their black holes also draw closer, transferring kinetic energy to the surrounding gas. Over time, the distance between the black holes decreases until they are separated by a parsec (3.26 light-years). Beyond this point, they can’t lose any more kinetic energy to approach each other further. This predicament is known as the final parsec problem.
Implications of the New Discovery
The presence of a third black hole could potentially solve the final parsec problem. It signifies that it’s possible for two galaxies to move closer when another black hole or star passes by and absorbs some of their combined angular momentum. According to the findings, multiple accreting black holes or AGNs may be more prevalent in our universe, particularly in galaxy groups. Their growth may be primarily driven by such mergers.
The Anatomy of a Black Hole
A black hole is a region in space where matter is so densely packed that it creates a gravitational field so strong that even light cannot escape. This powerful concept was theorized by Albert Einstein in 1915 and the term ‘black hole’ was first introduced in the mid-1960s by American physicist John Archibald Wheeler.
Black holes generally fall into two categories: smaller ones form when massive stars die and range between a few solar masses and tens of solar masses; while supermassive black holes range from hundreds of thousands to billions of times that of the sun. When two black holes orbit each other and merge, they create gravitational waves. In 2019, scientists from the Event Horizon Telescope Project even captured the first-ever image of a black hole’s shadow.
Last Modified: February 13, 2024