New insights Evolution of galaxies

Subject: Science and technology

Section: Space

Context: A study has shown that supermassive black holes may be playing an essential role in the evolution of their host galaxies.

What is a galaxy ?

A galaxy is a sprawling space system which is composed of stars, dust, interstellar gas, stellar remnants, and dark matter and all held together by gravity.
The universe has many galaxies, and each carries millions of stars which are bounded by a unique force known as gravitational force. The solar system where our earth exists is in the Milky Way Galaxy.
Galaxies differ from each other in shape, size, colour and composition. There are three types of galaxies that we find in the universe. i.e. Elliptical Galaxies, Spiral Galaxies and Irregular Galaxies.

New insights in the evolution of galaxy

Supermassive black holes at the centres of galaxies are known to give rise to fast-moving jets of relativistic particles that can traverse large distances through the galaxy and beyond.
The jets have long been suspected of driving the evolution of galaxies.
A new study by an international team of astronomers, including Dipanjan Mukherjee from the Pune-based Inter-University Centre for Astronomy and Astrophysics (IUCAA), has unravelled the mystery.
It has shown that even a relatively weak jet from a supermassive black hole can clear the nuclear region of the galaxy of its gas, indicating that they may be playing an essential role in the evolution of their host galaxies.

What are black holes ?

Black holes are extraordinarily dense objects possessing gravitational pulls so powerful even light cannot escape them.
It refers to a point in space where the matter is so compressed as to create a gravity field from which even light cannot escape.
The black holes belong to two categories:
- One category ranges between a few solar masses and tens of solar masses. These are thought to form when massive stars die.
- The other category is of supermassive black holes. These range from hundreds of thousands to billions of times that of the sun from the Solar system to which Earth belongs.