A Black hole at the centre of the Milky Way Galaxy

Syllabus: General Studies Paper 3

Scientists from the Event Horizon Telescope (EHT) facility, revealed the first image of the black hole at the centre of the Milky Way.

• Astronomers believe nearly all galaxies, including our own, have these giant black holes at their centre
• The Milky Way black hole is called Sagittarius A*, near the border of Sagittarius and Scorpius constellations.
• It is 4 million times more massive than our sun.
• The image of Sagittarius A* (SgrA*) gave further support to the idea that the compact object at the centre of our galaxy is indeed a black hole, strengthening Einstein’s general theory of relativity.

What is Black Hole?

• Black hole refers to a point in space where matter is so compressed as to create a gravity field from which even light cannot escape.
• Light gets chaotically bent and twisted around by gravity as it gets sucked into the abyss along with superheated gas and dust.
• Black-holes were theorized by Albert Einstein in 1915.

A black hole has two parts:

• Singularity at its core– a point that is infinitely dense, as all the remnant mass of the star is compressed into this point.
• Event Horizon – There is a region of space beyond the black hole called the event horizon. This is a “point of no return”, beyond which it is impossible to escape the gravitational effects of the black hole.

Event Horizon Telescope Project

• EHT is a group of 8 radio telescopes located in different parts of the world.
• In 2006, an international team of more than 200 researchers, led by Harvard University astronomers, launched the Event Horizon Telescope (EHT) project with a sole aim: to capture a direct shot of a black hole.

General Theory of Relativity

• Essentially, it’s a theory of gravity. The basic idea is that instead of being an invisible force that attracts objects to one another, gravity is a curving or warping of space. The more massive an object, the more it warps the space around it