The “heart” of our galaxy – Black hole’s revelation

A black hole, is a cosmic body of extremely intense gravity from which nothing, not even light, can escape.

Sagittarius A*

Our galaxy’s humongous black hole that is “located” at its center, has been captured by asronomers.

Sagittarius A* sits at the the center of our Milky Way galaxy, in the direction of the Sagittarius constellation. For decades, astronomers have been measuring blasts of radio waves from an extremely compact source there.

The size of a black hole is defined by its event horizon.

In other words, this is the distance from the center of the black hole within which nothing can escape.

Sagittarius A* has a diameter of 16 million miles (26 million kilometers).

26,000 light-years away, Sagittarius A* is four million times the mass of our sun and 40 million miles (60 million kilometers) across.

In general the same “rules” for black holes apply in this particular case as well.

They are massive physical objects that are difficult to observe directly but quite easy to characterise. Like elementary particles, they can be fully described by just three parameters:

1) their mass

2) rotation speed and

3) electric charge

They contain no other information.

Evidence

This is the first image of Sagittarius A* (or Sgr A* for short), the supermassive black hole at the centre of our galaxy.

It’s the first direct visual evidence of the presence of this black hole. It was captured by the Event Horizon Telescope (EHT), an array which linked together eight existing radio observatories across the planet to form a single “Earth-sized” virtual telescope.

The telescope is named after the “event horizon”, the boundary of the black hole beyond which no light can escape.

We can clearly see a dark central region (called “shadow”) surrounded by a bright ring-like structure. The new view captures light bent by the powerful gravity of the black hole, which is four million times more massive than our Sun. The image of the Sgr A* black hole is an average of the different images the EHT Collaboration has extracted from its 2017 observations.

Enthusiasm

“We were stunned by how well the size of the ring agreed with predictions from Einstein’s Theory of General Relativity,” said EHT Project Scientist Geoffrey Bower from the Institute of Astronomy and Astrophysics, Academia Sinica, Taipei.

“These unprecedented observations have greatly improved our understanding of what happens at the very centre of our galaxy, and offer new insights on how these giant black holes interact with their surroundings.”