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SgrA Black hole in Milky Way Galaxy

Posted on May 13, 2022 by admin1  673

In News

  • Scientists from the Event Horizon Telescope facility revealed the first image of the black hole at the centre of the Milky Way galaxy.

About

  • Event Horizon Telescope (EHT), a collaboration of 300 researchers, reveals true colours of Sagittarius A* (SgrA*), the black hole.
  • The image confirms that the object is indeed a black hole and yields valuable clues about the workings of such giants which reside at the centre of most galaxies.

Important Findings

  • Reaffirms black hole in Milky way: The obtained image of SgrA* supports the veracity of the conception that the compact object at the centre of our galaxy is indeed a black hole.
  • Supports Theory of Relativity: The size of the ring confirms the predictions of Einstein’s general theory of relativity thereby strengthening the theory.
  • Second black hole imaging: SgrA* is only one-thousandth the size of M87*, a black hole in the Messier 87 galaxy but the ring of both the black holes looks strikingly similar.
  • Better heuristics: The collaboration will improve the capacity to have better imaging of other black holes with higher accuracy and better study of the associated magnetic fields.

Imaging SgrA* was much more difficult than M87*

  • Smaller size: SgrA* is only one-thousandth the size of M87*
  • Obscure line of sight: The line of sight is not very clear because of a lot of matter between the telescope and the blackhole.
  • Low gas swirling period: Being much smaller than M87*, the gas swirling around SgrA* takes just few minutes to complete an orbit around SgrA* compared to weeks to go around M87*. 
  • The blackhole does not have an image of its own, rather it’s the gasses swirling around which actually produce images.

Earlier snaps by EHT

  • The Event Horizon Telescope created history in 2019 by releasing the first ever image of a black hole M87*.
  • The M87* black hole is situated at the centre of a galaxy Messier 87, which is a supergiant elliptic galaxy.

Event Horizon Telescope

  • About: The Event Horizon Telescope is a global network of synchronized radio observatories that work in unison to observe radio sources associated with black holes with angular resolution comparable to their event horizons.
  • Objective: The EHT has been designed for imaging of black holes. It offers scientists to research new frontiers of the Universe.
  • Technology deployed: The EHT observations use a technique called very-long-baseline interferometry (VLBI) to capture the images of black holes.
  • Unison of 8 telescopes: The EHT comprising 8 telescopes around the globe, forms an Earth-sized virtual telescope with unprecedented sensitivity and resolution. Components of EHT across the globe:

 

Black Holes

  • About: 
    • A black hole is a place in space where gravity pulls so much that even light cannot escape. The gravity is so strong because matter has been squeezed into a tiny space. This can happen when a star is dying.
  • Visibility: 
    • Because no light can get out, they are invisible. Space telescopes with special tools can help find black holes. The gasses swirling around actually help in getting their images.
  • How Big Are Black Holes?
    • Black holes can be big or small. Scientists think the smallest black holes are as small as just one atom. These black holes are very tiny but have the mass of a large mountain. 
    • Another kind of black hole is called “stellar.” Its mass can be up to 20 times more than the mass of the sun. 
    • The largest black holes are called ‘supermassive’ and they have masses that are more than 1 million suns together. 
    • SgrA*
      • The supermassive black hole at the center of the Milky Way galaxy is called Sagittarius A.
      • It has a mass equal to about 4 million suns and would fit inside a very large ball that could hold a few million Earths.
  •  How Do Black Holes Form?
    • Scientists think the smallest black holes formed when the universe began.
    • Stellar black holes are made when the center of a very big star falls in upon itself or collapses. When this happens, it causes a supernova. A supernova is an exploding star that blasts part of the star into space.
    • Scientists think supermassive black holes were made at the same time as the galaxy they are in.

Source: TH

 
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