Gravitational Wave Observations

What are Quasars?


From UPSC perspective, the following things are important :

Prelims level : Quasars

Mains level : Black holes and gravitation waves

An international team of astronomers have discovered the most distant ‘radio-loud’ quasar with the help of the European Southern Observatory’s Very Large Telescope (ESO’s VLT).

Ever found this on YouTube? Take time to watch this amazing video. It will literally blow up your mind and curiosity!


TIMELAPSE OF THE FUTURE: A Journey to the End of Time (4K)


This video will make up your perceptions and conceptions of how a galaxy dies after the sun runs out of fuel and what a black hole actually is!

What are Quasars?

  • A quasar known as a quasi-stellar object is an extremely luminous active galactic nucleus (AGN), in which a supermassive black hole with mass ranging from millions to billions of times the mass of the Sun is surrounded by a gaseous accretion disk.
  • As gas in the disk falls towards the black hole, energy is released in the form of electromagnetic radiation, which can be observed across the electromagnetic spectrum.
  • The power radiated by quasars is enormous; the most powerful quasars have luminosities thousands of times greater than a galaxy such as the Milky Way.
  • Most active galaxies have a supermassive black hole at the centre which sucks in surrounding objects.
  • Quasars are formed by the energy emitted by materials spiralling around a black hole right before being sucked into it.

What makes this event special?

  • 90 per cent of quasars do not emit strong radio waves, making this newly-discovered one special.
  • It took 13 billion years for the quasar’s light to reach earth.
  • Named P172+18, the quasar emitted wavelengths had a redshift of 6.8.
  • Only three other ‘radio-loud’ sources with a redshift greater than six have been discovered so far and the most distant one had a redshift of 6.18.
  • The higher the redshift of the radio wavelength, the farther away is the source.

As an object moves away from us, the sound or light waves emitted by the object are stretched out, which makes them have a lower pitch and moves them towards the red end of the electromagnetic spectrum, where light has a longer wavelength. In the case of light waves, this is called redshift.

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Rajat Tyagi
Rajat Tyagi
1 year ago

Thanks for the suggestion. Truly mind-blowing video!!

aman lakhisarani
aman lakhisarani
1 year ago
Reply to  Rajat Tyagi

yeah it was