P172+18 Quasar

In News

• 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).

About the Discovery

• It is named P172+18, the quasar emitted wavelengths which had a redshift of 6.8.
  • Gravitational redshift occurs as particles of light (photons) climb out of a gravitational well like a black hole and the light’s wavelength gets drawn out. This shifts the wavelength to the red part of the light spectrum – hence “redshift”.
  • It took 13 billion years for the quasar’s light to reach earth.
  • The higher the redshift of the radio wavelength, the farther away is the source.
• The glowing disc around a blackhole is 300 million times more massive than our Sun.
• It is also one of the fastest accreting quasars, which means it is accumulating objects from the galaxy at an enormous speed.
• Only three other ‘radio-loud’ sources with redshift greater than six have been discovered so far and the most distant one had a redshift of 6.18.
• The scientists think that the powerful radio jets shooting out of the quasar fuelled the appetite of the black hole.
  • The jets are thought to be capable of disturbing the gas around the black hole, increasing the rate at which gas falls in.
• Inference: The blackhole at its centre is consuming from its galaxy at a stunning rate.

Significance

• A detailed study of these ‘radio-loud’ super bright objects can help the astronomers to understand how the supermassive black holes in their core grew to be as big so rapidly since the Big Bang.
• The team believes that more such quasars that tell stories about the ancient universe will be found, perhaps even farther away from earth.

What are Quasars?

• Quasi Stellar radio sources, abbreviated QUASARS, are the most dynamic and far-off objects in a collective known as active galactic nuclei (AGN).
• Its spectrum consisted of wide emission lines, unlike stars, thus the name “quasi-stellar.”
• These radiant sources were formed approximately twelve billion years ago.
• Quasar formations take place by the collision of galaxies, i.e., the central black holes merge to form a supermassive black hole.
• Quasars are very luminous objects in faraway galaxies that emit jets at radio frequencies. They are only found in galaxies that have supermassive black holes which power these bright discs.
•  However, 90 percent of them do not emit strong radio waves, making this newly-discovered one special.
• Most active galaxies have a supermassive black hole at the centre which sucks in surrounding objects.

• Although quasars were originally discovered due to their radio emissions, only about 10% of quasars have substantial radio emissions.
  • These quasars are now called radio-loud quasars.
  • Quasars without strong radio emissions are called radio-quiet quasars

Source :DTH