Narrow-Line Seyfert 1 (NLS1) Galaxy


  • Astronomers have discovered a new active galaxy identified as the farthest gamma-ray emitting galaxy that has so far been stumbled upon. This active galaxy called the Narrow-Line Seyfert 1 (NLS1) galaxy.

Key Details

  • Ever since 1929, when Edwin Hubble discovered that the Universe is expanding, it has been known that most other galaxies are moving away from us.
  • Light from these galaxies is shifted to longer (and this means redder) wavelengths – in other words, it is red-shifted.
  • Scientists have been trying to trace such red-shifted galaxies to understand the early Universe.
  • Powerful relativistic jets, or sources of particles in the Universe travelling nearly at speed to light, are usually produced by AGN powered by large black holes and hosted in a giant elliptical galaxy.

NLS1 Galaxy

  • Indian scientists have studied around 25,000 luminous Active galactic nuclei (AGN) from the Sloan Digital Sky Survey (SDSS).
  • They identified it as a gamma-ray emitting NLS1 galaxy, which is a rare entity in space.
  • It is about 31 billion light-years away, opens up avenues to explore more such gamma-ray emitting galaxies that wait to meet us.
  • NLS1s are a unique class of AGN that are powered by the black hole of low mass and hosted in a spiral galaxy.
  • As of today, gamma-ray emission has been detected in about a dozen NLS1 galaxies, which are a separate class of AGN identified four decades ago.
  • All of them are at redshifts lesser than one, and no method was present to date to find NLS1 at redshifts larger than one.
  • This discovery opens up a new way to find gamma-ray emitting NLS1 galaxies in the early Universe.

Back to Basics

Gamma Ray Astronomy

  • It is the study of astronomical objects and phenomena that emit gamma rays. Gamma-ray telescopes are designed to observe high-energy astrophysical systems.
  • As Earth’s atmosphere blocks most gamma rays, observations are generally conducted by high-altitude balloons or spacecraft.
  • Gamma-ray astronomy presents unique opportunities to explore exotic objects. By exploring the universe at these high energies, scientists can search for new physics, testing theories and performing experiments which are not possible in earth-bound laboratories.

Source: PIB

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