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Scientists discovered One of the Earliest Galaxies

Scientists discovered One of the Earliest Galaxies


Scientists of the Inter-University Centre for Astronomy and Astrophysics have discovered one of the earliest galaxies in extreme ultraviolet light.

  • AstroSat (multi-wavelength satellite) has detected extreme UV light from a galaxy called AUDFs01, 9.3 billion light-years away from Earth.


  • Scientists observed the galaxy, which is located in the Extreme Deep field, through AstroSat. In 2016 these observations lasted for more than 28 hours. But it took nearly two years since then to analyze the data to ascertain that the emission is indeed from the galaxy.
  • This clue helps to know how the dark ages of the Universe ended and there was light in the Universe.
    • Since UV radiation is absorbed by Earth’s atmosphere, it has to be observed from space.
  • Earlier, NASA’s Hubble Space Telescope, which is larger than the Ultra Violet Imaging Telescope on Astrosat, did not detect any UV emission from this galaxy because it is too faint.
  • “AstroSat was able to achieve this feat because the background noise in the Ultra Violet Imaging Telescope detector is much less than the ones on HST.

Dark ages of the Universe:

  • After the Big Bang, the Universe was a hot soup of particles (i.e., protons, neutrons, and electrons).
  • As the universe started to cool, the protons and neutrons began combining into ionized atoms of hydrogen (and eventually some helium).
  • These ionized atoms of hydrogen and helium attracted electrons and turn them into neutral atoms. 
  • Neutral atoms allowed light to travel freely for the first time since this light was no longer scattering off free electrons. The universe was no longer opaque. But there were no stars, and no galaxies and the Universe was dark.
  • After a few hundred million years after the Big Bang, the dark ages ended when the first stars and galaxies formed and the energy pouring out from them ionized the hydrogen and helium, splitting the atoms back again in protons and electrons.


  • It is India’s first dedicated multi-wavelength space observatory. 
  • The ASTROSAT enables the simultaneous multi-wavelength observations of various astronomical objects with a single satellite.
  •  It was launched on a PSLV-XL in 2015
  • ASTROSAT observes the universe in the optical, Ultraviolet, low, and high energy X-ray regions of the electromagnetic spectrum, whereas most other scientific satellites, are capable of observing a narrow range of wavelength band.


  • To understand high energy processes in binary star systems containing neutron stars and black holes
  • Estimate magnetic fields of neutron stars
  • Study star birth regions and high energy processes in star systems lying beyond our galaxy
  • Detect new briefly bright X-ray sources in the sky
  • Perform a limited deep field survey of the Universe in the Ultraviolet region

Payloads of ASTROSAT:

  • Five payloads of ASTROSAT are chosen to facilitate a deeper insight into the various astrophysical processes:
    • The Ultraviolet Imaging Telescope (UVIT): It is capable of observing the sky in the Visible, Near Ultraviolet and Far Ultraviolet regions of the electromagnetic spectrum
    • Large Area X-ray Proportional Counter (LAXPC): It is designed to study the variations in the emission of X-rays from sources like X-ray binaries, Active Galactic Nuclei, and other cosmic sources.
    • Soft X-ray Telescope (SXT): It is designed for studying how the X-ray spectrum of 0.3-8 keV range coming from distant celestial bodies varies with time.
    • Cadmium Zinc Telluride Imager (CZTI): It functioning in the X-ray region, extends the capability of the satellite to sense X-rays of high energy in 10-100 keV range.
    • Scanning Sky Monitor(SSM): It is intended to scan the sky for long term monitoring of bright X-ray sources in binary stars, and for the detection and location of sources that become bright in X-rays for a short duration of time.

Source: Indian Express