GIANT METREWAVE RADIO TELESCOPE - SCIENCE

Giant Metrewave Radio Telescope - SCIENCE

News: Indian astronomers use the Giant Metrewave Radio Telescope (GMRT) to discover 34 new giant radio sources (GRSs).

 

What’s in the news?

  • Discovery of Giant Radio Sources: A team of Indian radio astronomers has identified 34 new giant radio sources (GRSs). 
    • The findings have been published in the Astrophysical Journal Supplement Series (ApJS) of the American Astronomical Society.
  • Challenging Conventional Views: Two of the newly discovered GRSs, J0843+0513 and J1138+4540, challenge the conventional notion that GRSs grow only in low-density environments. 
    • Researchers said that factors other than environmental density play a significant role in the exceptionally large size of Giant Radio Galaxies (GRGs).
  • Telescope Used: The discovery was made using the Giant Metrewave Radio Telescope (GMRT), located near Khodad village, about 90 km north of Pune.
    • The GMRT is operated by the National Centre for Radio Astrophysics (NCRA) of the Tata Institute of Fundamental Research (TIFR).
    • This telescope surveyed the radio sky at a low frequency, making it ideal for detecting these faint, distant objects.
  • Survey Used: From 2010 to 2012, a survey was performed using the GMRT to map the radio sky at 150 MHz, known as the TIFR GMRT Sky Survey (TGSS) covering about 90% of the sky. 
    • The team of astronomers used TIFR GMRT Sky Survey (TGSS) for their research due to its low frequencies and the sensitivity of the GMRT. 
  • Advantages of Low-Frequency Radio Surveys
    • Suitability for Identification: Low-frequency radio surveys are more effective for identifying GRSs compared to higher-frequency surveys.
    • Brightness of Aged Plasma: Aged plasma in GRSs is brighter at low frequencies, making it easier to detect.

 

Historical Background

  • Past Discovery Rate: Only about 100 giant radio sources were known 20 years ago.
  • Reason for Limited Discovery: This number was a tiny fraction of the actual population due to observational limitations.
  • Advancements in Detection: The commissioning of new telescopes operating at low frequencies, such as GMRT (Giant Metrewave Radio Telescope) and LOFAR (Low-Frequency Array), has significantly increased the number of known giant radio sources to a few thousand.

 

Giant Radio Sources (GRS)

  • About: Giant Radio Sources (GRS) are among the largest structures in the universe.
    • They are powered by supermassive black holes at their centres, which are millions to billions of times heavier than the Sun.

These black holes emit powerful jets of hot plasma that create massive radio-emitting lobes, extending well beyond the visible parts of the galaxy.

 

  • Significance: 
    • Final Stage of Radio Galaxies: GRSs are believed to represent the final stage in the life of a radio galaxy due to their immense size.
    • Insights into Radio Galaxy Evolution: The size and structure of GRSs provide valuable insights into the evolution of radio galaxies.
      • The study of GRSs helps scientists understand the relationship between black hole activity and the evolution of radio galaxies.
    • Understanding Interstitial Space: GRSs offer insights into the interstitial space between the lobes of radio galaxies.
    • Cosmic Matter Distribution and Behavior: Research on giant radio galaxies aids in comprehending the distribution and behaviour of matter in the cosmos.
  • Challenges in Observing and Discovering Giant Radio Sources: 
    • Separation Issue: As radio sources grow in size, their ends become more widely separated.
    • Connection Difficulty: The increased separation makes it challenging to observationally connect the ends as part of the same source.

 

Source: https://indianexpress.com/article/cities/pune/indian-astronomers-discover-giant-radio-sources-9489547/