SARAS-3 RADIO TELESCOPE

SARAS-3 RADIO TELESCOPE

TOPIC: Science & Tech

Context- The RRI group made an updated version of SARAS, called SARAS-3 to detect radio wave signal from Cosmic Dawn.

Concept-

Background:

• In 2018 a team of researchers from Arizona State University (ASU) and MIT in the US detected a signal from stars emerging in the early universe using data from the EDGES radio telescope.
• ASU/MIT team had claimed the discovery of a radio wave signalling the birth of the First Stars.
• However Utilizing the indigenously invented and built SARAS 3 radio telescope, researchers from Raman Research Institute, an autonomous institute of the Department of Science & Technology, Govt. of India has refuted this claim.

SARAS-3 radio telescope:

• SARAS is a niche high-risk high-gain experimental effort of RRI initiated and led by Prof. Ravi Subrahmanyan, along with Prof. N. Udaya Shankar.
• SARAS is a correlation spectrometer designed for precision measurements of the cosmic radio background and faint features in the sky spectrum at long wavelengths.
• It was built to deploy in India a precision radio telescope to detect extremely faint radio wave signals from the depths of time, from our “Cosmic Dawn” when the first stars and galaxies formed in the early Universe.
• SARAS-3 is the first telescope worldwide to reach the required sensitivity and cross-verify the claim of the signal detection.
• Detecting a faint signal from such an early period of the Universe is extremely difficult.
• The celestial signal is exceptionally faint – buried in sky radio waves that come to us from the gas in our own Galaxy, the Milky Way, which are a million times brighter.
• Besides, this cosmic signal is in a radio wavelength band used by numerous terrestrial communications equipment and TV and FM radio stations, which makes detecting the extra-terrestrial signal extremely difficult.
• However, RRI scientists and engineers have risen to the challenge and designed and calibrated the SARAS radio telescope to discern signals from Cosmic Dawn.
• The telescope was first deployed in rural Timbaktu Collective in Anantapur district in Andhra Pradesh.
• The subsequent deployment took place in trans-Himalayan Ladakh and further RRI astronomers came up with the idea of floating the radio telescope on a raft on water, which had never been conceived of in the world.
• This helped provide a homogenous medium of high dielectric constant below the antenna improving sensitivity and reducing confusing radio waves emitted by the very ground beneath radio telescopes.
• In 2020, the radio telescope was deployed in lakes in Northern Karnataka, on Dandiganahalli Lake and Sharavati backwaters.
• After a rigorous statistical analysis SARAS 3 did not find any evidence of the signal claimed by the EDGES experiment.
• The presence of the signal is decisively rejected after a careful assessment of the measurement uncertainties.