SARAS 3 radio telescope refutes recent claim of the discovery of a radio wave signal from cosmic daw
- Indian researchers have conclusively refuted a recent claim of the discovery of a radio wave signal from cosmic dawn
- Cosmic dawn was time in the infancy of the Universe when the first stars and galaxies came into existence.
- 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.
- The ASU/MIT team had claimed discovery of a radio wave signalling the birth of the First Stars
- However confirmation from independent researchers was awaited to confirm this finding
- Researchers from Raman Research Institute, refuted this claim of ASU/MIT team by utilising the indigenously invented and built SARAS 3 radio telescope
SARAS 3 radio telescope
- It is a niche high-risk high-gain experimental effort of Raman Research Institute(RRI)
- It is the first telescope worldwide to reach the required sensitivity.
- It is the first attempt to design, build and deploy in India a precision radio telescope to detect extremely faint radio wave signals from the depths of time, from “Cosmic Dawn” when the first stars and galaxies formed in the early Universe.
SARAS: experiment and science
- The CMB Distortion Laboratory at RRI have developed state-of-the-art radio telescopes which are designed to detect faint cosmological signals, especially radiation emitted by hydrogen atoms at the 21-cm wavelength (1.4 GHz) arising from the depths of the cosmos.
- The signal from Cosmic Dawn is expected to arrive on Earth stretched in wavelength to metres and lowered in frequency by the expansion of the Universe to lie in the radio frequency band 50-200 MHz.
- This cosmic signal is in a radio wavelength band used by numerous terrestrial communications equipment and TV and FM radio stations
- It makes detecting the extra-terrestrial signal extremely difficult.
- The SARAS radio telescope was designed to discern signals from Cosmic Dawn.
- The telescope was deployed in isolated sites in India to gather celestial radio waves with minimum terrestrial man-made radio interference.
Deployment of the telescope over Water
- The Radio telescope was floated on raft of water to enhance telescope performance
- It had never been conceived of in the world.
- This helped to provide a homogenous medium of high dielectric constant below the antenna improving sensitivity
- It reduced the confusing radio waves emitted by the very ground beneath radio telescopes.
- The focused goal during this deployment was the cross-verification of the claimed detection of the 21-cm signal by the ASU/MIT EDGES experiment.
Findings of telescope
- 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.
- Therefore, the finding implies that the detection reported by EDGES was likely contamination of their measurement and not a signal from the depths of space and time.
- SARAS 3 was indeed the first experiment to reach the required sensitivity and cross-verify the claim of the signal detection.
Way Ahead for SARAS 3 radio telescope
- As the astronomers still do not know what the actual signal looks like.
- So the SARAS experiment is geared towards discovering the true nature of Cosmic Dawn after rejecting the ASU/MIT claim
- The SARAS 3 team at RRI is planning more observations on remote lakes in India.
- Such expeditions will allow the team to detect the 21-cm signal from the Cosmic Dawn and unravel this last remaining gap in the history of our Universe.
- This research of the Raman Research Institute restores confidence in understanding of the evolving Universe, re-establishing the prevailing cosmological model of the cosmos and moving forward to discover more things in this direction.